Development and
Implementation of Fisheries Bycatch Monitoring Programs In
The Gulf Of Mexico
Acknowledgment
Many
individuals contributed to the development of this report.
We would like to thank all Gulf of Mexico Program partners
who gave of their time, energy and expertise in creating
this document. Special thanks are also due to the numerous
state and federal agency personnel who provided the authors
with many hard-to-find references. This document has been
funded by the United States Environmental Protection Agency
under Cooperative Agreement Number MX-994717-95-0 awarded to
the Mississippi Agricultural and Forestry Experiment Station
of Mississippi State University. The contents of this
document do not necessarily represent the views and policies
of the Environmental Protection Agency, nor does the mention
of trade names or commercial products constitute an
endorsement or recommendation.
David
D. Burrage
Mississippi State University Coastal Research &
Extension Center
Sea Grant Advisory Service
2710 Beach Boulevard, Suite 1-E
Biloxi, MS 39531
Steven
G. Branstetter
Gulf & South Atlantic Fisheries Development
Foundation, Inc.
Lincoln Center, Suite 997
5401 West Kennedy Boulevard
Tampa, FL 33609
Gary
Graham
Texas Agricultural Extension Service
Sea Grant College Program
P.O. Box 1675
Galveston, TX 77553-1675
Richard
K. Wallace
Auburn University Marine Extension & Research
Center
Sea Grant Extension
4170 Commanders Drive
Mobile, AL 36615
TABLE OF
CONTENTS
THE
ROLE OF BYCATCH IN FISHERIES
CONSERVATION AND MANAGEMENT
Fishery
resources are harvested from Gulf of Mexico waters using a
variety of gears and methods. With few exceptions, most of
the fisheries have an element of bycatch associated with
them. For purposes of this report, "bycatch" includes
discarded fish, shellfish, or other organisms which are
taken as non-target incidental catch in fisheries. Bycatch
includes those fish and shellfish that have no market value,
are damaged during harvest, or cannot be legally retained,
landed, or sold. Other organisms such as marine mammals,
birds, and turtles are accidentally caught and discarded in
some fisheries. The fishing event may cause either immediate
mortality or the potential for future mortality as a result
of gear interactions or handling.
Fisheries
in the Gulf of Mexico are prosecuted under a wide range of
management regimes. In waters beyond state jurisdiction,
many fisheries are managed under federal regulations
promulgated by the National Marine Fisheries Service (NMFS)
and the Gulf of Mexico Fishery Management Council (Council).
Fishery resources taken primarily from state waters are
managed by the respective Gulf states, and some species are
managed through interstate compacts initiated and developed
by the Gulf States Marine Fisheries Commission (Commission).
Fishery management, in the Gulf of Mexico and worldwide, has
intensified and undergone many changes. Limited entry, ITQ
(individual transferable quotas which privatize harvesting
rights), trip limits (frequency and landing limits), gear
restrictions, area closures, and seasons further restrict
the fishing industry. Often more than one management method
is employed simultaneously. All of these management options
strongly influence bycatch and discard rates either by
changing fishermen's behavior or altering the type of
fishing technology used.
The
discard of bycatch or lower-valued fish (high-grading) is
among the most difficult fishery management challenges,
making attainment of conservation and economic goals of
fishery managers, the fishing industry, and the public
problematic (Dewees and Ueber, 1990). Probably more common
is bycatch from non-selective harvesting gear. These
discards contribute to the fishing-related mortality of many
species and are a factor in management decisions such as
setting catch quotas and fishing seasons. Fishery bycatch
also plays a larger role in the overall balance of the Gulf
ecosystem when viewed in light of the fate of discards,
predator-prey relationships, and environmental
quality.
Bycatch
in the Gulf of Mexico is an issue of great concern when
viewed in light of the many fisheries which are conducted in
the region and the level of effort being expended to harvest
fishery resources. Most bycatch research has focused on the
commercial shrimp fishery. According to a recent FAO report
(Alverson et al., 1994), this fishery ranks fifth in the
world in bycatch generated (discard weight per landed target
catch weight). Many other fisheries and fishing gears within
the Gulf also impact non-target species. These include
pelagic and bottom longlines, commercial hook and line,
purse seines, trap fisheries, gill and trammel nets,
recreational hook and line, finfish trawls, and recreational
shrimp trawls. Bycatch in these fisheries is generated by
incidental catch of non-target species and release of
regulated species which are under- or over-sized or out of
season. Given the large area covered, the multitude of
fisheries, and an increasing population that heavily uses
marine resources, addressing the bycatch issue is a timely
endeavor.
OVERVIEW
OF GULF OF MEXICO FISHERIES
The
fishery resources in the Gulf of Mexico support an extensive
commercial and recreational fishery. Due to increased
demands for fishery products in the marketplace and an
increase in individual leisure time and discretionary
income, more pressure is being brought to bear on the
fishery resources of the Gulf. It is important to understand
the status of the fishery resources and the demands being
placed on them. The total United States commercial harvest
in 1995 was 9.9 billion pounds or 4.5 million metric tons
with an ex-vessel value (price paid to the fishermen) of
$3.8 billion. The five Gulf states produced 15 percent (1.4
billion pounds) of this volume and accounted for 19 percent
($725 million) of the value of these landings (NMFS, 1996).
Included in these landings are shrimp, the most valuable
fishery in the nation; and menhaden, the second largest
fishery by volume in the nation. In 1995, marine
recreational fishermen in Florida, Alabama, Mississippi, and
Louisiana participated in 17 million fishing trips and
landed approximately 136 million fish. Thirty percent of all
marine recreational angling trips in the nation occurred in
the Gulf and these anglers landed 44 percent of all fish
reported in 1995 (NMFS, 1996).
According
to the latest estimates, there are 33,696 commercial fishing
vessels registered or documented in the five Gulf states
(NMFS, 1996). Approximately 25,000 of these are classified
as "boats" (under five net tons) which are typically used in
inshore fisheries such as oyster tonging, gill netting, and
crabbing. Over 8,000 units of the commercial fishing fleet
are classified as "vessels" (over five net tons). These are
the offshore shrimp trawlers, longline and bandit-rigged
reef fish vessels, pelagic longliners, oyster dredgers,
purse seiners, and finfish draggers. Many of the larger
vessels are typically rigged to participate in more than one
fishery.
The
amount of effort expended in Gulf fisheries can be
approximated by examining license sales in each of the Gulf
states. The National Marine Fisheries Service also issues
permits for several fisheries which are conducted primarily
in federal waters. The number of licenses sold in each
fishery by state is not a true indicator of the total number
of fishermen harvesting Gulf resources because some
fishermen purchase several licenses in their own or other
states for the same fishery. However, if one distinguishes
between resident and nonresident sales, a better
approximation can be obtained. Additionally, states vary in
the way licenses are issued. For example, some states
license vessels, others license individuals, and others do
both. Some states have exemptions for certain classes of
people regarding license requirements in some fisheries. The
following tables are compiled from information obtained from
the Gulf States Marine Fisheries Commission (1996) and the
National Marine Fisheries Service (1996):
|
FLORIDA
|
|
Type
of License
|
Number
Sold FY95
|
|
Resident
Annual Salt Water Sport Fishing
|
542,378
|
|
Resident
10-Day Salt Water Sport Fishing
|
56
|
|
Nonresident
Annual Salt Water Sport Fishing
|
75,395
|
|
Nonresident
7-Day Salt Water Sport Fishing
|
51,578
|
|
Nonresident
3-Day Salt Water Sport Fishing
|
207,571
|
|
Blue
Crab Permit
|
6,082
|
|
Stone
Crab Permit
|
7,258
|
|
Crawfish
Permit
|
2,463
|
|
Spiny
Lobster Trap Certificate -- Each Trap
|
63,470
|
|
Shellfish
Relaying Permit
|
20
|
|
Shellfish
Leases
|
386
|
|
Resident
Apalachicola Bay Oyster Harvesting
|
748
|
|
Nonresident
Apalachicola Bay Oyster Harvesting
|
2
|
|
Noncommercial
Lobster Permits
|
520
|
|
Noncommercial
Shrimp Permits
|
403
|
|
Resident
Indian River Clam Permit
|
900
|
|
Nonresident
Indian River Clam Permit
|
74
|
|
Dead
Shrimp Production License - -St. Johns River
Only
|
74
|
|
Bait
Shrimp -- Statewide
|
111
|
|
Live
Shrimp Production License
|
73
|
|
Noncommercial
Shrimp Trawling License -- St. Johns River
Only
|
17
|
|
Purse
Seine*
|
208
|
|
Manatee
County Gill Net*
|
219
|
|
Pinellas
County Gill Net*
|
55
|
|
Nassau
County Gill Net*
|
0
|
|
Hillsborough
County Gill Net*
|
45
|
|
Sarasota
County Gill Net*
|
82
|
|
St.
Johns County Beach Seine
|
7
|
|
License
to Take Sardine-like Fish from Pinellas County
Waters
|
5
|
|
Pleasure
Vessel Registrations
|
713,413
|
|
Commercial
Vessel Registrations
|
34,188
|
|
Nonresident
or Alien Commercial Vessel Fees
|
674
|
|
Resident
Saltwater Products
|
18,933
|
|
Nonresident
Saltwater Products
|
728
|
|
Alien
Saltwater Products
|
136
|
|
Restricted
Species Endorsement
|
9,503
|
|
*These
types of license will probably decline drastically
due to Florida's recent net ban which was
instituted on July 1, 1995.
|
|
MISSISSIPPI
|
|
Type
of License
|
Number
Sold FY95
|
|
Resident
Salt Water Sport Fishing
|
48,444
|
|
Nonresident
Salt Water Sport Fishing
|
6,645
|
|
Resident
Gill and Trammel Net
|
220
|
|
Nonresident
Gill and Trammel Net
|
4
|
|
Resident
Recreational Shrimp
|
503
|
|
Nonresident
Recreational Shrimp
|
1
|
|
Resident
Shrimp Under 30'
|
347
|
|
Nonresident
Shrimp Under 30'
|
3
|
|
Resident
Shrimp 30' to 45'
|
389
|
|
Nonresident
Shrimp 30' to 45'
|
39
|
|
Resident
Shrimp Over 45'
|
449
|
|
Nonresident
Shrimp Over 45'
|
65
|
|
Resident
Commercial Crab
|
148
|
|
Nonresident
Commercial Crab
|
18
|
|
Recreational
Crab (Resident Only)
|
3
|
|
Charter/Party
Boat (Resident Only)
|
84
|
|
Commercial
Hook and Line
|
86
|
|
Recreational
Oyster (Resident Only)
|
105
|
|
Resident
Oyster Tonging
|
46
|
|
Nonresident
Oyster Tonging
|
25
|
|
Resident
Oyster Dredging
|
119
|
|
Nonresident
Oyster Dredging
|
15
|
|
Live
Bait Boat
|
37
|
|
ALABAMA
|
|
Type
of License
|
Number
Sold FY95
|
|
Resident
Annual Salt Water Rod and Reel
|
39,245
|
|
Nonresident
Annual Salt Water Rod and Reel
|
3,769
|
|
Resident
Commercial Oyster Catcher
|
707
|
|
Nonresident
Commercial Oyster Catcher
|
5
|
|
Shrimp
Under 30'
|
757
|
|
Shrimp
30' to 45'
|
222
|
|
Shrimp
Over 45'
|
199
|
|
Nonresident
Commercial Shrimp
|
242
|
|
Resident
Recreational Shrimp Boat
|
1,727
|
|
Nonresident
Recreational Shrimp Boat
|
90
|
|
Resident
Commercial Crab Fisherman
|
150
|
|
Nonresident
Commercial Crab Fisherman
|
3
|
|
Resident
Commercial Net License (1,200' or Less)
|
362
|
|
Nonresident
Commercial Net License (1,200' or Less)
|
30
|
|
Resident
Commercial Net License (1,201' to
2,400')
|
204
|
|
Nonresident
Commercial Net License (1,201' to
2,400')
|
42
|
|
Resident
Purse Seine
|
2
|
|
Nonresident
Purse Seine
|
8
|
|
Resident
Recreational Net (Not to Exceed 300')
|
384
|
|
Nonresident
Recreational Net (Not to Exceed 300')
|
17
|
|
Resident
Commercial Hook and Line
|
60
|
|
Nonresident
Commercial Hook and Line
|
0
|
|
Resident
Charter Boat -- 6 Passenger
|
70
|
|
Nonresident
Charter Boat -- 6 Passenger
|
8
|
|
Resident
Charter Boat -- 25 Passenger
|
14
|
|
Nonresident
Charter Boat -- 25 Passenger
|
0
|
|
Resident
Charter Boat -- Over 25 Passenger
|
1
|
|
Nonresident
Charter Boat -- Over 25 Passenger
|
2
|
|
LOUISIANA
|
|
Type
of License
|
Number
Sold FY95
|
|
Resident
Oyster Tong -- Per Tong
|
181
|
|
Resident
Oyster Dredge -- Per Dredge
|
1,084
|
|
Nonresident
Oyster Dredge -- Per Dredge
|
45
|
|
Resident
Commercial Fisherman
|
15,062
|
|
Resident
Hoop Net -- Any Legal Number
|
1,753
|
|
Resident
Fish Seine -- Any Legal Number
|
162
|
|
Resident
Trammel Net -- Any Legal Number
|
467
|
|
Resident
Freshwater Gill Net -- Any Legal
Number*
|
1,000
|
|
Nonresident
Hoop Net -- Any Legal Number
|
34
|
|
Nonresident
Trammel Net -- Any Legal Number*
|
17
|
|
Resident
Vessel License
|
14,323
|
|
Nonresident
Vessel License
|
1,581
|
|
Resident
Purse/Menhaden Seine -- Per Seine
|
57
|
|
Resident
Shrimp Trawl -- Per Trawl
|
10,095
|
|
Nonresident
Shrimp Trawl -- Per Trawl
|
3,553
|
|
Resident
Oyster Harvester
|
940
|
|
Nonresident
Oyster Harvester
|
28
|
|
Nonresident
Commercial Fisherman
|
1,625
|
|
Nonresident
Fish Seine -- Any Legal Number
|
1
|
|
Resident
Butterfly Net -- Per Net
|
3,050
|
|
Nonresident
Butterfly Net -- Per Net
|
37
|
|
Resident
Slat Trap -- Any Legal Number
|
218
|
|
Nonresident
Slat Trap -- Any Legal Number
|
0
|
|
Nonresident
Purse/Menhaden Seine -- Per Seine
|
1
|
|
Resident
Crab Trap -- Any Legal Number
|
3,423
|
|
Nonresident
Crab Trap -- Any Legal Number
|
65
|
|
Resident
Crab Trap Attached to Trotline
|
321
|
|
Resident
Eel Pot License
|
8
|
|
Resident
Minnow Trap License
|
136
|
|
Resident
Mullet Permit
|
582
|
|
Nonresident
Mullet Permit
|
79
|
|
Resident
Spear Gun -- Per Gun
|
29
|
|
Resident
Set Line License
|
1,185
|
|
Nonresident
Set Line License
|
133
|
|
Resident
Dip/Cast Net License
|
383
|
|
Nonresident
Dip/Cast Net -- Per Net
|
1
|
|
Resident
Flounder Gig License
|
25
|
|
Nonresident
Flounder Gig -- Per Gig
|
0
|
|
Resident
Can, Bucket, Pipe, Drum, Tire
|
66
|
|
Nonresident
Can, Bucket, Pipe, Drum, Tire
|
0
|
|
Resident
Skimmer Net
|
5,447
|
|
Nonresident
Skimmer Net
|
68
|
|
Resident
Saltwater Gill Net*
|
781
|
|
Nonresident
Saltwater Gill Net*
|
73
|
|
Resident
Mullet Strike Net*
|
755
|
|
Nonresident
Mullet Strike Net*
|
80
|
|
Resident
Pompano Strike Net*
|
34
|
|
Resident
Saltwater Rod and Reel
|
3
|
|
Resident
Spotted Seatrout Permit
|
73
|
|
Resident
Saltwater Gill Net for EEZ*
|
2
|
|
Nonresident
Saltwater Gill Net for EEZ*
|
1
|
|
Out
of State Oyster Landing Permit
|
13
|
|
Resident
Soft Shell Crab Shedder
|
36
|
|
Resident
Pompano Permit
|
8
|
|
Resident
Restricted Species Permit
|
46
|
|
Resident
Recreational Saltwater Fishing Season
|
280,360
|
|
Nonresident
Recreational Saltwater Fishing Season
|
6,510
|
|
Nonresident
Recreational Saltwater Trip -- 7 Days
|
1,269
|
|
Nonresident
Recreational Fresh/Saltwater Trip -- 2
Days
|
27,618
|
|
Resident
Recreational Hoop Net -- No More Than 5
Nets
|
4,288
|
|
Nonresident
Recreational Hoop Net -- No More Than 5
Nets
|
87
|
|
Resident
Recreational Slat Traps -- No More Than 5
Traps
|
746
|
|
Nonresident
Recreational Slat Traps -- No More Than 5
Traps
|
25
|
|
Resident
Recreational Crab Traps -- No More Than 10
Traps
|
3,116
|
|
Nonresident
Recreational Crab Traps -- No More Than 10
Traps
|
15
|
|
Resident
Recreational Shrimp Trawl -- Per 16'
Trawl
|
4,389
|
|
Nonresident
Recreational Shrimp Trawl -- Per 16'
Trawl
|
44
|
|
Resident
Recreational Oyster Tong -- Per Tong
|
63
|
|
Nonresident
Recreational Oyster Tong -- Per Tong
|
1
|
|
Resident
Recreational Crab Trap -- Per Trap on
Trotline
|
1,549
|
|
Nonresident
Recreational Crab Trap -- Per Trap on
Trotline
|
10
|
|
*These
types of license will probably decline drastically
due to Louisiana's recent net ban which will be
phased in by 1997.
|
|
|
TEXAS
|
|
Type
of License
|
Number
Sold FY95
|
|
Resident
Recreational Fishing
|
1,043,764
|
|
Lifetime
Resident Recreational Fishing
|
14
|
|
Temporary
Resident Recreational Fishing -- 14 Day
|
77,784
|
|
Saltwater
Sportfishing Stamp
|
624,218
|
|
Special
Resident Fishing
|
7,121
|
|
Nonresident
Recreational Fishing
|
47,109
|
|
Temporary
Nonresident Recreational Fishing -- 5
Day
|
63,236
|
|
Commercial
Crab Trap Tag
|
79,723
|
|
Saltwater
Trotline Tag
|
10,395
|
|
Resident
Commercial Oyster Fisherman
|
5
|
|
Nonresident
Commercial Oyster Fisherman
|
0
|
|
Resident
Commercial Oyster Boat Captain
|
413
|
|
Nonresident
Commercial Oyster Boat Captain
|
18
|
|
Resident
Commercial Oyster Boat
|
343
|
|
Nonresident
Commercial Oyster Boat
|
12
|
|
Resident
Sport Oyster Boat
|
78
|
|
Nonresident
Sport Oyster Boat
|
1
|
|
Resident
Commercial Fishing Boat (Fresh and
Saltwater)
|
1,334
|
|
Nonresident
Commercial Fishing Boat (Fresh and
Saltwater)
|
29
|
|
Resident
Commercial Mussel and Clam Fisherman
|
108
|
|
Nonresident
Commercial Mussel and Clam Fisherman
|
7
|
|
Commercial
Fishing Boat (Menhaden Only)
|
15
|
|
Resident
Commercial Gulf Shrimp Boat
|
896
|
|
Nonresident
Commercial Gulf Shrimp Boat
|
441
|
|
Resident
Commercial Bay Shrimp Boat
|
1,529
|
|
Nonresident
Commercial Bay Shrimp Boat
|
0
|
|
Resident
Commercial Bait Shrimp Boat
|
1,614
|
|
Nonresident
Commercial Bait Shrimp Boat
|
0
|
|
Shrimp
House Operator's Individual Bait Shrimp Trawl
Tag
|
974
|
|
Resident
General Commercial Fisherman's
|
4,175
|
|
Nonresident
General Commercial Fisherman's
|
45
|
|
Resident
Commercial Finfish Fisherman's
|
1,380
|
|
Nonresident
Commercial Finfish Fisherman's
|
11
|
|
FEDERAL
|
|
Type
of Permit/Endorsement
|
Number
Issued (Most Recent Fishing Year)
|
|
Gulf
and South Atlantic Shark
|
1,841
|
|
Swordfish
|
984
|
|
Coastal
Pelagics (Charter Boats Only)
|
1,455
|
|
Commercial
Mackerel (Includes Gill Net Endorsement)
|
2,839
|
|
Commercial
Mackerel Gill Net Endorsement
|
115
|
|
Reef
Fish (Charter Boats Only)
|
515
|
|
Commercial
Reef Fish (Includes Bandit, Longline and
Trap)
|
1,451
|
|
Commercial
Reef Fish Trap
|
95
|
|
Commercial
Reef Fish Bandit
|
939
|
|
Commercial
Reef Fish Bottom Longline
|
436
|
|
Red
Snapper 2,000 Pound Endorsement
|
131
|
|
Commercial
Spiny Lobster
|
294
|
|
Spiny
Lobster Tailing Permit
|
377
|
OBJECTIVES
AND METHODOLOGY
The
general goals of the Gulf of Mexico Program regarding
fisheries bycatch are to 1) conserve and restore species
diversity and health of aquatic resources while allowing
sustainable development, 2) assess and monitor the effects
of fishing mortality on the health and abundance of living
aquatic resources in the Gulf of Mexico, 3) enhance the
sustainability of Gulf commercial and recreational
fisheries, and 4) identify and assess existing commercial
and recreational bycatch data to determine research needs.
The specific objectives of this project were as
follows:
- Conduct
a Gulfwide survey of agencies and organizations to
determine existing and on-going data and develop a data
catalog;
- Compile
and analyze these data, identify data gaps, and develop a
summary document for peer review and publication;
and
- Assist
the Gulf of Mexico Program with information and
technology transfer activities addressing fishery bycatch
in the Gulf of Mexico by disseminating information
developed under this project to a wide variety of user
groups, fishery managers, and the general
public.
The
methodology used in preparation of this report encompasses
more than the original scope of work specified by the Gulf
of Mexico Program. The authors made a conscious decision to
expand the search for relevant information beyond "a
Gulfwide survey of agencies and organizations" in order to
include work done outside of the region involving species
which are also indigenous to the Gulf of Mexico. Similarly,
work done in other areas with the same fishing gear types
used in the Gulf but targeting different species was
sometimes included in the analyses so that a variety of
research techniques and protocols could be compared and
evaluated. It is hoped that experience gleaned from this
wider examination of bycatch research will be useful in
shaping future efforts in the Gulf of Mexico region.
Cooperators in the project conducted a survey of agencies
and organizations to identify existing data. Contact points
were state and federal fishery management agencies, private
sector fishery organizations, academic researchers,
environmental entities, the Sea Grant advisory network, the
Gulf States Marine Fisheries Commission, and public/private
organizations such as the National Fisheries Institute and
fisheries development foundations. Data were compiled using
computer and literature searches as well as individual
personal contacts throughout the Gulf region. Much of the
documentation associated with this effort is in the form of
grant final reports, or reports to agencies, and some of it
is preliminary. More detailed and conclusive peer-reviewed
literature is likely forthcoming. The project collaborators
divided their efforts based on their respective knowledge of
the fisheries, fishing gears, and fishing techniques used to
harvest living marine resources from the Gulf of Mexico
region. The findings in this report are presented according
to a classification based on individual fisheries and major
gear types used. Wherever practical, citations include
mailing addresses to facilitate document acquisition by
interested readers.
THE
COMMERCIAL SHRIMP FISHERY
Shrimp
trawling has long been identified as a non-selective fishing
activity, with numerous species being vulnerable to the
nets. Bycatch in this fishery usually exceeds the catch of
shrimp. Since 1990, a comprehensive multi-organizational
effort, funded through federal, state and private sources,
has addressed shrimp trawl bycatch. Much of the
documentation of this effort is in the form of grant final
reports, or reports to agencies, and some of it is
preliminary. To date, the program has generated information
on nearly 6,000 commercial shrimp trawl tows in the
southeastern U.S., with a focus on the Gulf of Mexico. In
addition, several fishery-independent surveys have been
conducted. All totaled, there is a substantial database that
can be reviewed for characterization of the catch of the
commercial shrimp fishery, and more importantly, much
research has now been completed on options to reduce
bycatch. Reduction of finfish bycatch, especially for
certain heavily fished species such as red snapper, is
expected to help rebuild the stock. In the past few years,
the shrimp industry has modified its gear configurations and
operational techniques; these changes, though not
specifically designed to reduce finfish bycatch, achieved
that goal as well. For example, the addition of turtle
excluder devices (TEDs) in the fishery also reduced the
catch of finfish. Several bycatch reductions devices (BRDs)
have been tested in the Gulf of Mexico, and some designs
have shown good results at substantially reducing finfish
while losing only minimal amounts of shrimp.
Shrimp
Trawl Bycatch Characterization Studies:
- Adkins,
G. 1993. A comprehensive assessment of bycatch in the
Louisiana shrimp fishery. Technical Bulletin No. 42,
Louisiana Depart. Wildl. & Fisheries, Marine
Fisheries Div., Bourg, Louisiana 70343. Also
available as a MARFIN Final Report (Award
NA89WC-H-MF006), for the period 1 January 1989 through 31
December 1989.
- The
study compared the catch rates of offshore and inshore
trawlers and wingnet efforts during 108 commercial tows.
Brown and white shrimp comprised 60 percent of the catch
by number. By weight the average fish/shrimp ratio was
3.2:1 with inshore trawl bycatch higher (3.0 vs. 2.2:1)
than offshore trawling; wingnet bycatch was 4.7:1.
Although the wingnet catches were higher, the shorter tow
times and the handling procedures meant more was released
alive than from otter trawling. The study reviews much of
the bycatch literature available at the time, and notes
the possibilities of reducing bycatch through various
methods such as area/time closures, and use of excluder
devices.
- Baltz,
D. M. 1993. Patterns in the distribution and abundance of
fishes and macroinvertebrates in a Louisiana marsh:
shrimp bycatch in the inshore, fishery-independent trawl
samples. MARFIN Final Report (Award NA17FF0263-01) by
Louisiana State University, Coastal Fisheries Institute,
Baton Rouge, Louisiana 70803
- Using
a 20-year fishery-independent trawl survey of three
stations in coastal Louisiana, 141 taxa were identified
from over 2,000 tows. Of these taxa, 90 were considered
rare, with less than 100 individuals being documented
during the entire period; thus only about 50 species
occurred with some regularity. Of the 141 taxa, fish
comprised 110 species. Two species, the bay anchovy and
the Atlantic croaker, comprised 72 percent of the catch
by number. The study indicated a stable community
structure even with the highly fluctuating environmental
conditions that occurred on an annual or longer basis.
One disappointing point in this study is a lack of CPUE
data by year to indicate trends in relative abundance
over such a long time span. This analysis would have
suggested the long-term effects of trawling on bycatch
species found in inshore Louisiana waters (see Perret
et al. 1995; this section for that
information).
- Boylan,
J.M., R.P. Webster, H.R. Beatty, and E.L. Wenner. 1990.
Results of trawling efforts in the coastal habitat of the
South Atlantic Bight. SEAMAP--SA Final Report, FY-1990.
Marine Resources Research Div., South Carolina Wildl.
& Mar. Resources, Dept., P.O. Box 12559, Charleston,
SC 29412.
- This
study, looking at the South Atlantic Bight, stratified
analyses in an inner and outer area by depth. Diversity
and abundance was higher in the inner areas. The dominant
species overall was spot, occurring in 71 percent of the
samples. Atlantic croaker ranked second in frequency of
occurrence. The report focused analyses on the mackerels.
Spanish mackerel densities were estimated at 1.5
individuals per hectare and included fish from 3-51 cm
(mean = 20 cm); length frequencies indicated
young-of-the-year and early age-I fish in the catch. King
mackerel were estimated at one individual per hectare,
and ranged from 4-44 cm (mean = 18 cm), and length
frequencies indicated the presence of young-of-the-year
and a strong representation of age-I
individuals.
- Chittenden,
M.E. Jr., and J.D. McEachran. 1976. Composition, ecology,
and dynamics of demersal fish communities on the
northwestern Gulf of Mexico continental shelf, with a
similar synopsis for the entire Gulf. A Final Report to
Texas Sea Grant (TAMU-SG-76-208), Texas A&M
University, College Station, TX 77843.
- Collections
aboard commercial shrimp trawlers during normal working
conditions on 4 seasonal trips monitored 21 tows on white
shrimp grounds and 39 tows on brown shrimp grounds. 103
species were taken in the 18 kg/tow samples; an
additional 58 species were found in the culled catch of
the net. The discard to shrimp volume ratio was 11.35:1.
The document notes that the authors assumed invertebrates
made up 10-20 percent of the discard, thus the fish to
shrimp ratio was estimated at 10:1. The document does
note that the discard catch in the white shrimp grounds
may have been biased due to some large discard catches in
June.
- Coleman,
F.C., C.C. Koenig, and W.F. Herinkind. 1992. Annual
report: survey of Florida inshore shrimp trawling
by-catch and preliminary test of by-catch reduction
devices.(Copy received from Gulf of Mexico Fishery
Management Council who received it from the Florida
Marine Fisheries Commission. This study continued for at
least 2 more years; more recent results are probably
available from the authors at: Dept. Biological Sciences,
Florida St. Univ., Tallahassee, FL
32306).
- This
document presents the results of the first year's
analysis of an ongoing project. It provides a table of
the species composition of the catch in 10 different
Florida sites, and preliminary results of bycatch
reduction devices testing. The tabular material on
species composition is not ranked by abundance, although
the text does list the most abundant species. Given the
preliminary nature of this report, and its limited sample
sizes, few conclusions can be drawn; species composition
and abundance changed dramatically between seasonal
sampling trips, and differed substantially among
sites.
- Fuls,
B. 1995. Assessment of composition and magnitude of
bycatch associated with the commercial shrimp trawling
industry in central lower Texas coastal bays during
spring and fall Texas commercial bay-shrimp open seasons.
Saltonstall-Kennedy Program Final Report (Award
NA37FD0083) by Texas Parks and Wildl. Dept., Austin,
TX.
- Monitoring
three bays in lower Texas - Aransas Bay, Corpus Christi
Bay, and lower Laguna Madre - this study reported that
bycatch was higher in the spring than in the fall.
Bycatch to shrimp ratios were 4:1 to 6.8:1 depending upon
season and area. Finfish to shrimp ratios were 1:1 to
5.1:1, again varying by season and area. Bycatch ratios
were highest in Corpus Christi Bay and lowest in Laguna
Madre. The report also noted that the quantity and
composition of the bycatch in this fishery-independent
survey was very different from concurrent
fishery-dependent surveys.
Bait
shrimp bycatch surveys (9.8 m trawl) in Lower Laguna
Madre during the spring of 1993 showed that four species
(lesser blue crab, Callinectes similis; Atlantic
croaker, Micropogonias undulatus; spot,
Leiostomus xanthurus; and sand seatrout,
Cynoscion arenarius) comprised 62 percent and 43
percent of the mean CPUE in number and weight,
respectively. The overall mean CPUE for bycatch was 2,966
individuals/h/net in number and 54.643 kg/h/net in
weight. In the fall, five species (sand seatrout,
Cynoscion arenarius; lesser blue crab,
Callinectes similis; spotfin mojara,
Eucinostomus argenteus; hardhead catfish, Arius
felis; and Atlantic cutlassfish, Trichiurus
lepturus) comprised 65 percent and 53 percent of the
mean CPUE in number and weight, respectively. The overall
mean CPUE for bycatch organisms was 1,597
individuals/h/net in number and 27.775 kg/h/net in
weight.
- Griffin,
W.L., and A.K. Shah. 1995. Estimation of standardized
effort in the heterogeneous Gulf of Mexico shrimp fleet.
MARFIN final report (Award #NA37FF0053).
- Because
of concerns about shrimp effort estimates performed by
NMFS, this study was conducted to examine alternative
estimation techniques. Compared to the current NMFS
practice of expanding effort using simple average CPUEs
and extrapolating these data for empty cells, the models
used in this analysis correct for potential biases
associated with blank cells and non-proportional
reporting between interviews and landings. Models
produced a similarity in estimates to those of NMFS
through 1980, but a divergence since that time. The study
noted that since 1980 there has been substantial
underestimation of "boat" effort and overestimation of
"vessel" effort because of non-proportional interviews
between these two sectors. The authors estimate that
during the period 1965-1993 inshore effort (as nominal
days fished) tripled, but boat interviews declined. In
contrast offshore effort doubled, but vessel interviews
were proportionally too high in the estimates. (See
Nance
1992
and 1995 below; this section).
- Gulf
and South Atlantic Fisheries Development Foundation.
1994. Organization and management of a Gulf of Mexico and
South Atlantic Ocean fishery bycatch management program
(Year II). Saltonstall-Kennedy Grant Program, Final
report to the National Marine Fisheries Service (Award
NA37FD0032) by the Foundation (Ste. 997, 5401 W. Kennedy,
Tampa, FL 33609).
- As
part of this grant, observers logged 744 days on 63
commercial fishing trips gathering bycatch data for
characterization of the catch and evaluation of various
BRDs under actual operating conditions. A total of 362
nets were sampled for characterization, and 653 tows
compared the catch of a "control" (without a BRD) net to
the catch of a BRD-equipped net. The report notes that
finfish comprised 67 percent of the catch by weight,
while shrimp represented 19 percent; no South Atlantic
characterization data were available for analysis. Red
snapper were noted to make up less than 1 percent of the
catch by weight. BRD testing under this project is
reported under the "Bycatch Reduction" section of this
report. See also NMFS 1995 under this section for more
detailed characterization analyses completed using the
entire data set, including foundation and other research
efforts.
- Huner,
B., and G. Faulkner. 1995. Energy conservation in the
Louisiana shrimp trawling industry. Final report to the
Louisiana Dept. Nat. Resources, Energy Div., P.O. Box
44156, Baton Rouge, LA 70804
- Focusing
on various webbing materials (spectra, knotted, and
unknotted polypropylene), this report notes that shrimp
catch was similar among webbing types as was finfish
catch. Fish to shrimp ratios were 2.2 lb fish to 1 lb of
shrimp.
- Keiser,
R.K. Jr. 1976. Species composition, magnitude, and
utilization of the incidental catch of the South Carolina
shrimp fishery. Technical Report 16, South Carolina
Marine Resources Center, Charleston, SC.
- A
total of 294 tows from 120 trips aboard commercial shrimp
boats ranging in length from 35 to 75 feet were sampled
in 1974 and 1975. Monthly bycatch to shrimp ratios were
1:1 to 3:1. Fish CPUE ranged from 15 kg/hr to 244 kg/hr
while shrimp ranged from 17 to 160 kg/hr. A total of 105
fish species were identified, and only a few species
comprised the majority of the catch. Mean total lengths
of 25 species ranged from 6.9 to 18.6 cm. Sciaenids made
up from 50-80 percent of the catch; spot was the most
abundant making up over 30 percent of the yearly catch,
followed by star drum at 12 percent, and Atlantic croaker
was the fourth most abundant. This report includes
numerous tables and figures representing the catch
analyses, and provides detailed discussions of the catch
and implications of its potential for better
utilization.
- Keiser,
R.K. Jr. 1977. The incidental catch from commercial
shrimp trawlers of the South Atlantic states. South
Carolina Marine Resources Center, Technical Report 26,
South Carolina Wildl. & Marine Resources Dept.,
Charleston, SC 29412.
- This
report documented, through available literature, the
catch in shrimp trawls for the South Atlantic states,
North Carolina to Florida. Fish to heads-on shrimp ratios
ranged from 1.2:1 to 4:1. For North Carolina, results
ranged as high as 100:1, but the average was 4:1. Night
time ratios were lower than daytime ratios; not because
less fish were caught at night, but because more shrimp
(17 percent vs. 13 percent of catch) were taken at night.
The two most common species, spot and Atlantic croaker,
comprised 63 percent of the finfish catch. For South
Carolina, ratios ranged from 2.6:1 in summer to 1.2:1 in
fall. Spot and Atlantic croaker were the dominant
species, comprising 50 percent of the catch. Bycatch
ratios in Georgia were estimated at approximately 2.5:1,
and spot, Atlantic croaker, star drum, and bay anchovy
were the dominant species. In the Atlantic Florida
region, the ratio was approximately 3.8:1. No current
estimates of species composition were cited.
- Martinez,
E.X., and J.M. Nance. 1993. Trawling Bycatch in the
Galveston Bay System. The Galveston Bay National Estuary
Program Publication GBNEP-34. NMFS/SEFSC, Galveston,
Texas.
- The
characterization study, performed by the National Marine
Fishery Service (NMFS) Galveston Laboratory, was
conducted in three phases: 1) a review of historical
bycatch studies, 2) initiation of new data collection
efforts on commercial vessels and 3) a comparison of new
data collected with fishery-independent surveys of the
Texas Parks and Wildlife Department. Three historical
studies regarding bycatch in Galveston Bay were
identified and reviewed. Matlock (1982) analyzed the
catch of gulf and southern flounder Paralichthys
albigutta and P. lethostigma, respectively) in
34 tows from a commercial shrimp vessel during
April-November 1978. He concluded bycatch of flounder was
lower in Galveston Bay than in other Texas bay systems.
Lamkin (1984) reviewed bycatch in tows sampled from one
bait shrimp vessel in lower and West Galveston Bay during
July 1981-June 1982. He identified 56 bycatch species (52
finfish species) from 62 samples (34 trips); bycatch
averaged 27.2 percent of total catch weight (range =
17-42 percent). Lamkin observed that five species
accounted for about 71 percent of the bycatch by number
and 65 percent of bycatch biomass. These species included
Atlantic croaker, sand seatrout, blue crab, spot and gulf
menhaden. Bessette (1985) accompanied six different bait
shrimpers throughout five areas of Galveston Bay during
May-November 1984. In 107 tows sampled, Bessette
identified 66 species of finfish and eight invertebrates.
Bycatch comprised 3-99 percent of total catch by weight
with an average of 65 percent. Bessette observed 4.1 kg
of fish captured for each kg of shrimp landed.
New
data collection was initiated in 1992 by NMFS. A total of
296 samples were collected during March-November 1992 and
85 finfish species and 49 invertebrates were identified.
Overall, bycatch species comprised 38 percent of the
catch by number and averaged 71 percent of total catch by
weight. Nine species (of 134 total) accounted for 80
percent of the bycatch by number and 79 percent by
weight. These included gulf menhaden, Atlantic croaker,
spot, cutlassfish, sand seatrout, bay anchovy, Atlantic
brief squid, hardhead catfish and blue crab. Gulf
menhaden, Atlantic croaker and sand seatrout were the
only species of commercial or recreational value which
were captured in great numbers.
- Nance,
J.M. 1992. Estimation of effort in the Gulf of Mexico
shrimp fishery. NOAA Tech. Mem., NMFS-SEFSC-300.
- Given
the size of the shrimp fleet in the Gulf of Mexico,
including inshore, nearshore, and offshore vessels,
actual documentation of effort is impossible. Boats and
vessels are interviewed by NMFS port agents to gather
information concerning specific trips in the various
area-season-depth matrix. These data are then used to
calculate effort for the fleet by dividing the average
CPUE (catch per fishing day) of these interview trips
into the total landings for the particular region,
resulting in an estimate of effort for the fishery. When
specific information is lacking for a particular cell in
the matrix, the average historical value for that cell is
used in a model to estimate the catch for that particular
cell for the given time period. From 1969-1989, effort of
the Gulf fleet has increased from approximately 125,000
days fished to about 300,000 days fished. The greatest
increases are in offshore effort, especially in the north
central area (areas 10-12) and off Texas (areas 18-21).
Effort in Louisiana shifted in the mid-70's from inshore
to offshore while inshore effort in the north central
Gulf and off Texas increased. Conversely, inshore effort
in Louisiana dropped, but offshore effort increased
markedly. (See
Griffin and Shah,
1995 for comparison; this section).
- Nance,
J.M. 1993. Effort trends for the Gulf of Mexico shrimp
fishery. NOAA Technical Memorandum, NMFS SEFSC
337.
- Two
types of data are used to estimate shrimp effort: dealer
data (landings through a recognized dealer) and interview
data (actual interviews with captains following a fishing
trip). The fishing trip is considered a unit of effort;
in 1992 an estimated 291,954 trips occurred. Interviews
have declined substantially from about 20,000 to 6,000
since the early 1980's due to several logistic problems.
For offshore efforts, average days fished per trip for
all areas have increased since 1980 from 3 - 6 days (a
day is towing trawls for 24 hours; this may include
several actual days fishing effort {i.e. four, 6-hr tows
made over a 2-day period would equal 1 netday}), and CPUE
has declined slightly since the early 1980's for all
areas. For nearshore areas, days fished have increased
over time, driven by increases in Louisiana which logs
nearly two to three times as much nearshore effort as the
rest of the Gulf combined. Offshore boat and vessel trips
have been stable over time, although offshore vessel
trips in the eastern Gulf have declined. The data in this
report are presented in several subunits by statistical
area groups and specific groups of ports.
- Nance,
J.M. 1993. Shrimp trawl bycatch characterization
study.(93NMFS20). NMFS/SEFC Galveston Laboratory,
Galveston, Texas.
- This
document presents the results obtained by an onboard
observer program. Sixty-seven trips were completed from
May 1992 through September 1993. Fourteen of the trips
were along the eastern coast of the United States, while
the other 53 trips were in the Gulf of Mexico. Trip
length varied from 1 - 27 days. A total of 770 sea days
were used to collect the data from 1,027 tows. One
hundred and forty-five of the sea days were along the
eastern coast of the United States, and the other 625 sea
days were in the Gulf. Of the 625 sea days in the Gulf,
59 were off Florida, 67 were off Alabama/Mississippi, 340
were off Louisiana, and 159 were off Texas. Thirty-nine
different vessels were used in the study. NMFS-approved
observers were used to collect the trawl haul subsamples
and record the data.
Appendix
I summarizes the findings by season and statistical area;
Appendix II summarizes the data by season, statistical
area, and depth; Appendix III gives data for red snapper
by season, statistical area, and depth. In the Gulf of
Mexico, 10 species accounted for 71 percent of the
bycatch by weight and 68 percent by number in the trawls
sampled. Dominant among these were Atlantic croaker and
longspine porgy. This work was later incorporated into
the industry/government cooperative bycatch research
program database (see National Marine Fisheries
Service, 1995 below).
- National
Marine Fisheries Service. 1995. Cooperative research
program addressing finfish bycatch in the Gulf of Mexico
and South Atlantic shrimp fisheries: a report to
Congress, April 1995. USDOC, NOAA, NMFS. National Marine
Fisheries Service, 9721 Executive Center Drive, St.
Petersburg, FL 33702
- The
document outlines the goals, objectives, and results to
date for a federally mandated bycatch reduction research
program. Eight program objectives are discussed in detail
-- characterization, improved stock assessments,
evaluation of bycatch reduction devices (BRDs), non-gear
options, management options, information and education
programs, identification of other mortality, and
development of a centralized database. This booklet
provides a good overview of the program and the status of
the research. Substantial advances have been made in
characterizing the catch through a large-scale
fishery-dependent survey. Over 450 taxa have been
identified in Gulf of Mexico trawls, with an average
catch of 27 kg/net-hour. Shrimp represented 16 percent of
the catch by weight; fish, 68 percent. The 150 taxa in
South Atlantic shrimp trawls constituted a catch of 29
kg/net-hour of which shrimp represented 20 percent and
fish represented 47 percent. These fish to shrimp ratios
(4.25:1 for the Gulf and 2.4:1 for the South Atlantic)
are much lower than previous (older) estimates of 10:1.
Results of two types of bycatch reduction devices (BRDs)
are summarized: fisheyes and expanded mesh-extended
funnel. Both have minimal shrimp loss with substantial
finfish reduction including reductions for key species of
concern such as red snapper and weakfish. Additional
information is found in this report under
"Bycatch
Reduction Devices".
- Nichols,
S., A. Shaw, G.J. Pellegrin, Jr., and K. Mullen. 1987.
Estimates of shrimp fleet bycatch for thirteen finfish
species in the offshore waters of the U.S. Gulf of
Mexico. National Marine Fisheries Service, P.O. Drawer
1207, Pascagoula, MS 39568.
- This
report provided estimates of the offshore catch from
1971-1985 for some commonly occurring fish species,
including Atlantic croaker (1-2 billion individuals),
spot (150-200 million), longspined porgy (250 million),
red snapper (10-15 million), king mackerel (200-250
thousand), Spanish mackerel (ca. 1.5 million), and red
drum (120,000), as part of the shrimp catch (100-120
million individuals).
- Nichols,
S., A. Shaw, G.J. Pellegrin Jr., and K. Mullen. 1990.
Updated estimates of shrimp fleet bycatch in the offshore
waters of the U.S. Gulf of Mexico 1972-1989. National
Marine Fisheries Service, P.O. Drawer 1207, Pascagoula,
MS 39568.
- This
report updated an earlier similar report (Nichols et al.
1987), noting an error in the earlier calculations, and
provided substantially different values for the species.
Total offshore catch of finfish was ca. 400 million
pounds annually. The annual catch in numbers for some
commonly occurring species included Atlantic croaker (5-6
billion individuals), spot (600 million), seatrouts (two
species, 1.5 billion), longspined porgy (1 billion), red
snapper (25 million), king mackerel (1 million), Spanish
mackerel (3 million), and red drum (20,000), as part of
the shrimp catch (100-120 million
individuals).
- Pellegrin,
G. Jr. 1982. Fish discards from the southeastern United
States shrimp fishery. pp. 51-54 In: Fish
by-catch...bonus from the sea; report of a technical
consultation on shrimp by-catch utilization held in
Georgetown, Guyana, 27-30 October 1981. FAO and
International Development Research Centre, Ottawa (IDRC
198-e).
- This
report divided the Gulf of Mexico into four zones and the
South Atlantic into four zones and noted the bycatch
taken in each area. Bycatch ratios in the South Atlantic
were highest in North Carolina (4:1) and lowest in South
Carolina (1.6:1). For the Gulf, bycatch ratios west of
Mobile were substantially higher (ca. 15:1) than in the
eastern Gulf (5-6:1). The estimate of total discard on an
annual basis was 33,000 tons for the South Atlantic and
was estimated to be 15 times higher in the Gulf of Mexico
due to its larger amount of estuarine-dependent
fauna.
- Pellegrin,
G.J. Jr., S.B. Drummond, and R.S. Ford Jr. (no date). The
incidental catch of fish by the northern Gulf of Mexico
shrimp fleet. Draft manuscript by the National Marine
Fisheries Service, P.O. Drawer 1207, Pascagoula, MS
39568.
- At-sea
observers collected data aboard commercial shrimp vessels
during 1972 - 1980. The highest bycatch to shrimp
(heads-on) ratio by weight occurred during cool weather
(21.1:1), and the lowest occurred in the same area in
offshore waters during both cool and warm seasons (2.0:1)
{This is confusing in the draft; in the introductory
material it notes the area as "eastern Gulf" but later in
the document notes the same information related to "area
4" which is all waters west of 92 degrees longitude --
Texas and western Louisiana. This latter region is
likelier to be correct}. Annual mean ratio for the area
was 10.3:1. Sciaenids dominated the catch at 52.5
percent, with Atlantic croaker at 33.6 percent. The
authors estimate that the northern Gulf fleet catches
576,000 tons of fish annually with nearly 80 percent of
this caught during the warmer months. Of interest is the
note that red snapper comprised less than 0.4 percent of
the total finfish weight. This is a similar value to more
recent bycatch observer studies.
- Perret,
W.S., P.E. Bowman, and L.B. Savoie. 1996. Bycatch in the
shrimp fishery of Louisiana. pp. 137-143 In:
Baxter, B., and S. Keller (eds.). Bycatch: considerations
for today and tomorrow. Alaska Sea Grant College Program
Report No. 96-03, University of Alaska,
Fairbanks.
- Fishery-independent
surveys of Louisiana territorial waters have continued
since 1967 using a 4.9 m otter trawl (flat net) towed for
10 minutes at set stations. This data set provides
long-term information to assess any changes in abundance.
268 species including 183 fishes, 62 crustaceans, 14
mollusks, and 9 miscellaneous groups comprise the
database. Several dominant or fishery important species
were examined -- blue crab: high annual
fluctuation with long-term trend of abundance nearly
doubling over the study period; bay anchovy: high
annual fluctuation in abundance with an increasing trend
over time; spotted seatrout: catch rates were so
low that no trends could be determined, but CPUE was
stable over time; sand seatrout: general increase
which has nearly tripled the relative abundance of this
species in the samples over the study period; Gulf
menhaden: long-term trend of slight but steady
increase with high levels of fluctuation during the early
1970's through mid-1980's. Two new gears were also
examined -- skimmer and butterfly nets. Both have a lower
bycatch to shrimp ratio than the standard shrimp otter
trawl, and because of the way the catch is handled, much
of the bycatch is released alive.
- Pueser,
R. (ed.). 1996. Estimates of finfish bycatch in the South
Atlantic shrimp fishery. Final Report, SEAMAP South
Atlantic Committee Shrimp Bycatch Work Group (NOAA Award
NA47FS0035), submitted to the Atlantic States Marine
Fisheries Commission, 1444 Eye St., NW, Sixth Floor,
Washington D.C. 20005.
- This
report summarizes the catch in the South Atlantic shrimp
fishery including background information on the biology
of the shrimps, the fishery, and the current status of
management efforts. Landings data by state along with
effort information were used to estimate the bycatch in
the fishery based on the NMFS Bycatch Research Program
results. Atlantic croaker and spot were the dominant
species in most area-season-year analyses, but weakfish
were abundant in North Carolina during summer and fall,
and in the offshore Florida area in winter. Limitations
in this report were noted by the editor as: 1)
differences between landings records and observer data as
to the definitionof a "trip"; and 2) small sample sizes
for many strata. Although the document contains detailed
analyses and extrapolations for each area-season-year for
the bycatch taken by the fishery, the editor notes that
nothing in this report should be used to represent the
actual estimate of bycatch in the southeast
Atlantic.
- South
Carolina Department of Natural Resources. 1996. Results
of trawling efforts in the coastal habitat of the South
Atlantic Bight, FY-1995. SEAMAP-South Atlantic Annual
Report. South Carolina Dept. Nat. Resources, P.O. Box
12559, Charleston, SC 29422
- Information
was collected on the composition, abundance, and biomass
of shrimp trawl catches, as well as seasonal and regional
trends in environmental parameters during 1995. Sampling
collected 202 species. Inner strata sampling of 234 trawl
tows produced 186 species of which 142 were fishes.
Twenty-seven trawl samples in outer strata produced 135
species, of which 98 were fishes. Spot and Atlantic
croaker made up 38 percent of number of individuals and
20 percent of the biomass. White shrimp was third in
abundance. Weakfish densities were high (46
individuals/hectare) in Raleigh Bay, but were
substantially less for more southerly regions. In South
Carolina, Georgia, and Florida, the densities were less
than five fish per hectare except for a fall spike of
larger fish off Florida (7.78 fish/hectare).
- Stender,
B.W., and C.A. Barans. 1991. A comparison of the catch
from two types of shrimp nets off South Carolina, USA.
Saltonstall-Kennedy Program Final Report (GASAFDI #
40-11-44769/22494) (Award #NA90AA-H-SK006) by the South
Carolina Wildl. and Mar. Resource Dept., P.O. Box 12559,
Charleston, SC 29422.
- In
tests conducted off Charleston, SC, catch rates between a
two-seam net and a tongue trawl were compared. The study
documented differences in catch rates for eight of 182
taxa collected. Bycatch in the tongue trawl, which has a
higher vertical opening, was substantially higher.
Catches in both nets were dominated by sciaenids. Bycatch
to shrimp ratios in this fishery-independent study were
much higher than that documented for the fishery.
Substantial catches of Spanish and king mackerels were
taken during this study.
- Wallace,
R.K., and W. Hosking. 1991. Documentation of bycatch from
small inshore shrimp vessels and evaluation of
appropriate bycatch reduction devices. Final Report (NOAA
Grant Award NA90AAH-SK120) by the Auburn Marine Extension
and Research Center, 4170 Commanders Drive, Mobile, AL
36615.
- This
report combined field sampling (fishery-independent) with
a mail survey to assess the bycatch and effort of the
small boat recreational fishery. From the field sampling
bycatch to shrimp ratios were nearly 15:1 (range 1.2:1 to
93:1). Four hundred seventy-four surveys were returned
(19.5 percent); usable surveys indicated that, in 1990,
recreational shrimpers averaged 5.6 trips, 4.3 tows per
trip, and 38.2 minutes per tow equaling approximately
40,000 net-hours. Based on their estimates of 16.2 kg of
bycatch per net-hour, Alabama recreational shrimping
contributed to an estimated 648,000 kg of bycatch and
49,000 kg of shrimp for a 13:1 bycatch to shrimp ratio.
Tests of bycatch reduction devices included "fish
shooter" (a slit in the bag), and two sizes of "fisheyes"
placed on the bottom of the bag. The fisheyes in this
configuration reduced fish, but lost 14 and 19 percent of
the shrimp.
Bycatch
from recreational shrimping was estimated from
fishery-independent trawling and through a survey of
licensed recreational shrimpers in Alabama. The mean fish
bycatch was 5.4 kg per 20-minute tow and contained 426
fish primarily from three families (Sciaenidae,
Engraulidae, Clupeidae). Based on the survey of
recreational effort, the total fish bycatch was estimated
at 603,000 kg or 47.6 million fish. Tests of two bycatch
reduction devices resulted in significant reduction in
bycatch for the Florida Fish Eye, but no significant
reduction for the Fish Shooter.
Species-Specific
Characterization Studies:
- Gregory,
D.R. Jr. (Draft) An annotated bibliography of literature
pertaining to reef fish bycatch in shrimp trawls. Gulf of
Mexico Fishery Management Council. 1988.
- Thirteen
documents, both published and unpublished, are listed
with brief synopses of their contents. Most of the listed
documents are unpublished, but addresses or contacts are
listed. Some of the documents are also listed in this
report, but copies of the unpublished material, some of
which appears to be expanded correspondence to the Gulf
Council, were not requested for review and inclusion in
this bibliography.
- Gutherz,
E.J., and G.J. Pellegrin. 1986. Report on snapper-grouper
mortality by shrimp trawlers in the U.S. Gulf of Mexico.
(Unpublished report to Gulf of Mexico Fishery
Management Council.)
- This
document is more formally presented in Gutherz and
Pellegrin 1988, listed below. Although the addition of
groupers to this report would appear to provide
additional information, that information is contained in
two sentences on page 7: "Small gag (Mycteroperca
microlepis) have been taken infrequently by bait
shrimpers in Tampa Bay and other Florida bay systems, but
most groupers reside in areas not suitable for trawling.
Commercial shrimping activities, therefore, probably
exert little influence on populations of
Mycteroperca and Epinephelus groupers."
Otherwise, Gutherz, and Pellegrin 1988 is a more
obtainable reference.
- Gutherz,
E.J., and G.J. Pellegrin. 1988. Estimate of the catch of
red snapper, Lutjanus campechanus. by shrimp
trawlers in the U.S. Gulf of Mexico. Fisheries.
50(1):17-25.
- In
an analysis of 1972-1983 resource survey
(fishery-independent) and 1972-1981 commercial fishery
(fishery-dependent) data sets, this study indicated that
resource survey data shows a much higher catch and catch
rate of juvenile red snapper than that of actual catch by
the shrimp fishery. The two methods both indicated that
the majority of snapper are taken from September through
November, and catches were primarily west of the
Mississippi River delta. By region, highest catch rates
occurred off Texas. By depth, highest catch rates were in
the 11-20 fathom region; few juvenile red snapper were
taken shallower than 10 fm, or deeper than 30 fm. Based
on the commercial fishery data, annual catch appeared to
be about 5 million juvenile red snapper.
- McCarty,
G. 1995. Biological benefits of the 200-mile closure for
red Snapper and brown shrimp. (GMFMC Briefing Book
Addition, Tab l, No. 7). Texas Parks and Wildlife
Department, Austin, Texas.
- The
summer closure of the shrimping grounds off Texas has
been monitored through a Texas Parks and Wildlife
Department (TPWD) sampling program since 1978. From
1977-1980 the closure distance was 9 miles; from
1986-1988, 15 miles; and from 1981-1985 and 1989-1993,
200 miles. Data for this study come from the TPWD
standardized fishery-independent monitoring program. The
mean number per hour of juvenile red snapper caught in
trawls was significantly greater when the 200-mile
closure was in effect, showing a greater than 400 percent
increase over the years with a 15-mile closure. No
significant differences were found when comparing the
years following a 9-mile and a 15-mile closure. For the
years when the 200-mile closure was in effect there were
significant increases in the number of juvenile red
snapper in trawl samples and in the number of juvenile
brown shrimp in the estuaries.
- Nichols,
S. 1990. The spatial and temporal distribution of the
bycatch of red snapper by the shrimp fishery in the
offshore waters of the U.S. Gulf of Mexico.
(Unpublished report of the National Marine Fisheries
Service, Pascagoula Lab, P.O. Drawer 1207, Pascagoula, MS
39568.)
- The
report provides estimates of red snapper abundance
according to an area-season matrix based on
fishery-independent and fishery-dependent sources
collected from 1972 - 1982. The purpose of the report was
to investigate the possibility of area or season closures
to reduce the bycatch mortality on red snapper. The
general conclusion was that either area or seasonal
closures would only transfer the mortality to another
cell in the matrix. The report notes that predicting
fleet behavior was unsuccessful. The fleet did not
respond to regional differences in shrimp catch rates in
a predictable manner; cost-benefits ratios and personal
preferences may influence the extent of fleet migrations.
Thus, without any predictability, such closures would
likely have limited benefit.
Shrimp
Trawl Bycatch Reduction Implications:
- Alverson,
D.L., M.H. Freeber, S.A. Murawski, and J.G. Pope. 1994. A
global assessment of fisheries bycatch and discards. FAO
(Food and Agricultural Organization of the United
Nations) Technical Paper 339.
- Shrimp
trawls are only one of many fishery efforts categorized
in this report, however they are identified as the
dominant source of bycatch and discard in world
fisheries. Globally, shrimp fishing is categorized as
having a 5.2:1 bycatch to shrimp ratio, with the highest
catch ratio from Trinidad at about 15:1. The Gulf of
Mexico ranked fifth at 10.3:1. This extensive document is
divided into several sections addressing various issues
including: estimates of bycatch and discard; biological,
economic, socio-cultural, and ecological impacts; a
summary of international policies; and a detailed
discussion on various options that can help achieve
bycatch reduction.
- Colura.
R.L., and B.W. Bumguardner. 1996. The Texas shrimp
industry salt-box catch separation procedure effect on
bycatch survival. (MARFIN NA57FF0047). Texas Parks and
Wildlife Department, Perry R. Bass Marine Fisheries
Research Station, Palacios, Texas.
- The
use of salt-boxes by the Texas shrimping industry to
separate bycatch from shrimp was described and bycatch
survival evaluated. Commercial and bait shrimpers were
interviewed about their use of salt-boxes. Bioassays were
conducted for lethal exposure time of important sport and
commercial species. Bycatch samples were taken from
trawling operations to determine bycatch survival for the
salt-box and no salt-box separation methods. Salt-box
salinities averaged 67 ppt to which bycatch was exposed
an average of 1.7 minutes. Red drum was the most easily
affected species requiring 17 minutes of exposure to 70
ppt to kill 59 percent within 48 hours. Survival was
mainly affected by "cull" time on the boat deck and
length of trawling time rather than the use of
salt-boxes.
- Fowle,
S., and R. Bierce (eds.). 1992. Proceedings of the shrimp
trawl bycatch workshop; November 22-23, 1991. Center for
Marine Conservation.
- These
proceedings provide relatively complete transcripts of
oral presentations made by a variety of speakers on three
topics: 1) Effects of shrimp trawl bycatch on finfish
populations and ecosystems (Nichols, Browder, Muller,
Teehan presenters); 2) Socioeconomic effects of shrimp
trawl bycatch (Ward, Griffin, Ditton, Dyer, Margavio
presenters), and 3) shrimp bycatch and fishery management
(Swingle, Seidel, Apricio, Easley, Gauvin presenters).
Other reports covering this material, by many of these
presenters, are included in this bibliography. This
workshop was held early during the development of the
NMFS Shrimp Trawl Bycatch Reduction Research Program, and
highlighted the various concerns about bycatch and its
implications in fishery management. Many of the
presentations discussed how to address the issue, not the
results of what had been accomplished. At this stage of
the program, little information was available as to the
most feasible ways to actually accomplish bycatch
reduction.
- Griffin,
W.L., D. Tolman, and C. Oliver. 1993. Economic impacts of
TEDs on the shrimp production sector. Society and Natural
Resources, Vol. 6:291-308.
- A
simulation modeling technique is used which estimates the
changes in landings, revenues, costs, and the economic
rents. A base scenario in which no TEDs are used is
compared with five different scenarios where the TED is
used by vessels in the Gulf of Mexico. The analysis was
based on a single year impact. The implementation of the
TED comes with costs to the vessel owners and crew. All
other things remaining equal, some vessel owners and crew
will leave the industry depending on how successful they
are at learning to use the TED effectively.
- Gulf
of Mexico Fishery Management Council. 1990. Report of the
workshop to evaluate potential management alternatives
for reducing directed effort and shrimp trawl bycatch of
red snapper.
- A
workshop of interested and involved parties was held in
Pascagoula, MS, in May of 1990 to address shrimp trawling
and red snapper bycatch. Participants concluded that
reduction in shrimp bycatch of about 60 percent of the
red snapper catch would be required to increase ABC
(allowable biological catch) for red snapper fisheries.
Options to achieve this reduction included area-season
closures and TED modifications. These options are
discussed in some detail, especially the various
area-season closures that could be
implemented.
- Hendrickson,
H.M., and W.L. Griffin. 1993. An analysis of management
policies for reducing shrimp by-catch in the Gulf of
Mexico. North American Journal of Fisheries Management
13:686-697.
- The
general bioeconomic fisheries simulation was used to
estimate the changes in economic rent and bycatch of red
snapper, king mackerel, and Atlantic croaker that would
result under two fishery management policies: use of
bycatch reduction devices (BRDs) and season-area
closures. The BRDs were found to be more effective than
closures at reducing bycatch and less costly to
shrimpers. Under the BRD scenarios, red snapper discards
were reduced 20.2-42.5 percent, king mackerel discards
fell approximately 89 percent, and Atlantic croaker
discards fell about 45 percent. Under closure policies,
the change in discards was a 2.1-15 percent decline for
red snapper, a 1.9 percent increase to a 39.3 percent
decrease for king mackerel, and a 0.1-12.9 percent
decline for Atlantic croaker.
- Kennelly,
S.J. (draft manuscript). The issue of by-catch in
Australia's trawl fisheries. State of the Marine
Environment Report for Australia: Technical
Annex.
- Bycatch
is defined as two types: interfishery bycatch where an
important fishery species is taken as unwanted catch in a
fishery targeting another species, and intrafishery
bycatch where undersized (or oversized) individuals of
the target species are taken. The report notes the need
to characterize the catch through fishery-dependent
surveys, and develop good stock assessments through
fishery-independent faunal surveys. The latter is
essential in interpreting the impact of bycatch on the
biomass of the "impacted" stocks. Changes occur in faunal
composition due to trawling. Therefore, the impacts on
benthic communities through habitat alteration must be
identified. The report notes that much of the finfish
bycatch suffers mortality, but the crustacean bycatch
likely survives. Removal of the fish predators on shrimp
should positively impact shrimp stocks. On the other
hand, discards probably do little to benefit shrimp
stocks as they do not prey or scavenge on discards, but
other species, such as crabs, sharks, pelagic fishes do;
thus, discard may actually benefit the stock of these
populations. Better utilization of bycatch is not often
possible, but management of bycatch is an increasing
concern. The report highlights standard mechanisms such
as closures or gear modifications, but notes that
regional issues must drive the system to ensure that
measures are effective and practical to specific local
situations.
- Lunz,
G.R., J.L. McHugh, E.W. Roelofs, R.E. Tiller, and C.E.
Atkinson. 1951. The destruction of small fish by the
shrimp trawlers in Pamlico Sound, North Carolina. Report
to the Chesapeake Bay and South Atlantic sections,
Atlantic States Marine Fisheries
Commission.
- Noting
a decline in the catch of several commercial species,
this report attributes the declines to bycatch of
juvenile finfishes by shrimp trawlers, although it notes
that such mortality is only accountable if it contributes
to additional mortality from natural causes instead of
just replacing natural mortality. Interestingly, bycatch
mortality and its effect on commercial finfishes
was the concern of this period, and it was written up in
several newspapers and other general media outlets. This
report debunks some of the hyped-up stories generated by
such media coverage. The report concludes that such
fluctuations in abundance may or may not be from
incidental mortalities, and do happen occasionally.
Several appendix documents discuss specific studies: one
of note measured fish to shrimp ratios which in July were
2 pounds of shrimp per pound of fish, but by the end of
August were 1 pound of shrimp to 3 pounds of fish. A
second study listed fish/shrimp ratios at 3:1 to 15:1 in
an October sampling period.
- Goodyear,
C.P. 1992. Red snappers in U.S. waters of the Gulf of
Mexico. Contribution MIA91/92-70 of the NMFS Southeast
Fisheries Center, Miami Lab, 75 Virginia Beach Drive,
Miami, FL 33149.
- This
stock assessment was provided for Gulf of Mexico Fishery
Management Council consideration as to options for both
the red snapper fishery and the shrimp fishery. The
assessment estimated that survival of age-0 and age-I
fish to the directed fishery at later ages is reduced by
83 percent because of trawling. As much as one-third to
one-half of the age-0 class suffers mortality from
trawling. The report notes that without 50 percent
reductions in bycatch mortality on these age groups, the
snapper fishery cannot continue with current total
allowable catches (TACs).
- Goodyear,
C.P. 1994. Red snappers in U.S. waters of the Gulf of
Mexico. Contribution MIA93/94-63 of the NMFS Southeast
Fisheries Center, Miami Lab, 75 Virginia Beach Drive,
Miami, FL 33149.
- This
stock assessment was provided for Gulf of Mexico Fishery
Management Council consideration as to options for both
the red snapper fishery and the shrimp fishery. This
assessment estimated that survival of age-0 and age-I
fish to the directed fishery at later ages is reduced by
82 percent because of trawling. As much as one-third to
one-half of the age-0 class suffers mortality from
trawling. The report notes that without 50 percent
reductions in bycatch mortality on these age groups, the
snapper fishery cannot continue with current TACs,
especially due to over-harvesting the quotas by both
recreational and commercial sectors. These projections
are more pessimistic than the previous
estimates.
- Goodyear,
C.P. 1995. Red snappers in U.S. waters of the Gulf of
Mexico. Contribution MIA995/96-05 of the NMFS Southeast
Fisheries Center, Miami Lab, 75 Virginia Beach Drive,
Miami, FL 33149.
- This
stock assessment was provided for Gulf of Mexico Fishery
Management Council consideration as to options for both
the red snapper fishery and the shrimp fishery. This
assessment estimated that survival of age-0 and age-I
fish to the directed fishery at later ages is reduced by
80-88 percent because of trawling. As much as one-third
to one-half of the age-0 class suffers mortality from
trawling. The report notes that without 50 percent
reductions in bycatch mortality on these age groups, the
snapper fishery cannot continue with current TACs,
especially due to excessive over-harvesting by the
recreational sector. If the reductions are met, then a
quota of approximately 10 million pounds could be taken
and still meet recovery target date
requirements.
- Hoar,
P., J. Hoey, J. Nance, and C. Nelson (eds.) 1992. A
research plan addressing finfish bycatch in the Gulf of
Mexico and South Atlantic shrimp fisheries. Gulf and
South Atlantic Fisheries Development Foundation, 5401 W.
Kennedy, Tampa, FL 33609.
- To
address the concerns of a multitude of user and interest
groups associated with the bycatch issue in the
southeastern shrimp fishery, this consensus document
expanded upon a "research requirements" document
developed by NMFS (1991), and outlined a strategic
research plan that would address the bycatch issue in the
shrimp fishery. This included eight program objectives:
1) update bycatch estimates; 2) improve stock
assessments; 3) identify and develop gear options for
bycatch reduction; 4) identify and evaluate non-gear
options; 5) evaluate biological, social, and economic
impacts of management options; 6) allow for
multi-organizational oversight and information transfer
opportunities; 7) identify other sources of fishing
mortality; and 8) develop a centralized database. These
eight objectives included 17 specific tasks that would
require 44 different projects to be completed. The
funding costs for these objectives, tasks, and projects
were estimated, and the priorities for each project were
identified.
- Jones,
R.P. (ed.). 1993. International conference on shrimp
bycatch (proceedings) {May 24-27, 1992}. Southeastern
Fisheries Association (under NOAA/NMFS Award
NA90AAHMF7345), 312 E. Georgia St., Tallahassee, FL
32301.
- This
was one of several conferences that initially addressed
the issue of southeast U.S. shrimp trawl bycatch: its
quantity, composition, distribution, and impacts on
marine resources. The conference brought together
scientists, management agencies, industry, and other
stakeholders to discuss the bycatch situation worldwide;
the focus of most of the presentations was on the
southeastern U.S. Presentations from all the represented
groups focused on the qualitative and quantitative
aspects of bycatch. Concerns focused on defining the goal
of bycatch reduction, the quality and quantity of data
that existed, how to improve those data through
cooperative partnerships, working toward simple
solutions, and accepting current reductions through
existing gear modifications. Also discussed are some
techniques that have been used to reduce bycatch through
fishing effort changes, gear modifications,
etc.
- Martinez,
E.X., J.M. Nance, and R.J. Zimmerman. 1996. A model for
assessment of ecological interactions among living marine
resources in the Gulf of Mexico: implications for bycatch
management and shrimp production. Executive summary of a
report to the Gulf of Mexico Fishery Management
Council.
- As
an update of an earlier modeling attempt by Sheridan et
al. (1984), an ecosystem-based model to assess the
impacts of bycatch reduction and shrimp production
indicated that the release of additional fish which are
predators on shrimp may impact the shrimp stock. Only 14
of 161 fish species examined have been identified as
predators on shrimp; however these include some of the
more abundant species taken in shrimp trawls, including
the Atlantic croaker and seatrouts. Sand seatrouts
represent the dominant shrimp predator. Using a
nitrogen-cycle based model and looking at the northwest
Gulf of Mexico (west of Mobile Bay) where the majority of
the sciaenid fish predators exist, various scenarios were
developed depending on the amount of bycatch reduced.
With a 10 percent reduction of all fish species
equally by number, shrimp stock would decline only 1
percent (it is important to note here that these
shrimp values represent stock of
shrimp, not fishery yield), but with a 50 percent
reduction in catch of predatory fish, shrimp stock would
decline as much as 10 percent. Using the actual reduction
values for various finfish species, related to the
bycatch reduction gear (BRD) type, a 6-7 percent
reduction in shrimp stock would occur for "fisheye" BRDs,
and an 8 percent reduction in shrimp stock would occur
for the expanded mesh BRDs. Using various predation
rates, which change ontogenetically for various fish
species, shrimp stock would decline between 8 percent and
17 percent. Lastly, as the fish matured, and their
dietary changes moved away from shrimp, the decreased
predation would increase shrimp stock by 5 percent. The
report concludes that, on average over the last 5 years,
shrimp stock has fluctuated naturally by as much as 12
percent, thus the above estimates would fall within
normal ranges of production.
- Murray,
J.D., J.J. Bahen, and R.A. Rulifson. 1992. Management
considerations for by-catch in the North Carolina and
southeast shrimp fishery. Fisheries
17(1):21-26.
- The
document sets a background using the available
characterization studies and the impetus behind the
bycatch issue in the southeastern shrimp fishery. It
notes that with the possible exception of red snapper and
weakfish, there is no conclusive evidence that shrimp
bycatch is a biological problem. It does however note
that a recent North Carolina study (Miller et al. 1990 -
FAO Fish. Biol. Tech. Paper 314) suggests that estuarine
species do not demonstrate density-dependent responses to
juvenile mortality (increased growth or survival). The
estuaries are not saturated with larvae or young; the
limiting factor to the area is colonization, thus
juvenile bycatch may result in reduced adult populations.
The report concludes that managers have several options
such as seasonal and area closures or gear modifications
and restrictions with which to address the issue. The
article is careful to point out that many problems
encountered during TED implementation concerning poor
user and interest group interaction and communication
should be addressed when introducing bycatch reduction to
the fishing industry.
- National
Marine Fisheries Service. 1991. Shrimp trawl bycatch
research requirements. USDOC, NOAA, NMFS. National Marine
Fisheries Service, 9721 Executive Center Drive, St.
Petersburg, FL 33702
- In
response to the mandate outlined in the 1990 revision of
the Magnuson Fishery Conservation and Management Act,
NMFS developed a strategic plan outlining a research
program to address the bycatch issue in the southeastern
shrimp fishery. This initial document summarized what was
known about the quantity and composition of bycatch, how
and why it was (perceived) an issue, current research on
bycatch and its reduction, and the impacts that bycatch
reduction would have on shrimp stocks. The document noted
the need for a multi-organizational interactive and
cooperative effort to address this issue on a region-wide
basis.
- National
Marine Fisheries Service. 1995. Cooperative research
program addressing finfish bycatch in the Gulf of Mexico
and South Atlantic shrimp fisheries: a report to
Congress, April 1995. USDOC, NOAA, NMFS. National Marine
Fisheries Service, 9721 Executive Center Drive, St.
Petersburg, FL 33702
- The
document outlines the goals, objectives, and results to
date for a federally mandated bycatch reduction research
program. Eight program objectives are discussed in detail
- characterization, improved stock assessments,
evaluation of bycatch reduction devices (BRDs), non-gear
options, management options, information and education
programs, identification of other mortality, and
development of a centralized database. This booklet
provides a good overview of the program and the status of
the research. Substantial advances have been made in
characterizing the catch through a large-scale
fishery-dependent survey, and the effectiveness and
efficiency of numerous BRDs (over 80 types or
configurations) have been evaluated. Two types of BRDs
have been identified as meeting program goals: expanded
mesh-extended funnel (large meshes which allow escapement
surrounding a funnel), and fisheyes (metal-framed cones
which provide a permanent hole for escapement). The
report also highlights some socio-economic work that has
been completed characterizing the fishery and the
fishers.
- Nichols,
S., J. Nance, C.P. Goodyear, A. Shah, and J. Watson.
1995. Some considerations in determining bycatch
reduction requirements. (Unpublished report of the
National Marine Fisheries Service, P.O. Drawer 1207,
Pascagoula, MS.)
- Based
on the requirements outlined in the red snapper stock
assessment, a baseline for reduction is established, and
current reduction capabilities are examined. Although the
majority of red snapper taken are age-0, and are not
excluded with any efficiency, the majority of bycatch
mortality (vs. natural mortality) occurs on age-1 fish,
thus the potential for mortality reduction lies in this
less numerous group. The fraction of age-I fish removed
(excluded from the gear) is greater, thus the potential
to increase stock size. Fifty percent reductions in
mortality from the 1982-1986 level of 1.82 are necessary,
and according to the research on bycatch reduction gears,
this reduction in overall F for age-0 and age-I combined
is achieved. The report notes that non-gear options
(closures) would only work if there was an actual
reduction in fishing effort; any closure which simply
moves fishing effort to other red snapper grounds only
transfers or delays mortality.
- Powers,
J.E., C.P. Goodyear, and G.P. Scott. 1987. The potential
effect of shrimp fleet bycatch on fisheries production of
selected fish stocks in the Gulf of Mexico. NMFS
unpublished report, contribution No. CRD-87/88-06 of the
Coastal Resources Division, Miami Lab, 75 Virginia Beach
Dr., Miami, FL 33149.
- According
to this companion report to Nichols et al. (1987),
bycatch reduction has potential for increasing stocks of
fishery-important finfish species such as red snapper,
the mackerels, and red drum. Reduction of red snapper
bycatch has the potential to increase yield by 30-90
percent depending on the level of natural mortality. For
Spanish mackerel, the potential is 40-60 percent, and for
king mackerel, the potential is 20-30 percent. No
specific computations were made for red drum other than
to note bycatch reduction of adults vs. juveniles was
unknown, and other than noting that bycatch reduction
would benefit juvenile recruitment. (NOTE -- the
implementation of TEDs in the late 1980's all but
eliminated the catch of large red drum). This paper
hedges every statement with phrasing such as "given the
variability of the estimate" and "due to uncertainty";
apparently although statistically valid in exercise, the
results should be considered speculative
projections.
- Sheridan,
P.F., J.A. Browder, and J.E. Powers. 1984. Ecological
interactions between penaeid shrimp and bottomfish
assemblages. pp. 235-254 In: J.A. Gulland and B.J.
Rothschild, (eds.). Penaeid shrimps -- their biology and
management. Fishing News Books, Farnham,
England.
- To
assess the effects of better utilization of shrimp trawl
bycatch, two models were used to evaluate the possible
impact on shrimp stocks through reductions in quantity of
discards. Elimination of bottomfish discards back to the
ecosystem would reduce shrimp stock by as much as 25
percent through reduced nutrients available for the
ecosystem and food web. Contrastingly, if bycatch {dead}
discard were reduced through gear modifications that
reduced the catch (bycatch reduction devices), the
resulting shrimp stock reduction would be approximately 8
percent. The report does note that shrimp production is
more likely influenced by environmental changes resulting
in annual fluctuations in production. Any changes in
discard-shrimp interactions would be masked by natural
variation.
- Texas
A&M Sea Grant. 1991. Bycatch - a matter of opinion.
Texas Shores 23(3).
- This
Sea Grant quarterly publication is entirely dedicated to
the bycatch issue. As noted in an introductory article,
it is not a Sea Grant position, but everyone who is
interested will find something in the issue to agree
with, much to disagree about, and a lot to think about.
Articles include information on TEDs to BEDs (bycatch
excluder devices), recreational snapper fishing, snapper
bycatch in trawls, commercial snapper fishing, the
conflicts among various interest and user groups
concerning snapper, and the policy issues and who is
responsible for addressing the issues.
- Thomas,
J.S., G.D. Johnson, and C. Formichella. 1996. Bycatch:
the social dimensions. University of South Alabama,
Mobile, Alabama. (Unpublished at the time of this
report).
- Social
scientists conducted a Gulf-wide survey of shrimpers to
describe their current social conditions, and discuss
perceptions fishermen have about bycatch. Among the more
interesting findings, 39.9 percent of the shrimp
fishermen interviewed felt they make enough money to
support their family under current conditions. This
number was reduced to 5.4 percent if bycatch regulations
were enacted. When asked about various bycatch regulatory
preferences, 15.4 percent of the fishermen preferred
closed areas, 11.3 percent preferred closed seasons, 6.1
percent preferred bycatch reduction devices, and 22.7
percent preferred some form of license limitation. One
serious shortcoming of this study is that no Vietnamese
fishermen were interviewed.
- Ward,
J.M. 1994. The bioeconomic implications of a bycatch
reduction device as a stock conservation management
measure. Marine Resource Economics 9:227-240. (A
manuscript by this author in press with the Southern
Journal of Business and Economics entitled "Static and
dynamic implications of a gear modification designed to
reduce bycatch in a stylized fishery" was also reviewed.
Both documents present similar material.)
- Based
on bioeconomic modeling, bycatch reduction in the shrimp
fishery, especially for species of recreational and
commercial importance, will not necessarily lead to
enhanced fish stocks. All savings accrued from bycatch
reduction will be negated after the fish recruit to the
directed fisheries. With increased recruitment and
availability, catch in the directed fishery will
increase, leading to subsequent increased effort by those
fisheries. This reallocation of stock harvest, if
unregulated, will eventually reduce stock to the
previously existing level. This report notes that only if
catch and effort in the directed fisheries are regulated
can bycatch reduction actually have a beneficial effect
on fish stocks. The extensive list of literature cited in
this report (includes several not listed in this
bibliography) is additionally very good, providing
numerous references to all aspects of bycatch, its
reduction, and the implications of those management
efforts.
- Ward,
J.M. 1994. Stock conservation implications of proposed
bycatch reduction management regulations: social and
economic research panel trawl bycatch session. Gulf of
Mexico Fishery Management Council. NMFS, St. Petersburg,
Florida.
- This
amplification of the above-referenced work makes the
following observations in light of bioeconomic modeling
principles: 1) Gear modifications should reduce finfish
bycatch levels in the shrimp fishery; 2) The increase in
vessel operating costs caused by BRD adoption should
reduce shrimp fishing effort levels and lead to reduced
finfish bycatch levels; 3) The shrimp loss associated
with a particular BRD design induces increased shrimp
fishing effort levels with concomitant increased bycatch
levels; 4) While finfish bycatch levels are reduced,
bycatch reduction devices in and of themselves do not
result in long run increases in finfish stock sizes; 5)
Short run increases in finfish stock size induce
increases in recreational and commercial finfish fishing
effort levels; and 6) Long run equilibrium stock size
returns to its initial equilibrium level with increased
commercial and recreational fishing effort levels,
increased fishing costs and slightly increased harvest
levels.
Non-Gear
Shrimp Trawl Bycatch Reduction Efforts:
-
- Dawson,
C.E. 1957. Preliminary report on the effects of closing
Calibogue Sound, South Carolina, to shrimp trawling.
(Typewritten manuscript - apparently to South
Carolina Wildlife Resources Commission.)
- Closure
of a traditional shrimp and crab trawl area in 1957
allowed for examination of the effects of no trawling on
that area compared to areas which remained open. Catch
rates during the one-year closure were compared to the
mean catch rates of 1953-1956. The report noted that
perhaps the largest variable was the annual fluctuations
of local populations of shrimp and crabs (this type of
fluctuation probably precludes any good comparison of one
year to a four-year average). The author noted that there
were no substantial or significant increases in
productivity for closed vs. open areas.
- Nichols,
S., J. Nance, C.P. Goodyear, A. Shah, and J. Watson.
1995. Some considerations in determining bycatch
reduction requirements. (Unpublished report of the
National Marine Fisheries Service, P.O. Drawer 1207,
Pascagoula, MS.)
- Based
on the requirements outlined in the red snapper stock
assessment, a baseline for reduction is established, and
current reduction capabilities are examined. Although the
majority of red snapper taken are age-0, and are not
excluded with any efficiency, the majority of bycatch
mortality (vs. natural mortality) occurs on age-I fish,
thus the potential for mortality reduction lies in this
less numerous group. The fraction of age-I fish removed
(excluded from the gear) is greater, thus the potential
to increase stock size. Fifty percent reductions in
mortality from the 1982-1986 level of 1.82 are necessary,
and according to the research on bycatch reduction gears,
this reduction in overall F for age-0 and age-I fish
combined is achieved. The report notes that non-gear
options (closures) would work only if there was an actual
reduction in fishing effort; any closure which simply
moves fishing effort to other red snapper grounds only
transfers or delays mortality.
- Whitaker,
J.D., L.B. DeLancey, and J.E. Jenkins. 1989. A study of
the experimental closure of South Carolina's sounds and
bays to commercial trawling. Technical Report 72, Comm.
Crustacean Mgmt. Sect., Off. Fish. Mgmt., Div. Marine
Res., S.C. Wildl. and Mar. Res. Dept.
- During
a two-year study of closed inshore areas, there appeared
to be no effect of long-term (55 years) trawling in the
areas. Catch rates of most finfish (especially those of
recreational and commercial importance) indicated that
the stocks appeared to be in relatively good condition.
The same was true for white shrimp. Catches and relative
abundance of these species compared to areas which had
never been open were not different. The conclusion
reached in this study reflected that of Dawson 1957 -
that stocks of estuarine dependent finfish fluctuate
primarily in response to local and seasonal environmental
conditions.
Turtle
Excluder Devices (TEDs) -Finfish Bycatch
Reduction:
-
- Andrew,
N.L., S.J. Kennelly, and M.K. Broadhurst. 1993. An
application of the Morrison soft TED to the offshore
prawn fishery in New South Wales, Australia. Fisheries
Research 16:101-111.
- Comparisons
of the catch in a net equipped with a Morrison TED to a
net without a TED indicated no significant alteration of
the catch of shrimp, but a reduction in the unwanted
finfish catch. Total biomass was reduced by approximately
32 percent, or 9 kg/90-minute tow. It was noted that the
catch of commercially valuable finfishes was
substantially reduced, and that the income earned by
fishermen was reduced approximately 4
percent.
- Christian
P.A., and D.L. Harrington. 1987. Loggerhead turtle,
finfish, and shrimp retention studies on four turtle
excluder devices (TEDs). pp. 114-127 In:
Proceedings of the non-game and endangered wildlife
symposium, 8-10 Sept., Georgia Dept. Natural Resources,
Social Circle, Georgia.
- Four
TEDs (NMFS collapsible, Georgia, Louisiana, Texas) were
tested for their efficiency. There was 100 percent turtle
exclusion for all TEDs, and total biomass was reduced
from 23-45 percent. The various TEDs had different shrimp
retention rates with only one (Texas TED) having a
statistically significant 23 percent shrimp loss. Fish
exclusions varied by species by TED with the Texas TED
reducing the most and the Georgia TED having the least
reduction.
- Holland,
B.F. Jr. 1989. Evaluation of certified trawl efficiency
devices (TEDs) in North Carolina's nearshore ocean. Final
Report project 2-439-R (funded in part by NOAA, NMFS
Award NA87WCD06100), North Carolina Division Mar. Fish.,
P.O. Box 769, Morehead City, NC 28557
- Four
different TED designs (2 configurations of a Georgia TED,
a Parrish TED, and Morrison TED) were tested for their
efficiency at turtle exclusion, finfish exclusion, and
shrimp retention. For a 4" Georgia TED, total finfish was
reduced about 15 percent while shrimp loss in pounds was
about 3-5 percent. With a 2 5/16" grid, this TED reduced
finfish by 20 percent and lost 5 percent of the shrimp by
weight. The Parrish TED reduced finfish by 75 percent and
lost over 50 percent of the shrimp (the report notes no
reasons were discerned as to why this TED worked as it
did). The Morrison TED reduced finfish and shrimp by
about 25 percent.
- Kendall,
D. 1990. Shrimp retention characteristics of the Morrison
soft TED: a selective webbing exclusion panel inserted in
a shrimp trawl net. Fisheries Research
9:13-21.
- Fishery-independent
surveys, mimicking commercial operations, tested the
Morrison TED for its turtle exclusion and bycatch
reduction capabilities. This report analyzed the latter
of these concepts. Forty-eight tows were made, and using
a minimum shrimp catch of 4.5 kg/hr (as per commercial
fishermen's notes that this was an economic minimum), 27
of the tows were used to compare shrimp catch rates and
bycatch reduction against a net without a TED. There was
no difference in shrimp catch rates when catches exceeded
the minimum threshold; total biomass was reduced by 24
percent. The report noted that the Morrison was not a
preferred TED at the time, but that with proper
(emphasized) installation, it provided optimal results.
Fishers were concerned that it excluded many marketable
fishes.
- Murray,
J.D. 1990. Laboratory and field experimentation of three
TED designs to eliminate shrimp loss. Final report
Saltonstall-Kennedy Grant Program award (S-K NA89WC -H-
SK036). UNC Sea Grant College Program, Raleigh, North
Carolina.
- Flume
tank testing of scale model nets and TEDs as well field
observations of full-scale gear led to the development of
TED modifications to help reduce shrimp loss. Although
the project was targeted at minimizing shrimp loss, a
spin-off publication "Blueprints" from UNC Sea Grant
contains a table depicting the differences in total
biomass between a TED net and a control (net with no TED)
during the tests.
- National
Marine Fisheries Service. 1993. Cruise results: shrimp
trawl bycatch reduction, NOAA Ship Oregon II
Cruise 92-05 (201) 09/04-29/92. NMFS Pascagoula Lab, P.O.
Drawer 1207, Pascagoula, MS 39568.
- Three
excluder devices were tested: a large mesh surrounding a
funnel, a TED with side openings, and a fisheye. The
side-opening TED had a 46 percent finfish reduction and
an 8 percent shrimp loss. A fisheye had an 7 percent
finfish reduction and a 3 percent shrimp gain. The large
mesh design was only tested for water flow and
performance; it was not compared to other catches.
(this is only one of several cruise reports that are
available over time on this topic; contact
NMFS).
- Renaud,
M., G. Gitschlag, E. Klima, A. Shah, J. Nance, C.
Caillouet, Z. Zein-Eldin, D. Koi, and F. Patella. 1990.
Evaluation of the impacts of turtle excluder devices
(TEDs) on shrimp catch rates in the Gulf of Mexico and
South Atlantic, March 1988 through July 1989. NOAA Techn.
Memorandum NMFS-SEFC-254.
- During
3,808 tows, observers onboard commercial shrimp vessels
tested two TED types for efficiency. Overall, a 10
percent shrimp loss was found for quad-rigged vessels,
and a 2 percent loss for twin-rigged vessels; finfish
reduction was about 10-15 percent. For a Georgia TED with
a funnel, finfish catch was 3.9 lb per hour, whereas
without a funnel it was 12 lb per hour. Additional
detailed information is available in this document
comparing efforts in the Gulf and the South Atlantic.
(results from this document led to Renaud et al. 1992;
see below)
- Renaud,
M., G. Gitschlag, E. Klima, A. Shah, D. Koi, and J.
Nance. 1991. Evaluation of the impacts of turtle
excluder devices (TEDs) on shrimp catch rates in the Gulf
of Mexico and South Atlantic, September 1989 through
August 1990. NOAA Techn. Memorandum
NMFS-SEFC-288.
- A
mean shrimp loss of 0.7 lb/hr was documented for Georgia
and Super Shooter TEDs combined. The Georgia TED gained
nominally (0.05 lb/hr) while the Super Shooter lost 0.16
lb/hr; these are minimal differences. Differences in
finfish catch was about 10 lb/hr (210 vs. 200 lb/hr),
although the results were not significantly different.
There was a more substantial loss of shrimp from the pink
shrimp fishery; the brown and white shrimp fishery
efforts which comprise the bulk of the efforts did not
show decreased yield. (results from this document led
to Renaud et al. 1992; see below)
- Renaud,
M., G. Gitschlag, E. Klima, A. Shah, D. Koi, and J.
Nance. 1992. Loss of shrimp by turtle excluder devices
(TEDs) in coastal waters of the United States, North
Carolina to Texas: March 1988 - August 1990. Fish. Bull.
U.S. 91:129-137.
- Three
TEDs were tested aboard commercial vessels during normal
working conditions. These included a Georgia TED with and
without a funnel, and a Super Shooter with a funnel. Both
configurations of the Georgia TED lost statistically
significant amounts of shrimp; with a funnel the loss was
4 percent, without a funnel the loss was 14 percent. The
Super Shooter did not lose statistically significant
amounts of shrimp (-1.4 percent). All TEDs lost more
shrimp in the Florida area, and the Georgia TED with a
funnel also lost shrimp off Louisiana and in all seasons
except winter. Without a funnel, the Georgia TED
consistently lost shrimp in all areas and
seasons.
- Vendetti,
R.A., R.G. Overman, L.G. Parker, and D.L. Harrington.
1996. Improved methods and procedures for the transfer of
technology and the education of constituency groups for
devices that will reduce the bycatch in shrimp trawls.
MARFIN final report (Award NA57FF0051) by the University
of Georgia Marine Extension Service, 715 Bay Street,
Brunswick GA 31523 to the National Marine Fisheries
Service.
- Several
bycatch reduction devices (BRDs) and
turtle-excluder-devices (TEDS) were tested for their
abilities to reduce unwanted bycatch from shrimp trawls.
BRDs tested included expanded mesh, Kiffe BRD, and
fisheyes. Some TEDs were also examined. Tests were
conducted in various South Atlantic Bight areas from
South Carolina to northeast Florida, and finfish and
biomass reductions with the various BRDs were substantial
(20-40 percent). Shrimp losses were minimal and not
usually significantly different. Only limited numbers of
a key species, weakfish, were collected, thus reduction
rates (which were not great) may have been more
influenced by the scarcity of the species than the gear's
ability to exclude them. Each set of tests is reported
independently, thus it is hard to present general
quantitative results of this study.
- Watson,
J.W., and C.W. Taylor. 1990. Research on selective shrimp
trawl design for penaeid shrimp in the United States; a
review of selective shrimp trawl research in the United
States since 1973. Proceedings of the Fisheries
Conservation Engineering Workshop, Narragansett, RI,
April 4-5 1990. (also available through
NMFS Lab, P.O. Drawer 1207, Pascagoula, MS
39568).
- This
is a good summary document of the bycatch research that
has occurred over time. In the early 1970's, separator
panels, used elsewhere, were tested in the shrimp fishery
with little success because many of the small fishes were
gilled in the apparatus. Shrimp losses were high as well
and tests on this design were discontinued. Electrical
stimulators were shown to be effective, but the high cost
was prohibitive. Developments of the NMFS TED, and
subsequent research, led to separation rates of as high
as 78 percent in the daytime and 50 percent at night.
Other TEDs developed later did not have the same
capabilities, but research was continuing on ways to
improve their efficiency.
- Watson,
J.W. 1980, 1981. Sea turtle excluder trawl project;
milestone reports. NMFS, Pascagoula, P.O. Drawer 1207,
Pascagoula, MS. 39568.
- These
two reports outline the research during 1978 through
1980. Starting with front end deflectors which worked
poorly, NMFS developed TEDs in the bags. Focused on the
turtle excluding capabilities, these reports also note
shrimp loss with the TEDs; in most cases shrimp loss was
negligible. Finfish reductions are not
reported.
- Watson,
J.W. 1981, 1983, 1983, 1984. Sea turtle excluder trawl
development, annual reports (FY81, FY82, FY83, FY84).
NMFS, Pascagoula, P.O. Drawer 1207, Pascagoula, MS.
39568.
- These
reports outline research during each of the fiscal years,
noting the progress towards developing efficient TEDs
(NMFS design). For the major shrimp grounds, the TED nets
caught nominally more shrimp than the non-TED nets. The
1981 report notes little bycatch reduction; either for
total biomass or finfish. The FY82 results indicated an
approximate 10 percent increase in shrimp catch for the
TED nets, and even with modifications for a finfish
deflector, little finfish were excluded. For FY83,
emphasis was on making the TED smaller and lighter with
different construction and material. With additional
modifications, finfish reduction was over 50 percent for
daytime towing and 10 percent for nighttime; several
other modifications such as hummerwires were also
examined and show potential. For FY84, further
modifications were made to make the TED lighter and less
bulky, and to increase finfish reduction after dark,
cyalume light sticks were attached to the deflectors;
this produced about 50 percent reductions in finfish with
nighttime towing.
- Watson,
J.W., J.F. Mitchell, and A.K. Shah. 1986. Trawling
efficiency device: a new concept for selective shrimp
trawling gear. Fisheries 48(1):1-9.
- Trawl-efficiency-devices
(TEDs) {which later became turtle-excluder-devices} were
tested through both fishery-independent and
fishery-dependent sampling on the commercial shrimp
grounds. Three TED designs were tested: two collapsible
hard TEDs, and a rigid frame TED. The TED itself serves
as a mechanical separator for large organisms; the
primary target being turtles, but including large fishes
such as red drum, sharks, etc. Several variations of
designs with additional flaps or leading panels were
tested to further evaluate finfish exclusion with these
gears. The collapsible steel TED lost a non-significant 2
percent of the shrimp and 51 percent of the finfish, with
common species such as Atlantic croaker, spot, butterfish
and bumper being excluded at 50-70 percent. A solid
fiberglass TED lost a non-significant 5 percent of the
shrimp and 53 percent of the finfish, again with common
fishes being excluded at rates as high as 70-80 percent.
The collapsible version of the fiberglass TED had a
nominal shrimp gain, and lost 52 percent of the finfish,
with common species being excluded at rates better than
60 percent. Comparative commercial efforts had 1 percent
shrimp losses and 30-55 percent finfish
losses.
- Wenner,
C.A. 1987. Results of tests conducted on two different
trawl efficiency devices (TED) in South Carolina coastal
waters. A final report (to whom unknown). Marine Research
Institute, S. Carolina Wildl. and Marine Resources Dept.
P.O. Box 12559, Charleston, SC 29412.
- Several
TED tests were conducted during this study. Using 48-foot
nets in St. Helena Sound, during four tows, fishes were
reduced by about 66 percent, blue crab by 75 percent,
without any loss of shrimp using a NMFS TED. In a
follow-up study to these preliminary estimates, during
less than 60 tows in brown shrimp, the NMFS TED and the
Georgia TED were compared against a non-TED net, and
against each other. Against a non-TED net, the NMFS TED
lost approximately 5 percent of the brown shrimp, and the
Georgia TED lost about 16 percent. Although this was
quite different, when the two TEDs were tested against
each other, the Georgia TED only had about 3 percent less
shrimp than the NMFS TED net. Against a non-TED net, the
NMFS TED reduced finfish by 55 percent by weight, and the
Georgia TED 37 percent. Against each other, the NMFS TED
lost 30 percent more fish than the Georgia TED. During 10
tows in the white shrimp season, the NMFS TED caught
about 3 percent less shrimp than the non-TED net, and the
Georgia TED caught 30 percent less by weight. Against
each other, the Georgia TED had 15 percent less white
shrimp by weight than the NMFS TED. Finfish were reduced
during the white shrimp sampling by 53 percent using the
NMFS TED, and by 57 percent with the Georgia TED. This
last number was biased in that the net was not rigged
with chafing gear, and the dominant species (star drum)
could exit through the webbing of the bag. The authors
note this was the primary difference in the finfish catch
during the Georgia TED tests.
Shrimp
Trawl Bycatch Reduction Devices (BRDs):
-
- Bahen,
J.J., J.D. Murray, and R.A. Rulifson. 1993. Development
and evaluation of finfish separator device and TED
combination to reduce bycatch in the shrimp fishery.
Final Report, NMFS Award NA17FD0101, by Univ. North
Carolina Sea Grant Program, Box 8605, North Carolina
State University, Raleigh, NC 27695.
- A
large mesh panel located over a funnel and diamond
cut-outs (snake-eyes) over a funnel were tested. These
were first examined for their effect on net integrity;
after that, field testing monitored the gear efficiency.
The diamond mesh BRD reduced fish by 51 percent without a
shrimp loss in one trial and by 38 percent in another
trial but shrimp loss was 7 percent. In a third test,
fish were reduced by 37 percent; no shrimp values are
given. The square mesh BRD reduced finfish by 70 percent,
but shrimp catches were too low to be
representative.
- Christian,
P.A., D.L. Harrington, D.R. Amos, R.G. Overman, L.G.
Parker, and J.B. Rivers. 1993. The reduction of finfish
capture in South Atlantic shrimp trawls. Final report of
a NOAA/NMFS Saltonstall-Kennedy Award (NA27FD0070) to
University of Georgia Marine Extension Service, 715 Bay
Street, Brunswick, Georgia 31523.
- During
the study a low profile trawl, three configurations of
fisheyes, and three colors of expanded mesh BRDs were
tested. The low profile trawl did not show any
substantial finfish reductions, although there was good
reduction of some species at night, especially those that
are more pelagic such as mackerels. For the various BRDs
tested, the authors note that an improper TED angle in
the "control" net probably allowed for greater exclusion
by the TED in that net, thus the values generated here
for the "experimental" nets are suspect.
- Coale,
J.S., R.A. Rulifson, J.D. Murray, and R. Hines. 1994.
Comparisons of shrimp catch and bycatch between a skimmer
trawl and an otter trawl in the North Carolina inshore
shrimp fishery. N. Amer. J. Fish. Management
14:751-768.
- Brown
and pink shrimp catches were better in an otter trawl; in
part because of gear problems with the initial skimmer
design and because it could not fish in deep water. When
the two gears were fished in similar depths the catch
rates were more comparable. For white shrimp, the skimmer
caught six times more by weight than the otter trawl. The
skimmer caught 0.47 kg/min bycatch vs. 0.66 kg/min for
the otter trawl. During the brown shrimp efforts skimmer
fish to shrimp ratios were 7:1 vs. 8.4:1 for the otter
trawl (under differing sampling as noted). During the
white shrimp season, the fish to shrimp ratio was 1.4:1
vs. 12.5:1 for the otter trawl. Twelve of 16 finfish
species observed for survivability showed increased
survival with the skimmer trawl because of shorter
fishing times and handling practices on deck. The skimmer
does take a larger percentage of pelagic fishes such as
menhaden, bluefish, and mackerels because it fishes the
entire water column. (More detailed information
available in Coale, J.S. 1992. Changes in bycatch using a
skimmer trawl in the North Carolina shrimp fishery. MS
Thesis, Dept. of Biology, East Carolina University,
Greenville, NC 27858.)
- Gulf
and South Atlantic Fisheries Development Foundation.
1994. Organization and management of a Gulf of Mexico and
South Atlantic Ocean fishery bycatch management program
(Year II). Saltonstall-Kennedy Grant Program, final
report to the National Marine Fisheries Service (Award
NA37FD0032) by the Foundation (Ste. 997, 5401 W. Kennedy,
Tampa, FL 33609).
- As
part of this grant, observers logged 744 days on 63
commercial fishing trips gathering bycatch data for
characterization of the catch and evaluating various BRDs
under actual operating conditions. A total of 362 nets
were sampled for characterization, and 653 tows compared
the catch of a "control" (without a BRD) net to the catch
of a BRD-equipped net. The report notes that finfish
comprised 67 percent of the catch by weight, while shrimp
represented 19 percent. Two BRDs were extensively tested
in the Gulf of Mexico: a fisheye placed in the top-center
of the bag, 45 meshes back from the start of the bag,
reduced total biomass by about one-third, excluded 20
percent of the red snapper, and had a minimal shrimp
loss; the extended funnel-expanded mesh BRD excluded more
than 25 percent of the red snapper with no shrimp loss,
but overall total biomass reduction was limited. In the
South Atlantic, the fisheye was tested in two top center
positions (30 meshes and 45 meshes from the start of the
bag). Results were similar to those obtained in the Gulf
of Mexico. Weakfish reductions were good (70 percent) in
summer, but declined to 20 percent in the fall. Shrimp
loss during brown shrimp season was about 6-7 percent,
but declined to nearly zero loss during white shrimp
season. Minimal testing in south Florida during pink
shrimp season indicated a 7 percent shrimp loss with
about 40 percent finfish reduction for a
fisheye.
- Gulf
and South Atlantic Fisheries Development Foundation.
1995a. Continued implementation of high priority
objectives outlined in a Gulf of Mexico and South
Atlantic fishery bycatch research program. MARFIN Grant
Program final report to the National Marine Fisheries
Service (Award NA47FF0007) by the Foundation (Ste. 997,
5401 W. Kennedy, Tampa, FL 33609).
- This
report updated the foundation's efforts (see Gulf and
South Atlantic Fisheries Development Foundation 1994) to
characterize the shrimp trawl fishery catch and to
evaluate various BRDs. During 304 tows comparing the
catch of a net with a BRD to the catch of a net without a
BRD, several various configurations of fisheye shapes and
placements were tested; other gears tested included
snake-eyes (diamond holes in the net outside a funnel),
and versions of expanded mesh. Small fisheyes (ca. 4"
high by 7" wide) showed little fish reduction; a medium
sized fisheye (5" x 12") at 30 meshes from the front of
the bag showed a 23 percent reduction in total biomass, a
4 percent shrimp loss and fish were excluded at various
rates; red snapper were reduced by 47 percent by weight.
Initial tests of a modified expanded mesh-extended funnel
BRD (two additional bars of expanded mesh) indicated a 14
percent total biomass reduction, a 1 percent shrimp loss,
and 20-80 percent reductions in finfish. A side-shooting
TED had a 15 percent reduction in total biomass, a 3
percent shrimp loss, a 6 percent reduction in red
snapper, and 20-75 percent finfish reductions depending
on species. The report also summarizes the evaluations of
fisheyes and expanded mesh (all configurations combined)
over the entire study period. For fisheyes (a total of
341 tows), shrimp loss was 1 percent, red snapper
reduction was 27 percent, and total finfish reduction was
33 percent; for expanded mesh (a total of 162 tows),
there was no shrimp loss, a 26 percent reduction in red
snapper and a 23 percent reduction in total
finfish.
- Gulf
and South Atlantic Fisheries Development Foundation.
1995b. Continued observer coverage of the Gulf of Mexico
and South Atlantic shrimp fisheries to characterize the
catch and evaluate the efficiency of bycatch reduction
devices. Final report to the National Marine Fisheries of
a special unallied authorization award (NA47FM0131) by
the Foundation (Ste. 997, 5401 W. Kennedy, Tampa, FL
33609).
- This
report furthers the work completed by the Foundation (see
1994 and 1995a) under the bycatch program. During the
study, 1,010 tows compared the efficiency of various BRDs
which contributed to a total Foundation database of 1,441
tows in the Gulf of Mexico and 542 tows in the South
Atlantic. Using the entire database, fisheyes (seven
configurations) were determined to exclude finfish by
15-30 percent with less than a 4 percent shrimp loss; red
snapper were excluded at 25-40 percent and weakfish by
10-30 percent. Expanded mesh-extended funnel (two
configurations) had a 20-25 percent finfish reduction
without a shrimp loss; red snapper were reduced by 25
percent and weakfish by 20 percent. Preliminary results
on several tests comparing a "naked" net (without a TED)
to a TED-net indicated that some TEDs exclude fish well,
especially soft TEDs.
- Hines,
B., S. Coale, R. Rulifson, and J. Murray. 1993. The
skimmer trawl in North Carolina estuaries. Univ. North
Carolina Sea Grant College Program, publication
UNC-SG-93-01 (funded by NOAA/NMFS Saltonstall Kennedy
grant program NA90AADSG062).
- This
booklet was developed to convey information concerning
the skimmer trawl to the general public and the fishing
community. Catches in skimmers were compared to otter
trawls, and for white shrimp the skimmer trawl was more
efficient. For brown shrimp, the skimmer could not be
deployed in deep enough water; catches were 6 percent of
the total catch vs. 17 percent for otter trawls. Bycatch
was compared between gears as well; fish to shrimp ratio
was 1:1 vs. 8:1 for the otter trawl. Skimmer trawl
bycatch was more likely to survive because of the way the
gear is fished and the catch is handled. The booklet also
tells how to build a skimmer and outlines fishing
techniques. (The scientific results are better
described in Coale
et al. 1994.)
- McKenna,
S.A., and J.P. Monoghan Jr. 1991. Gear development to
improve management of commercial fisheries in North
Carolina. Saltonstall-Kennedy grant program (award
NA90AAHSK052) annual contract report to the Gulf and
South Atlantic Fisheries Development Foundation (contract
43-01), Suite 997, Lincoln Center, 5401 W. Kennedy,
Tampa, FL 33609.
- Three
bycatch reduction device (BRD) designs were examined in
the North Carolina trawl and flynet fishery. These
included fisheyes, accelerator funnels, and large mesh in
the tailbag. The fisheyes reduced finfish catch by 50-60
percent with minimal shrimp losses. Larger mesh (1" bar)
vs. smaller mesh (3/4" bar) did not reduce fish in the
trawls, but 1-3/8" bar allowed many smaller fishes out
vs. 1" bar in the flynet fishery. Four TEDs were also
tested and showed that total finfish catch varied from
+35 to -35 percent and shrimp catches varied from +17
percent to -4 percent compared to a net with no
TED.
- Murray,
J.D., S.L. Diamond, and J.J. Bahan. 1994. A program to
distribute and evaluate bycatch reduction devices in
inshore waters of North Carolina. MARFIN final report
(Award NA37FF038) by the University of North Carolina Sea
Grant Program to the National Marine Fisheries Service.
North Carolina State University, P.O. Box 8605. Raleigh,
North Carolina 27695.
- Following
a series of industry-oriented workshops to introduce
various bycatch reduction devices (BRDs) to the shrimp
industry, four BRD types were distributed to 25 fishermen
for their use and evaluation during the 1993 fishing
season. These were accompanied by questionnaires which
were to be filled out before and after the season. Most
fishermen had long-term experience, fished on vessels
larger than 35 feet, trawled an average of 130 days per
year, and preferred the fisheye type BRDs. The fishermen
noted that the device lost shrimp and reduced bycatch by
less than 10 percent; however they would use the BRDs
during the next shrimping season. To compare the results,
four shrimpers were contracted to conduct BRD evaluations
with onboard observers with data collection following the
Bycatch Program protocols. The results of this study
confirmed the initial evaluations by fishers. The report
notes that 91 percent of the fishers reported they would
use BRDs without regulations in order to address the
conservation concept of bycatch reduction.
- Murray,
J.D., J.L. Gearhardt, R.A. Rulifson, and C.W. Wescott.
1995. Introduction of larger mesh webbing in the belly
and wings of traditional shrimp trawls to reduce bycatch
in inshore waters. Final report, Saltonstall-Kennedy
grant NA37FD0088 by Univ. North Carolina Sea Grant
Program, Box 8605, North Carolina State University,
Raleigh, NC 27695.
- Given
previous research on large mesh work (see several other
citations in this section), large sections of large mesh
were installed in a trawl to allow fish to escape. Shrimp
loss using this design was substantial, and deemed
unacceptable for application to the fishery. However,
blue crab escapement was substantial as well as catches
of summer flounder. Thus, this design may be applicable
for these fisheries, allowing escapement of undersized
animals.
- National
Marine Fisheries Service. 1995. Cooperative research
program addressing finfish bycatch in the Gulf of Mexico
and South Atlantic shrimp fisheries: a report to
Congress, April 1995. USDOC, NOAA, NMFS. National Marine
Fisheries Service, 9721 Executive Center Drive, St.
Petersburg, FL 33702.
- The
document outlines the goals, objectives, and results to
date for a federally mandated bycatch reduction research
program. Eight program objectives are discussed in detail
- characterization, improved stock assessments,
evaluation of bycatch reduction devices (BRDs), non-gear
options, management options, information and education
programs, identification of other mortality, and
development of a centralized database. This booklet
provides a good overview of the program and the status of
the research. A substantial database including nearly
4,000 commercial shrimp trawl tows has been accumulated.
Substantial advances have been made in characterizing the
catch through a large-scale fishery-dependent survey.
Results of two types of bycatch reduction devices (BRDs)
are summarized: fisheyes and expanded mesh-extended
funnel. Fisheyes were reported to exclude 33 percent of
the fish, 27 percent of the red snapper, and lose 1
percent of the shrimp. Expanded mesh reduced 23 percent
of the fish, 26 percent of the red snapper, and had no
shrimp loss. No South Atlantic testing evaluations are
reported in this document.
- Pearce,
K.B., D.W. Moye, and S.K. Strasser. 1989. Evaluation of
trawl excluder devices in the Pamlico Sound shrimp
fishery. Report 88-07 North Carolina Dept. Natural
Resources and Comm. Development, Division of Marine
Fisheries, Morehead City, NC 28557.
- Four
BRDs were tested in Pamlico Sound: 1) Scottish separator
trawl {SST}; 2) bottom- positioned fisheye; 3) Georgia
TED; and 4) Parrish TED. The SST separated fish but lost
shrimp, the Georgia TED and the fisheye reduced fish
without any substantial shrimp loss, and the Parrish TED
lost both fish and shrimp. None but the SST reduced the
catch of weakfish.
- Rogers,
D., B.D. Rogers, J.A. de Silva, and V.L. Wright. 1994.
Evaluation of shrimp trawls designed to reduce bycatch in
inshore waters of Louisiana. Final report MARFIN award
NA17FF0375 to NMFS by School of Forestry, Wildl. &
Fish., LSU, Baton Rouge, LA 70803.
- Industry-developed
bycatch reduction devices were tested in inshore and
nearshore waters of Louisiana. These tests were made with
experimental nets compared to "naked" (without TEDs)
nets. Over the study period, two configurations of two
different BRDs were tested; later in the study expanded
mesh configurations, as developed by NMFS, were also
tested. The four industry BRDs and the NMFS modifications
to the expanded mesh all had good finfish reduction but
lost unacceptable amounts of shrimp (15-25
percent).
- Rulifson,
R.A., J.D. Murray, and J.J. Bahen. 1992. Finfish catch
reduction in South Atlantic shrimp trawls using three
designs of by-catch reduction devices. Fisheries
17(1):9-19.
- Three
BRDs, all working with large mesh escape openings in the
bag (modified Parrish TED, expanded mesh on top of the
bag over a funnel, and square-mesh "snake-eyes" around a
funnel) were tested. None of the BRDs demonstrated a
change in large fish weight compared to the control net.
A major drawback to this paper is that it contains
numerous statements such as "significant
difference...compared to its control...(df =4, F =3.02,
P=0.0367)," but no values are ever given in the text for
the reader to understand what the catch was, only that it
was significantly different. Additional problems included
modifications to the BRDs during the survey, which meant
that five BRDs were tested, not just three, and
comparisons between unmodified and modified gears are
reported. The text mentions problems with sampling design
where port and starboard nets may not have been
calibrated.
- Vendetti,
R.A., R.G. Overman, L.G. Parker, and D.L. Harrington.
1996. Improved methods and procedures for the transfer of
technology and the education of constituency groups for
devices that will reduce the bycatch in shrimp trawls.
MARFIN final report (Award NA57FF0051) by the University
of Georgia Marine Extension Service, 715 Bay Street,
Brunswick GA 31523 to the National Marine Fisheries
Service.
- Several
bycatch reduction devices (BRDs) and
turtle-excluder-devices (TEDs) were tested for their
abilities to reduce unwanted bycatch from shrimp trawls.
BRDs tested included expanded mesh, Kiffe BRD, and
fisheyes. Tests were conducted in various South Atlantic
Bight areas from South Carolina to northeastern Florida,
and finfish and total biomass reductions with the various
BRDs were substantial (20-40 percent). Shrimp losses were
minimal and not usually significantly different. Only
limited numbers of a key species, weakfish, were
collected, thus reduction rates (which were not great)
may have been more influenced by the scarcity of the
species than the gear's ability to exclude them. Each set
of tests is reported independently, thus it is hard to
present general quantitative results of this
study.
- Watson,
J.W., and C.W. Taylor. 1986. Research on selective shrimp
trawl designs for penaeid shrimp in the United States: A
review of selective shrimp trawl research in the United
States since 1973. Food and Agriculture Organization of
the United Nations, Rome, Italy.
-
- This
historical review chronicles some of the early work done
in efforts to separate finfish bycatch from shrimp trawls
using webbing panels, electric trawls, webbing skylights,
and early TEDs. The authors point out that many of the
early attempts at finfish separation were abandoned due
to unacceptable shrimp loss or prohibitive gear costs. At
the time this document was written, the NMFS TED appeared
to be the best option available with the authors noting
"reduced finfish catches by as much as 85 percent during
daytime fishing and 54 percent during nighttime fishing
with no significant difference in shrimp catch rates"
when comparing a TED-equipped net against a control
net.
- Watson,
J.W. 1989. Fish behavior and trawl design: potential for
selective trawl development. pp. 25-29 In:
Campbell, C.M. (ed.). Proceedings of the World Symposium
on Fishing Gear and Fishing Vessels. Marine Institute,
St. Johns, Newfoundland, Canada.
- The
National Marine Fisheries Service began researching the
feasibility of separator trawls for the penaeid shrimp
fishery of the southeast U.S. in the 1960's. Separator
panels, used elsewhere, provided limited success; the
small size of the fishes led to gilling in the web
panels. Examining fish behavior during TED tests resulted
in several concepts that were proposed for further
testing. Fishes, in general, orient to flow in a trawl,
and swim parallel to moving backgrounds (optomotor
response); this may be cued from both visual and lateral
line reception. Modified TEDs with webbing panels that
led fish to escape openings worked well; fish reductions
were 85 percent in daytime and 54 percent at
night.
- Watson,
J., I. Workman, D. Foster, C. Taylor, A. Shah, J.
Barbour, and D. Hataway. 1993. Status report on the
potential of gear modifications to reduce finfish bycatch
in shrimp trawls in the southeastern United States.
1990-1992. NOAA Techn. Mem. NMFS SEFC 327.
- During
1990-1992, NMFS gear specialists tested 51 BRD conceptual
designs for efficiency and functionability. Designs
included gears developed by industry, NMFS, and other
researchers. The report summarizes the designs for 39
BRDs, and the reduction capabilities of 30 prototypes
tested on commercial fishing grounds. Of these, 12 had
finfish reductions of 40-60 percent, and seven had shrimp
retention rates of 90+ percent. BRD designs of expanded
mesh, expanded mesh-extended funnel, HSB (a modified TED
with fish exclusion holes in the side), and fisheyes all
showed promise for more detailed testing. As much as 30+
percent of the dominant fish species were excluded by all
these designs. Good detailed drawings and descriptions of
the various BRDs tested are included in the back of this
document.
- Workman,
I.K., J.W. Watson, and C.W. Taylor. 1992. Trawl gear
modifications to reduce bycatch in the southeastern
United States shrimp fishery (draft manuscript). NMFS,
P.O. Drawer 1207, Pascagoula, MS 39568.
- Beginning
in 1990, NMFS began looking at bycatch excluder devices.
The most promising designs tested included fisheyes, an
expanded mesh around a funnel, and side openings
incorporated behind a TED. A fisheye located on the top
reduced fish by 68 percent but lost 17 percent of the
shrimp. Double fisheyes on the side reduced fish by 56
percent with no shrimp loss. The extended funnel excluded
46 percent of the fish with no shrimp loss, and the side
openings behind a TED reduced fish by 43
percent.
- Workman,
I., J. Watson, D. Foster, C. Taylor, A. Shah, C. Taylor,
and J. Barbour. 1994. Status report on the potential of
gear modifications to reduce finfish bycatch in shrimp
trawls in the southeastern United States. 1993 annual
report by the NMFS Pascagoula Lab, P.O. Drawer 1207,
Pascagoula, MS. 39568.
- This
report updates Watson et al. 1993 and reports on
evaluations of 25 BRD designs. Of these, four (three of
which were modified TEDs) showed good fish reduction
(>40 percent) without significant shrimp loss. Good
detailed drawings and descriptions of the various BRDs
tested are included in the back of this document; this is
an essential part of the document to avoid future
researchers from "reinventing the wheel."
TRAP
FISHERIES
Fish
Traps:
Fish
traps have been in existence for many years, and their use
has increased recently, especially in the eastern Gulf of
Mexico. Few comprehensive studies on this method of fishing
exist. Studies available indicate that much of the bycatch
in this fishery is released alive, thus the impact on the
faunal community is not substantial. However, other logistic
problems with this fishery, including lost traps and
enforcement problems, led the Gulf of Mexico Fishery
Management Council to recently approve discontinuing this
fishery over the next 10 years (approved at the
July 1996 Gulf Council meeting).
-
- Harper,
D.E., J.A. Bohnsack, and D.B. McClellan. 1994.
Investigations of bycatch from the wire fish-trap fishery
in federal waters of southern Florida. Proc. 43rd annual
Gulf Caribb. Fish. Inst.:3-25.
- Observations
from 417 commercially fished wire fish traps in 1990
documented the catch and bycatch from these efforts. In
199 completely sampled traps, 84 percent of the total
weight and 66 percent of the individuals were landed. A
total of 1,884 live fishes were released, and at least 79
percent of these swam down immediately; the fate of the
rest was not documented, thus survival could have been
higher. In addition, 1,080 crustaceans and 15 mollusks
were released; 68 percent of this catch was spiny lobster
released during the closed season for this fishery (most
were noted as legal and no egg-bearing females were
seen). Discard mortality was recorded for 101 fish.
Sublegal fish releases included 144 snapper and grouper
(14 percent by number of all captured fishes for which
size limits exist).
- National
Marine Fisheries Service. 1995. Characterization of the
reef fish fishery of the eastern Gulf of Mexico. A report
to the Gulf of Mexico Fishery Management Council, Reef
Fish Management Committee. Prepared by the Galveston and
Miami NMFS Laboratories. Available through Gulf of Mexico
Fishery Management Council, Ste. 331, 5401 W. Kennedy,
Tampa, FL 33609.
- Observers
aboard commercial fish trap and bottom longline vessels
off Florida documented the catch and bycatch of the
fisheries. For the fish trap fishery, observers aboard 12
trips on six vessels monitored 517 sets totaling 10,654
traps; 36 percent of the traps (3,867) were processed by
the observers. A total of 15,148 fish of 63 taxa were
documented. Approximately 55 percent of the individuals
were released alive, 35 percent were kept, 7 percent were
retained for bait, and 2 percent were released dead or
with an unknown fate. Seven species comprised 88 percent
of the 8,400 fish released, and the majority were red
grouper. Although red grouper is the primary target fish,
more lane snapper were caught, and they accounted for 34
percent of the fishes kept, followed by red grouper at 22
percent. Of the 242 dead discards, 45 percent were red
grouper. 75 percent of the red grouper were undersized
(< 20"). These data were compared to previous fish
trap studies in Florida, where from 50-80 percent of the
bycatch was released, and 2-20 percent was dead. The
observer data were compared to logbook data representing
a total of 1,168 fish trap trips. Five species comprised
78 percent of the total landings, led by red grouper at
43 percent.
- Sutherland,
D.L., and D.E. Harper. 1983. The wire fish trap fishery
of Dade and Broward counties, Florida. FL Mar. Res. Inst.
Publ. 40.
- During
45 commercial trips, 538 traps were hauled and sampled. A
total of 5,984 fish were caught; 62 percent by number and
77 percent by weight were target species. Snapper and
grouper species dominated; the 10 most abundant target
species comprised 51 percent of the total catch and the
10 most abundant non-target species comprised 13 percent.
A total of 478 fish died in the traps. Approximately 20
percent of the traps are lost annually, but other work
suggests that about 50 percent of the fish can escape by
14 days; at that point ingress equals egress.
- Taylor,
R.G., and R.H. McMichael, Jr. 1983. The wire fish-trap
fisheries in Monroe and Collier counties, Florida. FL
Mar. Res. Inst. Publ. 39.
- Over
a one-year period, 1,694 trap hauls caught 10,226 fishes
in Monroe County (MC) and 270 trap hauls in Collier
County (CC) produced 3,111 fishes. Target species
constituted 51 percent of the catch in MC and 70 percent
of the weight; in CC the targets comprised 30 percent of
the catch by number and 70 percent by weight. Five
species comprised 44 percent of the catch by number;
serranids comprised 50 percent of the weight and 15
percent of the number of fishes taken. Four percent of
the fish were dead or injured. Of 619 released fish, 53
percent swam down within one minute; 20 percent died, and
27 percent had done neither at the end of one
minute.
Crab
Trap Fisheries:
Crab
and lobster trap fishing in the Gulf of Mexico is common,
with strong recreational and commercial components. As with
fish traps, regular monitoring of the traps produces a live
release for the majority of the bycatch, including sublegal
target species. The major concern is lost traps that
continue to "ghost" fish. Recent studies have been
completed, and some controls have been implemented,
concerning escape vents and biodegradable materials. These
measures allow the escape of sublegal target species and
non-targeted species, and disable the gear from continuing
to trap organisms after an extended period in the water.
Comprehensive studies are available concerning these issues
in both fisheries.
-
- Arcement,
G., and V. Guillory. 1993. Ghost fishing in vented and
unvented blue crab traps. Proc. La. Acad. Sci.
56:1-17.
- Mortality
in unvented traps was approximately three times higher
than in vented traps due to the higher number of sublegal
crabs.
- Bishop,
J.M. 1983. Incidental capture of diamondback terrapin by
crab pots. Estuaries 6(4):426-430.
- During
tests on pre-molt blue crabs in South Carolina,
diamondback terrapin captures in crab traps were
documented. Males outnumbered females by greater than
2:1, perhaps because large females could not enter the
traps. Most (over 80 percent) were captured in April and
May in a wide range of salinities and temperatures. Based
on the catch rates, and the estimated number of pots
fished in South Carolina waters, along with the estimated
624,000 pots being fished in the U.S. at the time, the
author estimates that blue crab traps may account for the
majority of adult terrapin mortality.
- Eldridge,
P.J., V.G. Burrell Jr., and G. Steele. 1979. Development
of a self-culling blue crab pot. Mar. Fish. Rev.
41:21-27.
- In
tests in South Carolina, crab pots with two escape ports
of 2.5" diameters in the top chamber and one in the
bottom chamber reduced the catch of sublegal crabs by 82
percent. Use of these vents was recommended as a
management measure in blue crab fisheries.
- Guillory,
V. 1989. An evaluation of different escape vents in blue
crab traps. Proc. La. Acad. Sci.
52:29-34.
- Square
and circular escape vents were tested in Louisiana
estuarine crab traps. Both shapes worked equally well (80
percent reduction of sublegals), but square vents were
noted as easier to construct and install.
- Guillory,
V. 1990. Effects of escape vents on catch rates of
pre-molt blue crabs (Callinectes sapidus). Proc.
La. Acad. Sci. 53:20-28.
- Premolt
crabs (peelers) were reduced in vented traps by
approximately 80 percent; similar to sublegal
reductions.
- Guillory,
V. 1993. Ghost fishing by blue crab traps. N. Amer. J.
Fish. Mgmt. 13:459-466.
- 25
traps were baited and after three days, all 307 crabs in
the traps were examined and tagged. An average of 13
crabs were caught per trap, and an additional 35 crabs
recruited to the traps over a year period (with no bait).
Approximately 55 percent of the crabs died. Mortality was
highest during the first month of ghost fishing. Smaller
crabs escaped more effectively from the entrances. Fish
bycatch in the traps included 190 individuals of 11
species; sheepshead were 74 percent of the total followed
distantly by spot, southern flounder and Atlantic
spadefish each at 5 percent.
- Guillory,
V., and J. Merrell. 1993. An evaluation of escape rings
in blue crab traps. Louisiana Dept. Wildl. and Fish.
Techn. Bull. 44. P.O. Box 189, Bourg, Louisiana
70343.
- Escape
ring size and location were evaluated in Louisiana
estuaries. Sublegal crab reductions increased with number
of rings. Three rings of a minimum of 6.03 cm in diameter
were recommended; this produced reductions of 75-80
percent.
- Guillory,
V., and S. Hein. 1995. A review and evaluation of escape
vents in blue crab traps. A manuscript report to
Louisiana Department of Wildlife and Fisheries, P.O. Box
189, Bourg, Louisiana 70343.
- To
reduce undersized catches, requirements for escape rings
have been incorporated into numerous management
strategies. Based on results of the study, three 2-3/8"
diameter rings located on vertical outside walls of the
upper chamber were recommended. Benefits of the rings
include: 1) a reduction of 75-80 percent of undersized
catch; because of differences in the shape of the
carapace, small legal female crabs will have higher
escapement rates too; 2) delayed increase in catch of
legal crabs due to decreased handling mortality on
sub-legal crabs; 3) decreased injury and stress to
sublegal crabs; 4) reduction of ghost fishing; 5) reduced
culling time; 6) enforcement reduction in effort; and 7)
reduction in sale of small crabs. Disadvantages are the
loss of small legal females, and loss of peeler crabs.
This paper also has a good review of other related
studies; many of which are summarized below or in this
document.
-
- Casey,
J.F., S. Doctor, and A.E. Wesche. 1992. Manuscript
on file at Maryland Dept. Nat. Resources, Tawes St.
Office Bldg, Annapolis, MD 21401. Different sizes and
placements of vents provided for sublegal reductions
of as much as 50-90 percent
- Virginia
Marine Resources Commission. 1994a, 1994b.
Manuscripts on file at Va. Marine Resources
Commission, P.O. Box 756, Newport News, VA 23607. In
unvented traps, 34 percent of the small crabs could
escape, while in vented traps 50 percent of sublegal
crabs escaped. Based on measurements and sexes of
crabs collected from commercial gear, approximately
half the immature females, over one-third of the
sub-legal males, and 18 percent of the legal mature
females could escape through a 5.87 cm vent. Reduction
of legal female escapement was accomplished with a
vent of only 5.56 cm.
- Whitaker,
D.K. 1978. Data report for escape ring study.
Manuscript on file at S. Carolina Wildl. and Mar.
Resources Dept., P.O. Box 12559, Charleston, SC 29412.
Two sized rings (6.03 and 6.35 cm) were tested in
South Carolina; sublegal catch was reduced by 75 and
83 percent respectively.
- Whitaker,
D.K. 1980. Escape ring project - summer 1979.
Manuscript on file at S. Carolina Wildl. and Mar.
Resources Dept., P.O. Box 12559, Charleston, SC 29412.
Escape rings were tested in both high and low salinity
waters of South Carolina; sublegal catch was reduced
by 90 percent in both areas, and legal catch increased
by 12 percent in low salinity, but decreased
substantially (42 percent) in high salinities due to
the loss of legal females.
- Steele,
P., and H.M. Perry (eds.). 1990. The blue crab fishery of
the Gulf of Mexico, United States: a regional management
plan. Publ. No. 21 of the Gulf States Marine Fisheries
Commission, P.O. Box 726, Ocean Springs, Mississippi
39546.
- Although
not specifically a bycatch document, this document
provides detailed information on a state-by-state basis
for the blue crab fishery of the Gulf of Mexico,
including management considerations for reducing sublegal
take, and bycatch reduction in general.
Related
Material From Outside The Region:
-
- Breen,
P.A. 1987. Mortality of Dungeness crabs caused by lost
traps in the Fraser River estuary, British Columbia. N.
Amer. J. Fish. Mgmt. 7:429-435.
- Simulating
lost traps, traps were baited then left in place for a
year. Overall, 169 Dungeness crabs were caught and
monitored; nearly all were male and the majority died,
including legal and sublegal crabs. Based on an estimated
11 percent loss rate annually in the fishery, losses of
resources due to ghost fishing might equal 7 percent of
the Fraser River District catch. Use of escape mechanisms
was recommended.
- Gagnon,
M., and M. Boudreau. 1991. Sea trials of a galvanic
corrosion delayed release mechanism for snow crab traps.
Rep. 1803, Can. Techn. Rep. Fish. Aquat.
Sci.
- Galvanic
releases were tested in conditions of the St. Lawrence
snow crab fishery. Results showed that predictable
releases could be obtained, and accidental release was
unlikely. Authors' note: In another unpublished report
by Boudreau, these were tested on 333 traps in the
fishery; none released before the predicted time, and 89
percent of the crabs escaped within two weeks after the
release opened.
- High,
W.L. 1976. Escape of Dungeness crabs from pots. Mar.
Fish. Rev. 38(4):19-23.
- Good
escapement of females and males, legal and sublegal,
occurred from disabled (open triggers and escape rings),
but was limited for operational traps. The latter was
especially true for larger crabs. At the end of 74 days,
21 percent of the large and 67 percent of the small crabs
had escaped. When the triggers were released, most left
alive escaped within three days. The results strongly
suggested that the use of triggers reduces
escapement.
- Kimker,
A. 1990. Biodegradable twine report to the Alaska Board
of Fisheries. Regional information report 2H90-05. Alaska
Dept. Fish Game, 333 Raspberry Rd., Anchorage, Alaska
99518.
- This
report, noted as containing interim and thus preliminary
data which might change, summarized tests on various
sizes of twine used in the crab fisheries. A
recommendation of reducing twine size to 30 thread was
made, and the report noted although there was no
statistical difference in breaking time between this and
much larger thread twine, on average, the release might
be 6-18 days sooner.
- Kruse,
G.H., and A. Kimker. 1993. Degradable escape mechanisms
for pot gear: a summary report to the Alaska Board of
Fisheries. Regional information report 5J93-01, Alaska
Dept. Fish. Game, P.O. Box 25526, Juneau, Alaska
99802.
- This
report, noted as containing interim and thus preliminary
data which might change, summarized tests on four release
mechanisms: 1) cotton twine; 2) galvanic time releases
{GTR}; 3) cotton twine or GTR; and 4) GTR after an
initial twine/GTR phase-in period. Cotton twine was less
expensive but less predictable, and GTR while being more
predictable were probably harder to enforce due to
differences in construction. The recommendation was some
kind of a release mechanism, with an optimum 30-day
breakage, although a longer time could be used as a
trade-off for the unpredictability.
- Muir,
W.D., J.T. Durkin, T.C. Coley, and G.T. McCabe, Jr. 1984.
Escape of captured Dungeness crabs from commercial crab
pots in the Columbia River estuary. N. Amer. J. Fish.
Mgmt. 4:552-555.
- Because
of ghost fishing concerns, escapement rates were examined
during a 28-day experiment. Sixty percent of the crabs
escaped; size, leg loss, and leg regeneration were not
factors in escapement.
- Paul,
J.M., A.J. Paul, and A. Kimker. 1993. Starvation
resistance in Alaskan crabs. Interim report. Alaska Dept.
Fish Game, 333 Raspberry Rd., Anchorage, Alaska
99518.
- This
report, noted as containing interim and thus preliminary
data which might change, noted that starvation for as
much as 30 days impacted subsequent survival of tanner
crabs even though feeding was reintroduced. This has
implications for developing release mechanisms on
traps.
- Paul,
J.M., A.J. Paul, and A. Kimker. 1993. Tests of galvanic
release for escape device in crab pots. Interim report.
Alaska Dept. Fish Game, 333 Raspberry Rd., Anchorage,
Alaska 99518.
- This
report, noted as containing interim and thus preliminary
data which might change, indicated that the use of
galvanic release mechanisms had a linear decay rate over
time, and thus could be fine-tuned for use in Alaska pot
fisheries so that they separate at any set time interval
needed to reduce crab mortality from lost
gear.
Lobster
Trap Fisheries:
-
- Hunt,
J.H., R.D. Bertelsen, C. Cox, T.R. Matthews, and W.C.
Sharp. 1995. Commercial and recreational harvest of the
spiny lobster, Panulirus argus (Latreille), in
Florida during the 1993-94 season. A report to the
Florida Marine Fisheries Commission by the Florida
Department of Environmental Protection, South Florida
Lab, 2796 Overseas Highway, Suite 119, Marathon, FL
33050.
- This
report is a detailed characterization of the fishery;
bycatch monitoring was only a part of the study.
Monitoring among nine areas, about 400 traps per area
from at least three different fishers were sampled on a
monthly basis. Contents of 100-150 traps per trip were
sampled. All totaled, 192 trips with 116 fishers
monitored the catch of 21,309 lobster traps. Bycatch
included 43 species or groups which occurred in more than
0.1 percent of the traps; 45 other species were rarer
than this occurrence. Stone crab was the most abundant
and valuable species. Grunts, grouper, snapper, and
spider crabs were also taken and occasionally harvested.
Also taken and sold were aquarium trade fishes and
invertebrates. Only 28 dead fish and invertebrates were
observed.
- Matthews,
T.R., C. Cox, and D. Eaken. 1994 (draft manuscript).
By-catch in Florida's spiny lobster trap fishery.
(submitted to Gulf and Caribbean Fisheries Institute for
publication in the proceedings of that organization).
(formal publication of the Hunt et al. 1995
report).
- An
analysis of 21,309 lobster traps found 6,972 traps with
172 species of organisms besides lobsters. Lobster catch
was consistently lower in traps that contained bycatch.
Wooden traps (90 percent of the fishery) did not have as
many fish as wire-reinforced traps; the latter caught
more commercial fishes, aquarium trade fishes, and
incidental species, although this may be because they
were fished in deeper waters than wooden traps. All
totaled, 20 dead crabs, 8 dead fish, and 5 dead
cormorants were observed in traps. Bycatch was retained
for sale or released alive.
Related
Material From Outside The Region:
-
- Blott,
A.J. 1978. A preliminary study of timed release
mechanisms for lobster traps. Marine Fish. Rev.
40:44-49.
- Release
mechanisms for New England lobster traps were examined to
reduce ghost fishing. In simulated fishing efforts,
several options for a degradable release mechanism were
tested; jute twine and steel wire were recommended for
further study in actual fishing operations.
- Pecci,
K.J., R.A. Cooper, C.D. Newell, R.A Clifford, and R.J.
Smolowitz. 1978. Ghost fishing of vented and unvented
lobster, Homarus americanus, traps. Mar. Fish.
Rev. 40:9-24.
- Unvented,
sublegal escape vent, and escape panels were tested for
American lobster traps that were tended or left as
"ghost" traps. Vented traps caught fewer and larger
lobsters. Ghost pots selectively caught large lobsters.
Approximately 25 percent of the ghost trap lobsters
suffered mortality. Bycatch of numerous species groups
was recorded, but was dominated by cancer crabs
(Cancer spp.) in hauled pots; ghost traps had
little bycatch.
- Smolowitz,
R.J. 1978. Trap design and ghost fishing: discussion.
Mar. Fish. Rev. 40:59-67.
- An
estimated 2 million pots were fished for New England
lobsters in 1973, and estimates of lost pots were 20-30
percent annually; all lost pots are considered actively
fishing units due to their construction. To be disabled,
the wooden pots must be damaged by wood-boring organisms.
Escapement of lobsters from ghost gear was estimated at
30 percent. Ghost pot mortality in 1976 was estimated at
over 1.4 million pounds. No degradable sections were
required at the time, but were recommended; however these
would produce long-term (one-year) disablement. It was
estimated that sublegal escape vents would reduce
mortality by over one-half million pounds annually.
(See also Smolowitz paper in same issue -pp.
2-8)
PELAGIC
LONGLINE FISHERIES
Pelagic
longlines, especially those targeting tuna and swordfish,
have recently been scrutinized for their unavoidable and
unwanted bycatch of prized recreational marlins and other
billfishes. Pelagic longlining is not a species-specific
effort, thus the definition of bycatch in this fishery
becomes a little more arbitrary. Numerous marketable species
may be taken, even if only one species is being targeted.
Differences in fishing practices also change the target
species. For example, tuna fishing efforts are usually
daytime sets, but swordfishing is done at night. However,
some tuna may be taken on swordfish sets, and some swordfish
may be taken on tuna sets. Thus, although perhaps not
targeted, these species would classify as bycatch; on the
other hand, given their desirability, these types of catches
should not be considered bycatch. Perhaps a more appropriate
measure of "bycatch" in this fishery is the quantity that is
discarded dead due to either no market value or regulatory
restrictions. This latter category, although providing for
an overall beneficial concept to stock management, does on
the surface appear to be wasteful. Substantial
fishery-dependent and fishery-independent data are available
to characterize the catch of the various fishing efforts,
but actual measures of bycatch and the impact of fishing on
bycatch have only recently begun to be addressed. Available
information suggests that the discard, whether voluntary or
regulatory, is less than 20 percent of the catch, and about
half is released alive. This, of course, varies by species
and region.
-
- Anderson,
E.D. 1985. Analysis of various sources of pelagic shark
catches in the northwest and western central Atlantic
Ocean and Gulf of Mexico with comments on catches of
other large pelagics. NOAA Techn. Rep. NMFS
31:1-14.
- Primarily
a paper dealing with quantifying the volume and number of
shark catches and landings from various sources, this
document does note that in one survey, sharks were 234
percent of the swordfish catch north of Cape Hatteras,
296 percent of the catch from the southeast U.S.
Atlantic, and 213 percent of the catch from the Gulf of
Mexico. These data were then used to extrapolate the
total shark catch based on the swordfish landings. The
document is a good historical summary of shark catches
and landings from a variety of fishery
sources.
- Berkeley,
S.A., and W.L. Campos. 1984. Shark by-catch in the
Florida swordfish longline fishery. A final report to
Florida Sea Grant.
- This
grant report was more formally presented in Berkeley and
Campos 1988. Some interesting information is included
here that is not in the 1988 paper, but no additional
information on bycatch, release/discard rate, etc. was
mentioned.
- Berkeley,
S.A., and W.L. Campos. 1988. Relative abundance and
fishery potential of pelagic sharks along Florida's east
coast. Mar. Fish. Rev. 50(1):9-16.
- Catch
rates of sharks were examined during 111 commercial
swordfish longline sets in the southeast Atlantic and
Florida Straits. Six hundered, thirteen sharks of 13
species were taken along with 523 swordfish; 86 percent
of the sharks were three species; 66 percent of the
sharks brought alongside were dead after overnight
soaks.
- Branstetter,
S. 1981. Biological notes on the sharks of the north
central Gulf of Mexico. Contrib. Mar. Sci.
24:13-34.
- During
69 fishery-independent shark longline sets, this survey
caught 381 sharks of 15 species and 22 teleosts of 8
species on 6,476 hooks. Non-targeted teleosts comprised 5
percent of the catch by number.
- Branstetter,
S., and G. Burgess. 1995. Bycatch on directed shark
longlines January 1994 - June 1995. A memo provided to
"An industry workshop addressing bycatch issues in
southeastern U.S. fisheries." Copy on file at the Gulf
and South Atlantic Fisheries Development Foundation, 5401
W. Kennedy, Tampa, FL 33609.
- For
144,716 hooks of commercial shark longline gear, 7,688
sharks were caught and 317 other fishes were taken along
with 15 sea turtles. All turtles were released alive.
Totals of 104 marketable fish of 6 species were
harvested; all other bycatch was released or discarded.
Specific information on percentages released/discarded
not available. (For shark catches and discards, see
Gulf
and South Atlantic Fisheries Development Foundation,
1996;
this section.)
- Guitart-Manday,
D. 1975. Los pesquerios pelagico - Oceanicas de corto
rodio de accion en la region nortoccidental de Cuba.
Cuban Sci. Acad. Oceanogr., Inst. Oceanogr. Serv. 31
(translated U.S. Dept. Com document
NMFSTT7755012).
- In
the short-range Cuban longline fishery, sharks comprised
41 percent of the catch, billfish 33 percent, and
swordfish 26 percent.
- Hoey,
J.J. 1992. Bycatch in U.S. Atlantic longline fisheries
for swordfish and tuna. pp. 61-70 In: Schoning,
R.W., R.W. Jacobson, D.L. Alverson, T.H. Gentle, and J.
Auyong (eds.). Proceedings of the national industry
bycatch workshop, Feb. 4-6, 1992, Newport, OR. Natural
Resource Consultants, 4055 21st W., Seattle, WA
98199.
- In
a summary of longline efforts, this report notes that
bycatches were reduced in the 1970's when rope/steel
(Yankee) gear was replaced by the more efficient
monofilament gear. That bycatch taken was more likely to
be alive using the latter gear as well, and thus could be
released. From an observer program and logbooks, bycatch
or catch and release information were -- northeast U.S.:
54 percent retained, 36 percent released, and 10 percent
discarded dead (this last category included shark damage
or size/quota restrictions); six species comprised 98
percent of the retained catch -- Grand Banks: marketable
fish constituted over 80 percent of the catch, and the
bycatch was primarily blue shark which are usually
released alive -- southeast U.S.: 81 percent was
marketable in one data set, and two others indicated that
approximately 33 percent to 66 percent of the catch was
shark of which in one study, 66 percent was dead -- Gulf
of Mexico: in one data set, about 25 percent of the total
catch was non-targeted swordfish/tuna species; no
disposition data on released or retained was available;
in another study of 2,185 fish caught, 69 percent was
retained, 23 percent discarded dead, and 8 percent was
released alive; in older data sets concerning Yankee
gear, swordfish were about 24 percent of the catch,
sharks 73 percent of the catch; most likely the sharks
were discarded both dead and alive.
- Hoey,
J.J. 1996. Bycatch in western Atlantic pelagic longline
fisheries. pp. 193-203 In: Baxter, B., and S.
Keller (eds.). Solving bycatch: considerations for today
and tomorrow. Alaska Sea Grant College Program Report No.
96-03, University of Alaska, Fairbanks.
- This
report summarizes the catches of over 5,000 Japanese
longline sets in the northwest Atlantic and 1,500
observed U.S. longline sets. Target species vary, but
focus on tuna and swordfish; bycatch consists primarily
of marlins and sharks with a few miscellaneous bony
fishes taken. In the Caribbean, 60 percent of the catch
was retained, 17 percent was released alive, and 23
percent was discarded dead. For the Gulf of Mexico, for
U.S. fishing efforts, 51 percent was retained, 31 percent
was discarded dead, and 18 percent was released alive.
For Japanese efforts in the Gulf in the 1970's,
approximately 50 percent of the catch was retained
(tunas) and other species were required to be released or
discarded; 19 percent of the swordfish were alive, 44
percent of the marlin were alive, and over 75 percent of
the sharks were alive when released. In another Gulf
survey where live bait was used, 69 percent was retained,
23 percent was discarded dead, and 9 percent was released
alive. In the southeast U.S., 48 percent was kept, 18
percent released alive, and 34 percent was discarded
dead. In the northeast U.S., blue sharks accounted for 19
percent of the total catch, and most were released;
overall, 49 percent was retained, 35 percent released,
and 15 percent discarded. For the Grand Banks area, blue
sharks were dominant at 44 percent of the catch and most
were alive and released; 36 percent of the catch was
retained, 34 percent released, and 30 percent discarded.
For the current U.S. fishery, a total of 1,523 sets
accounting for the capture of 50,104 individuals had over
a 50 percent survival rate at haulback. Overall, dead
discard is about 20-30 percent by number, and includes
shark- and whale-damaged fish which may account for as
much as 5 percent of the total tuna/swordfish catch.
Releasing dead fish (undersized swordfish and all marlin)
is wasteful.
- Hoey,
J.J., and J.G. Casey. 1983. Distribution and relative
abundance of sharks in the western North Atlantic as
indicated by longline catch data. Manuscript noted as
MARMAP Contribution MED/NEFC 83-14.
- Using
2,700 pelagic longline sets, the relative abundance of
nine shark species is discussed. Total catch was 105,123
teleosts and sharks, including 27,140 swordfish, 4,366
tuna, 544 billfish, and 71,827 sharks. Of the sharks,
nearly 40,500 were blue sharks, and in other Hoey papers
listed here, he notes over 90 percent of these are
released alive.
- Hoey,
J.J., and J.G. Casey. 1984. Shark longline fisheries:
gear and production characteristics. Proc. 37th Gulf and
Caribbean Fisheries Institute:169-186.
- Using
a large-scale database from a variety of
fishery-dependent and independent sources, this paper
summarizes the species composition of catches. In the
Japanese tuna fishery, of 22,316 fish caught,
approximately 13,000 tuna, 1,600 swordfish (regulatory
discard), 1,500 billfish, and 3,000 sharks were the
majority of the catch. In the U.S. swordfish catch, out
of 19,200 fish caught, species composition was dominated
by 5,000 swordfish and 13,000 sharks; tuna and billfish
together were about 250 individuals. No specific
disposition of the catches was noted.
- Gulf
and South Atlantic Fisheries Development Foundation.
1996. Commercial shark fishery observer program. A final
report to the National Marine Fisheries Service for
MARFIN award NA47FF0008 submitted by the Foundation,
Suite 997, 5401 W. Kennedy, Tampa, FL
33609.
- During
1994 and 1995, observers monitored 96 fishing trips where
276 commercial shark longlines were fished. Nearly 11,000
sharks were documented. Of 7,836 large coastal sharks
caught, 5,979 (76 percent) were retained for sale, 563 (7
percent) were discarded, and 1,294 (17 percent) were
released alive. For small coastal species, 3,037
individuals were taken, 1,773 (58 percent) were marketed,
1,232 (40 percent) were discarded (primarily used for
bait), and 32 (1 percent) were released alive. (For
finfish bycatch records, see Branstetter
and Burgess 1995;
this section.)
- Kawaguchi,
K. 1974. Exploratory tuna longline fishing in the
Caribbean and adjacent waters. Mar. Fish. Rev.
36(9):61-66.
- Exploratory
fishery-independent surveys throughout the Caribbean
produced poor results. In a year's effort around the
region 126 tunas of several species were taken, along
with 56 billfishes. The records in this paper may not be
complete, as they are focusing on total foodfish
production, not species composition.
- McEachran,
J.D. 1983. Fishery assessment of underutilized shark
resources in the northwestern Gulf of Mexico. A final
report to the Gulf and South Atlantic Fisheries
Development Foundation (GSAFDF contract 21-13-21375),
available through GSAFDF.
- As
part of a larger survey, the shark catch on commercial
swordfish longlines was monitored. During three trips,
6,000 pounds of shark carcass were produced from 113
sharks compared to 3,475 pounds of swordfish from 86
fish; one marlin was also caught. Two cruises, fishing on
the continental shelf, produced 40 sharks, two swordfish,
one grouper, one marlin, two wahoo, and two cobia. Other
commercial shark operations had no bycatch
recorded.
- McEachran.,
J.D. 1984. Fishery assessment of underutilized shark
resources in the northwestern Gulf of Mexico. A final
report to the Gulf and South Atlantic Fisheries
Development Foundation (GSAFDF contract 22-13-22881),
available through GSAFDF.
- As
a continuation of McEachran 1983, this report noted that
for commercial swordfish boats, an estimated shark to
swordfish ratio had been calculated at 1.25:1 (2:1 in
pounds). Monitoring two commercial trips for
swordfish/tuna produced 52 sharks, 60 swordfish, 47 tuna,
16 escolar/oilfish, and four billfish.
- Power,
J.H. 1993. Analysis of the longline fishery effort,
catch, and bycatch in the southwest Atlantic and Gulf of
Mexico. A final report to the National Marine Fisheries
Service, MARFIN award NA37FF0040 available from the
Coastal Fisheries Institute, Louisiana State University,
Baton Rouge, LA 70803.
- This
report analyzed the fishery effort and how it changed
seasonally and annually, but some bycatch information can
be gleaned from the tables; 18 species were considered
for multiple species association analyses. Swordfish,
bigeye tuna, yellowfin tuna, and dolphin occurred on more
than 30 percent of the sets; blue shark, mako sharks, and
hammerhead sharks (several species), occurred on more
than 10 percent of the sets. All other species occurred
on less than 10 percent of the sets. In the northwest
Atlantic, except for swordfish, occurrence of a species
on a set was less frequent than its non-occurrence by a
large margin. For the Caribbean, swordfish, bigeye tuna,
yellowfin tuna occurred on more than 50 percent of the
sets; other species occurred on 25 percent (blue shark)
to <0.5 percent (bluefin tuna) of the sets. For the
Gulf of Mexico, swordfish and yellowfin tuna were the
only species that occurred on more than 50 percent of the
sets; most other species occurred on less than 10 percent
of the sets. No disposition (release, retain, discard)
rates were presented.
- Russell,
S.J. 1993. Shark bycatch in the northern Gulf of Mexico
tuna longline fishery, 1988-91, with observations on the
nearshore directed shark fishery. pp. 19-29 In:
Branstetter, S. (ed.) Conservation Biology of
Elasmobranchs. NOAA Techn. Rep. NMFS 115.
- During
87 tuna trips in the Gulf of Mexico, 516 sharks were
recorded for 302 longline sets. Of the sharks captured,
120 were retained for sale. Mortality rate of discarded
sharks was 46 percent; higher than previous records of
15-35 percent (see Witzell, 1985) probably because of
finning (legal at the time). No percent of total catch is
given (no target species numbers). In shark-directed
sets, 1,181 sharks of 1,449 caught were retained; 18
percent was discarded, and 92 percent of that discard was
dead.
- Wathne,
F. 1959. Summary report of exploratory long-line fishing
for tuna in Gulf of Mexico and Caribbean Sea, 1954-1957.
Comm. Fish. Rev. 21(4):26.
- Exploratory
longline fishing throughout the Gulf of Mexico and
Caribbean during 1955 through 1957 was used to determine
the potential to develop fisheries in this region. During
several cruises, 203 longlines were set in the region.
Species composition, at least that recorded, was: 2,963
yellowfin tuna (72 percent), 235 other tuna (5 percent),
370 billfish including 17 swordfish (9 percent), and 562
sharks (14 percent).
- Wilson,
C.A. and J.H. Render. 1993. The application of pelagic
longline data in reducing billfish by-catch and resource
monitoring. (MARFIN NA89WC -H- MF013). Coastal Fisheries
Institute, Louisiana State University, Baton Rouge,
Louisiana.
- Statistical
analyses were performed on foreign and domestic data sets
generated by fishery observers. Foreign data from
Japanese longline vessels were collected from March 1978
through December 1981 when the Japanese abandoned the
fishery. Monitoring of the domestic longline fleet was
implemented in 1985 prior to final acceptance of the
Swordfish Fishery Management Plan in 1986. This program
was conducted by NMFS from May 1985 through March 1986
and provided observer coverage of 114 sets. Since
fishermen in this fishery targeted swordfish, most of the
sets were at night. The focus of the domestic program
shifted in 1987 to address concerns over increased
incidental catches of billfish and sharks associated with
increased efforts to catch yellowfin tuna. Most of the
observer coverage was in 1987. Data for the Gulf of
Mexico region were generated from 728 foreign longline
sets. Domestic data collected in the Gulf region were
from 80 sets where yellowfin tunas were targeted.
There
is evidence to show the association and co-occurrence of
certain species of tunas and billfish and that these
relationships may be predictable based on water
temperature. This relationship has often been noted for
pelagic resources, particularly tunas. There may be clear
implications from these relationships that are useful for
management purposes. Billfish bycatch may be reduced
through seasonal closures or changes in fishing practices
during the summer months. Seasonal closures would impact
yellowfin catch, therefore, closure length should
maximize billfish bycatch reduction while minimizing
impacts to the domestic yellowfin fleet.
- Witzell,
W.B. 1985. The incidental capture of sharks in the
Atlantic United States fishery conservation zone reported
by the Japanese tuna longline fleet. NOAA Techn. Rep.
NMFS 31.
- Using
observer data and Japanese logbooks, the catches of
sharks from the Japanese fleet operating in U.S. waters
during the 1970's was estimated. The percent contribution
of various catch species is not listed, but shark
mortality was listed at 15 percent for Atlantic and 7
percent for the Gulf.
BOTTOM
LONGLINE AND COMMERCIAL HOOK-AND-LINE FISHERIES
A
diversity of bottom longline fisheries exists throughout the
Gulf of Mexico. These different longline fisheries vary in
their take of bycatch. Gulf demersal longlining operations
vary by target species which differ dramatically in depth
and bottom type. As a result of these differences, it is
impractical to characterize bycatch associated with
longlining from a generic perspective. One exception seems
to be that sharks are a common bycatch component. From the
literature reviewed, sharks account for a high percentage of
numbers and weight of non-target species produced from
various bottom longlining practices. Because sharks are
often alive and can be effectively released unharmed, the
impacts of longlining on this resource may not have strong
detrimental implications.
Because
of the various differences in demersal longlining, the
following discussion of the fisheries that incorporate this
technique should be helpful. Note that some bottom
longlining practices no longer exist due to introduced
fishery legislation or as in the case of Kali longline gear,
non-adoption by industry.
Florida
Grouper Longline Fishery:
The
grouper industry on the west coast of Florida is the largest
fishery in the Gulf of Mexico employing bottom longline
gear. As a result of information from mandatory logbook
reports, 1,223 bottom longlining trips were recorded between
March 1994 and February 1995 (NMFS, 1995). Reported landings
for these trips totaled approximately 4.53 million pounds.
Groupers dominated landings and accounted for 70.3 percent
of the total production. Five species accounted for 83
percent of the total bottom longline landings. These were:
red grouper (Epinephelus morio), 50.3 percent;
unclassified sharks (Chondrichthyes), 14.7 percent;
yellowedge grouper (Epinephelus flavolimbatus), 10.2
percent; golden tilefish (Lopholatilus
chamaeleonticeps), 5.1 percent; and gag (Mycteroperca
microlepis), 2.8 percent.
As
indicated in Characterization of the Reef Fish Fishery of
the Eastern U.S. Gulf of Mexico, the harvest of bycatch
appears to be minimal in this fishery -- 4.5 percent of the
catch were released dead. Another major consideration
regarding take of unwanted species regards harvest of
undersized target species (discards). Red grouper have a
20-inch minimum size limit which requires that smaller fish
be returned. Mortality rates for released grouper do not
seem to be high in this fishery.
Red
Snapper Longline Fishery:
A
substantial bottom longline fishery for red snapper
(Lutjanus campechanus) was established in the Western
Gulf of Mexico in 1980 and peaked in 1983. The landings from
bottom longlining have subsequently declined. This fishery
remained viable for several years until the resource was
over-exploited by a number of vessels which entered into the
fishery. The bottom longline fishery targeted very mature
fish which were discovered on relatively smooth bottom
contours away from reef structures. A tremendous decline in
red snapper produced from longlines occurred after 1991 due
in large part to the 1990 prohibition against fishing this
gear inside of 50 fathoms (Goodyear, 1995).
The
majority of red snapper produced by bottom longlines were
within the 50 fathom contour. When federal regulations were
passed to ban longlines from inside this depth, the vast
majority of longliners either changed their fishing
operation (converted back to power reels) or redirected
bottom longlining to other fisheries (grouper or tilefish).
Red snapper are still harvested with longlines outside of
the 50-fathom contour in the Western Gulf of Mexico, but
these fish are taken incidentally to grouper operations.
Because there is a restricted commercial season for red
snapper, it is perceived that the majority of incidentally
taken red snapper outside of 50 fathoms are released. There
is no known study or documentation regarding survivability
of these fish when captured from such depths. Furthermore,
documentation of quantities of red snapper taken in the
western grouper longline fishery does not exist. A need for
such data merits consideration.
Golden
Tilefish Longline Fishery:
The
bottom longline fishery for golden tilefish (Lopholatilus
chamaeleonticeps) has fluctuated since the late 1970's.
Compared to the grouper fisheries, it is dwarfed
substantially by its limited landings. As indicated in NMFS
(1995), tilefish are often harvested as an incidental
species in the Eastern Gulf. Only a few vessels target
golden tilefish in the western Gulf, and these efforts are
contingent upon receiving adequate prices for a seafood
species which has been traditionally subjected to extensive
market fluctuations. Another problem with this fishery
relates to the very slow biological growth and development
of this species. The tilefish longline fisheries throughout
the Gulf and Atlantic have never been able to maintain
sustainability when pursued by a number of vessels. Bycatch
production from the tilefish fishery appears to consist
mostly of shark. The catch composition of these sharks are
compromised mostly of dogfish sharks, Squalus and
Centrophorus.
Western
Gulf Grouper Longline Fishery:
The
bottom longline fishery for grouper is the largest of the
demersal longline fisheries in the western Gulf. The
magnitude of this fishery is not known, however it appears
to have diminished over the last decade. The loss of red
snapper longlining inside of 50 fathoms inhibited the
viability of this fishery because it reduced its
versatility. Data for this fishery are limited, however the
bycatch species appear to be compromised primarily of sharks
and eels (especially banded shrimp eels). It appears that
relatively little other bycatch exists for this fishery
except that of red snapper. Because the Gulf red snapper
fishery has a quota which is usually met in less than two
months, grouper vessels harvesting red snapper must return
these fish if they are harvested outside of the season.
There is little knowledge relative to the extent of red
snapper that are incidentally harvested outside of 50
fathoms, but it is thought to be considerable in some areas
of the Western Gulf. A scarcity of information also exists
regarding the survival of red snapper that are harvested and
then released from grouper longlines in waters outside of
the 50-fathom depth.
Kali
Pole Longline Fishery:
Efforts
to introduce Kali pole longlines into the Gulf of Mexico
were never successful. Difficulties in handling the gear and
expensive gear losses greatly inhibited the adaptation of
this longlining system. Limited data exists regarding the
take of bycatch with this gear (Bankston
and Horst 1984)
(McEachran
1985)
(
Russell, Gutherz, and Barans 1988).
Traditional
Hook and Line Fishery:
The
hook and line fishery for various seafood species represents
one of the oldest fishing techniques in the Gulf of Mexico.
The fishery for red snapper in the Gulf of Mexico began over
150 years ago off Pensacola, FL (Goodyear, 1995). Currently
this fishing practice is limited almost entirely to harvest
of reef fish and is employed throughout the Gulf of Mexico.
Although commercial hook and line fishing is a long
established fishing technique, there is a clear paucity of
information concerning its production of bycatch. The lack
of information regarding incidental take of non-target
species is somewhat surprising because the reef fisheries
have undergone considerable studies and management measures
under the direction of the Gulf of Mexico Fisheries
Management Council (GMFMC). Perhaps the apparent absence of
concern regarding bycatch from commercial hook and line
fisheries is an indication that no problems are thought to
exist.
Closely
associated with concerns for bycatch in the commercial hook
and line fishery are discards within the various fisheries
-- especially the red snapper fishery. The introduction of
size limits for various species brought about the
requirement to release undersized individuals from the
targeted fishery. A minimum size limit was imposed upon red
snapper in 1984 by the GMFMC, and size limits have increased
from 12 inches to 15 inches since that time. Goodyear (1995)
reported that an observer program to collect data about the
reef fish fisheries in the Gulf of Mexico was initiated in
1995, and included some red snapper trips aboard handline
vessels. Among other information, the observers recorded the
lengths and fates of the catch, including the discards. Data
from these trips during the 1995 season indicated that 40.7
percent of the red snapper caught were discarded. By weight
these fish constituted about 18.6 percent of the red snapper
catch. The observations were of fish caught at an average
depth of 40 m (range 22 to 62 m) generally offshore
Louisiana and east Texas. Only about 1.6 percent of the
catch was discarded dead, but Goodyear reported that most of
the discarded fish had either stomachs or eyes protruding
and many of these probably suffered delayed
mortality.
Goodyear
further noted that reef fish logbooks also contain fields
for reporting the number of discarded fish since 1993. Most
captains have left that field blank. However for those
captains who reported discards, the fraction of catch
discarded by number was about 31 percent in 1993, 28 percent
in 1994, and 30 percent in 1995. These rates are less than
the observer data indicated. Small sample sizes or different
geographical coverage between the two sources may account
for these differences.
Resource
managers, fisheries scientists, commercial fishermen, and
recreational fishermen continue to debate the magnitude of
mortality regarding discards -- especially red snapper.
Although field experiments have taken place to determine
release mortality, this is a very recondite task. Cages have
been used to hold discarded red snapper for study. These are
lowered back into the water at various depths and held for
periods of time to determine survival. Gitschlag and Renaud
(1987), Parker (1985) and Render and Wilson (1994) have
performed such experiments. The commercial industry and
others have questioned the feasibility of lowering fish back
into the water column to determine mortality rates of
released fish. This practice introduced forced recompression
of fish, particularly those with protruding stomachs.
Attempts were made by Gitschlag and Renaud, as well as
Parker, to obtain mortalities of fish released at the
surface. These efforts have been limited in success because
of visibility problems with divers and variations in
abundance of predators which would impact released
discards.
The
survival of discards presents a dilemma to the red snapper
hook and line fishery. Gitschlag and Renaud (1987) report,
"Neither cage experiments nor surface release experiments
independently provided an accurate estimate of survival for
red snapper released at different depths due to inherent
differences in methodologies. The resulting survival range
did not account for mortality attributable to predation.
Efforts to quantify predation on released snapper were
unsuccessful, and values for predation rates could only be
assigned arbitrarily for the purpose of discussion. It is
doubtful that accurate estimates of predation rates will
ever be determined due to potentially insurmountable
difficulties with in situ methodologies." Because the
magnitude of red snapper discards is so extensive, mortality
rates of released fish continues to be an important
consideration. Research efforts have provided some clarity
regarding the impacts of discard mortality, but definitive
answers to this important question do not and may not ever
exist.
-
- Bankston,
D., and J. Horst. 1984. Exploratory bottom longline
fishing off Louisiana's coast. Technical Series No. 1.
Coastal Ecology and Fisheries Institute, Louisiana State
University, Baton Rouge, Louisiana.
- Exploratory
longline sets were made off the Louisiana Coast utilizing
sample quantities of gear. The report focuses upon 122
longline sets deployed in various depths of water
extending from 41 to 218 fathoms. Approximately 65 of
these sets were made utilizing Kali longline gear arrays.
The remainder of the sets (approximately 57) incorporated
more traditional bottom longlining gear. Target species
were red snapper, yellowedge grouper, and
tilefish.
A
description of bycatch species was included for each set.
The primary bycatch species consisted of dogfish and
other shark species, eels, and hake. From Gary Graham's
experience, the majority of shark species (certainly
dogfish) and eels are brought to the surface alive and
can be released in good condition. According to this
report, the hake were not marketed, but a potential for a
small market exists. From Gary Graham's experience, hake
are excellent bait and should be utilized for such during
longlining activities. This report did not address
bycatch production except to list the numbers of
individual species taken during each set.
- Christian,
P.A., M.V. Rawson, D.L. Harrington, and L.G. Parker.
1985. Bottom longlining off the southeastern U.S. coast,
Report to Gulf and South Atlantic Fisheries Development
Foundation, and National Oceanic and Atmospheric
Administration, U.S. Department of Commerce through the
National Sea Grant Program (Grant # NA80 AA-D-0091 and
NA84 AA-D-0072).
- This
report gives a perspective of demersal longlining
operations and gear. Technical aspects regarding
deployment and retrieval of gear are presented. Fishing
locations where commercial quantities of fish were
located are listed. Bycatch data does not exist other
than a discussion regarding the use of bycatch for
bait.
- Cody,
T.J., B.E. Fuls, G.C. Matlock, and C.E. Bryan. 1981.
Assessment of bottom longline fishing off the central
Texas coast, a completion report, Texas Parks and
Wildlife Department, Coastal Fisheries Branch Management,
Management Data Series Number 22.
- Utilizing
sample quantities of bottom longlining gear, a study of
potential finfish production was performed from February
1978 to February 1980 along the central Texas coast. Of
the 104 samples obtained, 91 came from the inshore zone
within the 50-fathom depth contour. Thirteen additional
samples were taken in random sets deployed in depths
ranging from 55 to 228 fm. Approximately 21 sets were
made in depths of 10 fathoms or less. Sample sets
normally consisted of 100 hooks, but ranged in numbers
from 50 to 250 hooks.
Records
of all species of finfish harvested from this study are
presented. Atlantic sharpnose shark (Rhizoprionodon
terraenovae) was the most abundant species caught
during the study; it represented 78.4 percent of the
number and 69.5 percent of the weight caught. Although
this study did incorporate longline sets in waters which
were later exploited for red snapper and grouper, only 17
red snapper (Lutjanus campechanus) and five
yellowedge grouper (Epinephelus flavolimbatus)
were taken from the sampling. Several deepwater sets on
the tilefish grounds were made and 29 golden tilefish
(Lopholatilus chamaeleonticeps) were taken in
these samples.Although some sets were made outside of
fishing grounds normally utilized for past or traditional
commercial longlining activities, recorded catches from
certain areas do contain data which can compliment
bycatch data regarding bottom longlining.
- Dixon,
R.L. (Abstract only) Survival rates of released
undersized reef fishes. NMFS Beaufort Laboratory.
Beaufort, NC 28516.
- To
prevent growth over-fishing the South Atlantic Fishery
Management Council established size limits for 22 species
of reef fishes. However, fishermen reported that many
released undersized fishes floated and were presumed to
die. Observers were placed aboard headboats and
commercial handline vessels to directly observe the
fraction of released undersized reef fishes that floated
so estimates of maximum acute mortality could be made.
Approximately 4,900 released fish representing 28 species
were observed. Survival was estimated for 15 species: red
porgy (Pagrus pagrus), whitebone porgy (Calamus
leucosteus), vermilion snapper (Rhomboplites
aurorubens), red snapper (Lutjanus
campechanus), lane snapper (Lutjanus
synagris), gray snapper (Lutjanus griseus),
mutton snapper (Lutjanus analis), yellowtail
snapper (Ocyurus chrysurus), gag (Mycteroperca
microlepis), scamp (Mycteroperca phenax), red
grouper (Epinephelus morio), speckled hind
(Epinephelus drummondhayi), black sea bass
(Centropristis striatus), white grunt (Haemulon
plumieri), and greater amberjack (Seriola
dumerili). Total survival rates ranged from 70
percent (red snapper) to 100 percent (whitebone porgy).
Tests were made for effects of region, surface water
temperature, depth of capture, and depth of
capture-surface water temperature interaction on rate of
survival. There was a correlation between decreasing rate
of survival and increasing depth for gag, speckled hind,
white grunt, and black sea bass ( = 0.05).
- Gitschlag,
G.R., and M.L. Renaud. 1987. Field experiments on
survival rates of released red snapper with a discussion
of their impact on yield models and minimum size limits,
NMFS Southeast Fisheries Center, Galveston,
Texas.
- Survival
of red snapper (Lutjanus campechanus) discards was
estimated using two types of experiments--a cage survival
study and a surface release study. In addition, size by
depth relationships for red snapper off the Texas coast
were investigated. Results from cage studies indicated 68
percent survival of snapper captured at 50 m (165 ft.).
The author acknowledged that predation upon normally
released fish did not occur with the use of cages in
their study. Surface release data showed survival rates
of 99 percent, 89 percent, and 64 percent at 21-24 m
(70-80 ft.), 30 m (100 ft.), and 37-40 m (120-130 ft.),
respectively, for red snapper measuring less than 30 cm
(12 inches) fork length.
- Goodyear,
P.C. 1995. Red snapper in U.S. waters of the Gulf of
Mexico, Southeast Fisheries Science Center, Miami
Laboratory, NMFS, Contribution:
MIA-95/96-05.
- This
comprehensive report of red snapper covers biological
characteristics, catch trends, discards, commercial and
recreational catches, mortalities, stock assessments,
etc. Little information indicating bycatch of other
species is included, however mortality rate of snapper
discards is discussed.
- Horst,
J., and D. Bankston. 1987. Bottom longlining fishing off
Louisiana's Coast, Prepared for Coastal Fisheries
Institute and Louisiana Sea Grant College
Program.
- This
document describes production of marketable fish
harvested from bottom longlining efforts and limited
snapper reel production off the Louisiana Coast. Results
from approximately 76 bottom longline sets are
documented. A variety of locations and bottom types were
fished during this study. Depths ranging from 21 to 218
fathoms were fished. A total of 1,273 salable fish
weighing 8,313 lb. (round weight) were caught.
Three
species, yellowedge grouper (Epinephelus
flavolimbatus), red snapper (Lutjanus
campechanus), and golden tilefish (Lopholatilus
chamaeleonticeps) were the targeted species for the
longlining operation. Additional fishing effort was
directed toward harvest of reef fish with snapper reels
during certain nighttime periods. Vermilion snapper
(Rhomboplites aurorubens) was the primary
commercial species taken from 14 locations in depths
ranging from 26 to 47 fathoms. Bycatch utilizing snapper
reels from these fishing efforts is listed in the
production tables. Bycatch consisted primarily of giant
snake eels (237), sharks (211), hakes (77), and moray
eels (31). A cruise log indicating the location and catch
of each set is included in the report.
- Hueter,
R.E. 1994. Bycatch and catch-release mortality of small
sharks in the Gulf coast nursery grounds of Tampa Bay and
Charlotte Harbor. (MARFIN NA17FF0378). Mote Marine
Laboratory, Sarasota, Florida. (This document also
contains both recreational hook-and-line and gillnet
info).
- This
two-year project assessed the relative importance of two
estuaries of the southwest Florida Gulf Coast, Tampa Bay
and Charlotte Harbor/Pine Island Sound, as shark nursery
areas, and examined potential fishing mortality of these
young sharks in the nurseries. Fishery-independent and
fishery-dependent surveys for juvenile and small adult
sharks were conducted in the study areas from November
1991 to October 1993. This project is discussed in more
detail under the headings of "gillnet/trammel net" and
"recreational hook-and-line" elsewhere in this report,
but of note here is that one of the fishery-independent
methods used in this survey was bottom longlining.
Longline sets accounted for 108 gear sets fishing for
488.5 hours with a total catch of 87 sharks of 8 species,
121 skates and rays of 5 species, and 518 bony fishes of
16 species. Interestingly, one of the species listed as
being taken on the longline gear was yellowfin menhaden
(Table 22). In general, the longline was not nearly as
effective as gill nets in catching small sharks. Although
a classification system was used to assess the condition
of the catch when tagged and released, mortality by gear
types is not addressed except in the following manner:
"As of 7 December, 1993, a total of 52 shark recaptures,
representing 4.2 percent of all tagged sharks at liberty,
were reported. Longest time at liberty was 358 days and
longest distance traveled was a minimum of 105 nautical
miles. Based on tag return data, we estimate an average
of 34.8 percent of sharks released alive after being
caught do not survive the catch-and-release event. The
delayed mortality, combined with an immediate at-the-boat
observed mortality of 30.6 percent, yields an estimated
total mortality from a single fishing event of 54.8
percent of all juvenile and small adult sharks caught.
These mortality estimates apply primarily to sharks
caught in gill nets within the study areas."
- Huntsman,
G.R., W.R. Nicholson, and W.W. Fox Jr. 1982. The
biological bases for reef fishery management-proceedings
of a workshop held October 7-10, 1980 at St. Thomas,
Virgin Islands of the United States.
- Production
of snapper and grouper species harvested aboard research
cruises utilizing electric and mechanical reels is
documented. Areas sampled are Surinam, Guyana, Honduras,
Antigua, Barbuda, and Pedro Bank. Production relative to
bottom type is characterized. Documentation of bycatch of
non-commercial species is not indicated.
- Kawaguchi,
K. 1974. Handline and longline fishing explorations for
snapper and related species in the Caribbean and
adjacent waters, Mar. Fish. Rev. 36
(9):8-31.
- Explorations
for snapper and related reef fish were conducted on
under-exploited areas in the Caribbean. This report
examines catch results obtained relative to fishing
grounds, water depth, bottom type, fishing season, and
species composition. Handline production was documented
and experimental bottom longline sets were deployed.
Three project vessels spent a total of 382 days
conducting exploratory fishing.
The
report includes results from 382 days of fishing.
Production from this period equaled 291,000 pounds of
fish consisting of 51 percent snapper (Lutjanidae), 34
percent jacks (Carangidae), 6 percent groupers
(Serranidae) and 9 percent other mixed species. Because
this work was conducted in the Caribbean, application to
bycatch production in Gulf of Mexico waters may have
considerable limitations. It should be noted that red
snapper (Lutjanus campechanus) traditionally
harvested in the Gulf and South Atlantic do not occur in
Caribbean waters.
This
report includes results from 87 bottom longline sets
throughout the Caribbean. It is indicated that production
from longline operations yielded 1,888 pounds of fish.
The catch weight was about 15 percent (17 percent in
number) snapper, 21 percent (19 percent in number)
grouper, 43 percent (25 percent in number) jacks, and 21
percent (39 percent in number) sharks and other
fish.
- McEachran,
J.D. 1985. Assessment of demersal reef fish resources and
gear technology for the northwest Gulf of Mexico,
prepared for the Gulf and South Atlantic Fisheries
Development Foundation, Inc. Contract
25-13-24213/9224.
- Production
from Kali and demersal longline sets are documented in
this report. Forty-one sets consisting of 20,470 hooks
were conducted utilizing Kali gear. Twenty-five sets
utilizing 4,490 hooks were made with traditional bottom
longlines. Total catch of marketable species is listed
from each of the two gear types. Bycatch is indicated as
miscellaneous fish and represents a relatively low number
in regard to commercial species landed.
- Nelson,
W.R., and J.S. Carpenter. 1968. Bottom longline
explorations in the Gulf of Mexico, A report on Oregon
II's first cruise, Commer. Fish. Rev. 39
(10):57-62.
- One
hundred-nineteen sample longline sets consisting of
36,100 hooks were set off Texas/Louisiana, Campeche Bank,
West Florida and the Northern Gulf. Bycatch quantities
and species are not documented in this report, however
incidental shark production is included (32 percent of
the total catch). The gear was set in a broad range of
depth, extending from 20 to 300 fathoms. This report
indicates that food fish consisted of 77 percent of the
total catch off Texas. The second most productive area
for food fish (74 percent of the total catch) was
Campeche Bank.
- NMFS.
1995. Characterization of the reef fish fishery of the
eastern U.S. Gulf of Mexico Report to the Gulf of Mexico
Fishery Management Council Reef Fish Management
Committee, Key West, Florida, July 17-18, 1995. Prepared
by the Galveston and Miami Laboratories.
The data encompass eleven trips aboard seven bottom
longlining vessels from April 1994 through February 1995.
Three-hundred-eleven sets (227,607 hooks) were sampled in
the Eastern Gulf of Mexico. Two-hundred thirty-six sets
targeted red grouper with the remaining seeking
yellowedge grouper and blueline tilefish. The study
indicates that 5,016 fish of 85 taxa were caught.
Approximately 55.9 percent of the individuals were kept,
28.3 percent were released alive, 9.4 percent were
retained for bait, 4.5 percent were released dead and 1.8
percent were released with an unknown fate.
By
number, red grouper comprised the majority (51 percent)
of the kept category. Yellowedge grouper accounted for 22
percent, followed by gag and blueline tilefish at six
percent, scamp at four percent, speckled hind at two
percent and red porgy at one percent. All other species
combined accounted for nine percent.
Three
thousand forty-seven red grouper were caught using
longlining gear during this study. Forty-seven percent of
the fish caught were less than 20 inches in length
(undersized). Of these, 83 percent were released alive,
12 percent were released dead, three percent were
released with an unknown fate and one percent were used
for bait.
- Parker,
R.O. Jr. 1985. Survival of released red snapper. Progress
report to Gulf of Mexico Fisheries Management Council.
(Unpublished data).
- Initially,
the relationship of the depth of capture to survival of
released fish was tested in the laboratory. Fish captured
from various depths (18 to 122m) were transported to the
laboratory and observed over a period of three weeks and
mortality was recorded. Later, to remove the reduced
pressure and transportation effects, which could cause
substantial biases, cage studies were initiated on the
fishing grounds.
Mortality
of red snapper discards was evaluated through cage
studies in the Atlantic Ocean and the Gulf of Mexico.
Fish measuring up to 38 cm (15 in) FL were used and 79
percent (11 of 14) survival rates were observed at 24 m
(78 ft) depths in the Atlantic Ocean. An 89 percent (39
of 44) survival rate was noted at 30 m (100 ft) depths
off Texas in the Gulf of Mexico.
- Prytherch,
H.F. 1983. A descriptive survey of the bottom longline
fishery in the Gulf of Mexico, NOAA Technical Memorandum
NMFS-SEFC-122.
- A
survey was conducted in three main areas of concentration
of the longline fisheries: the eastern Gulf off St.
Petersburg, FL, the northern Gulf off Panama City, FL and
in the western Gulf off the South Texas area. Information
was acquired through interviews with longline vessel
crews and through use of NMFS observers.
Observers
were deployed aboard at least one vessel fishing in each
of the principal longlining areas and catch data were
obtained. In the eastern Gulf, eels and shark comprised
the primary bycatch species as represented from one
10-day trip. It seemed apparent from the data that
grouper were being targeted. Six different vessels were
observed in the northern Gulf and sharks and eels again
comprised the bulk of the bycatch (species were not
indicated). Grouper and tilefish comprised the bulk of
the catch. In the western Gulf of Mexico, one red snapper
longline trip was documented. Sharks comprised the
majority of the bycatch (species not listed) with an
occasional scorpionfish being harvested (four, three, and
three harvested respectively in three days, followed by
no scorpionfish harvested in the remaining six days of
the trip). Very little bycatch was indicated in any of
the data from the three areas.
- Render,
J.H., and C.A. Wilson. 1994. Hook-and-line mortality of
caught and released red snapper around oil and gas
platform structural habitat. Bulletin of Marine Science.
Vol. 55 (2):1106-1111.
- A
study to determine the mortality of released red snapper
was conducted off Louisiana. Net cages were used to hold
282 red snapper caught in depths of 21m (69 feet). A 19.7
percent mortality was observed through the study. No
observed significant variation in mortality rate was
noted for treatment (deflation of gas bladder) or length
of time in net.
- Russell,
M.G., E.J. Gutherz, and C.A. Barans. 1988. Evaluations of
demersal longline gear off South Carolina and Puerto Rico
with emphasis on deep-water reef fish stocks. Mar. Fish.
Rev. 50 (1):26-31.
- Comparative
gear trials were conducted during three cruises in two
geographical areas. The RV Oregon sampled in a
specific (0.8 km2) area off Charleston, SC in
a depth of 100-110 fm. Production of traditional bottom
longlining gear was compared to that of Kali pole arrays.
Similar studies were conducted in the Caribbean depths
ranging from 38-324 fm.
Catch
analysis is presented and bycatch composition can be
abstracted from the data. The data does not indicate that
commercial quantities of fish were encountered in these
trials which might deter actual determination of bycatch
impacts from commercial operations.
- Russell,
S.J. 1994. Mackerel and reef fish bioprofile and
catch/effort data collection from the northern Gulf of
Mexico (MARFIN NA37FF0042) Russell Research Associates,
Grosse Tete, Louisiana 70740.
- This
report summarizes the results obtained during the project
period of April 1, 1993, through December 31, 1993, of a
continuing study to record catch/effort and bioprofile
data from the mackerel and reef fish fisheries in the
northern Gulf of Mexico. A total of 80 interviews (34
from bandit reel boats, 9 from bottom longline boats, 1
from a charter/party boat selling its catch, 23 from
mackerel trolling boats, 2 from boats fishing tunas with
bandit reels, 1 from a fish trawl boat, 1 from a strike
net boat, and 9 from vessels carrying multiple gear such
as bandits and longlines, or bandits, and fish traps)
were obtained from commercial fishermen targeting reef
fish and king mackerel during the 7 ½ months of
actual field sampling. A total of 3,833 fish were
measured during the project period, and 3,679 of these
fish were also weighed. Table 2 gives a comparison
between different gear of the proportion of species
comprising the sampled catches (percent by weight in
gutted pounds except for gray triggerfish which is always
landed whole). Since the surveys were conducted dockside,
there is no indication of the amount of at-sea release
which occurred. However, primary target species landed
made up the majority of catch for mackerel trolling (97.8
percent king mackerel), and bottom longlining (82.1
percent grouper and 13 percent tilefish). The catches
landed by bandit-reel fishermen were more diverse (39.6
percent snappers, 32 percent jacks, 13 percent groupers,
4.1 percent triggerfish, and 3.2 percent
tunas).
- Wilson,
R.R. Jr., and K.M. Burns. 1996. Potential survival of
released groupers caught deeper than 40 m based on
shipboard and in-situ observations, and tag-recapture
data. Bulletin of Marine Science. 58(1):234-247.
(This work also applies to the recreational hook-and-line
fishery).
- In
this study, shipboard and in-situ observations were used
to determine the potential post-release survival rate of
groupers, chiefly red grouper (Epinephelus morio),
caught from between 44 and 75 m on the central west
Florida shelf. Potential survival rates were then further
evaluated in combination with data from a tag and
recapture study (3,818 releases) in the same area and
time period. Potential survival rates for released red
grouper and scamp (Mycteroperca phenax) caught
shallower than 44 m were very high (86 percent to 100
percent) for up to eight days following release.
Undersized grouper (<50.8 cm) caught from both
shallower and deeper than 44 m, then tagged and released,
were found to survive long enough to reach legal size.
For grouper caught deeper than 44 m, however,
tag/recapture data and in-situ observations indicate that
potential survival rates are too low (<33 percent) for
the 50.8 cm (20 inches) size rule to be effective in
increasing yield.
- Wolf,
R.S. 1974. Minor miscellaneous exploratory/experimental
fishing activities in the Caribbean and adjacent waters.
Mar. Fish. Rev. 36(9):78-87.
-
- In
a follow-up effort to that described by Nelson and
Carpenter (1968), one of several miscellaneous fishing
tactics used was deepwater bottom longlining. This was
attempted off Guyana to French Guiana in 100 to 225+
fathoms. During 43 sets, 7,118 hooks were deployed and
caught 224 tilefish, 33 groupers, and 13 other fishes
(noted as mostly shark).
RECREATIONAL
SHRIMP FISHERIES
Authors'
note: This section also includes information on
bycatch from bait shrimping and other small nets or
nearshore shrimping activities.
Recreational
shrimping is defined by most Gulf Coast states as the taking
of shrimp for personal use or consumption (for example:
eating or bait) and not for sale, trade, or commercial use.
Recreational shrimpers use small shrimp trawls with a
maximum headrope length of 16 feet, (20 feet in Texas) or
cast nets with a maximum size of 12 to 24 feet, (varies by
state) and are required to have a recreational shrimping
license and/or a recreational fishing license. The total
costs of these for each state are (for residents): $15 in
Mississippi, $16 dollars in Alabama, $13.50 in Florida, $36
in Louisiana, and $43 in Texas. In Florida, recreational
shrimpers are prohibited from using otter trawls as of
January 1, 1996. Thus, Florida recreational shrimpers can
only use the following gear: landing or dip nets with a
96-inch maximum perimeter, cast nets with maximum radius of
12.5 feet, push nets, one frame net with a maximum opening
of 16 feet around the perimeter, and shrimp traps. State
limits for shrimp catches are: 50 pounds per person per day
in Mississippi, five gallons per person per day in Alabama,
five gallons per vessel per day in Florida, 50 pounds per
person per day or 100 pounds per boat per day in Louisiana,
and 15 pounds per person per day in inside waters or 100
pounds per boat per day in outside waters in Texas.
Recreational shrimp size limits are restricted to 68 shrimp
per pound in Mississippi, no size limit in Alabama, 47
shrimp heads-on (or 70 headless) per pound for Florida, 100
shrimp (white only) per pound in Louisiana, and 50 shrimp
per pound in inshore waters or 100 shrimp per pound for
outside waters in Texas.
A 1991
survey of Alabama's licensed recreational shrimpers combined
with independent trawling data estimated the recreational
shrimp bycatch to be about 1,222,000 lb. of fish compared to
99,000 lb. of shrimp. In the 1970's recreational shrimp
catches along the Gulf coast varied from 23,000,000 lb. in
Louisiana to 204,000 lbs. in Alabama. During this same time
period, recreational shrimping finfish bycatch for Alabama,
Mississippi, and Louisiana was estimated at 110,200,000 lb.
annually. Trinidad's artisan trawlers were reported to have
catch ratios of 9 lb. finfish to 1 lb. shrimp and 14.7 lb.
bycatch to 1 lb. shrimp.
Reported
fish species in the bycatch from recreational and bait
shrimping activities include: pinfish (Lagodon
rhomboides), pigfish (Orthopristis chrysoptera),
silver jenny (Eucinostomus gula), Atlantic croaker
(Micropogonias undulatus), weakfish (Cynoscion
regalis), spot (Leiostomus xanthurus), yellowfin
and Atlantic menhaden (Brevoortia smithi and
Brevoortia tyrannus), hard-head and gafftopsail
catfish (Arius felis and Bagre marinus), with
seasonal catches of gray snapper (Lutjanus griseus),
lane snapper (Lutjanus synagris), gag grouper
(Mycteroperca microlepis), and hogfish
(Lachnolaimus maximus). Although bycatch to shrimp
ratios and bycatch mortality rates tend to be highest during
the summer and fall, differences in mean CPUE in number and
weight exist among seasons and location. Seasonal and
location shifts in species composition are attributed to
migration and various marine and environmental
influences.
Net-modification
trawl experiments showed that the FFE (Florida Fish Eye),
AFAT (Accelerator Funnel mounted in front of a TED), and
AFBT (Accelerator Funnel mounted behind TED) designs were
relatively effective and consistent at reducing small fish
bycatch in various estuarine habitats, while the SWFD
(Seaweed Fish Excluder), HWED (Hummer-wire Deflector), FFED
(Florida Finfish Excluder Device), and the Fish Shooter were
somewhat inconsistent in their efficiencies. The reason for
this was suggested to be due to different environmental
factors associated with the various habitats.
An
electrified trawl experiment caught an average of 36.7
percent more shrimp than a roller-frame, while roller frame
trawls had lower bycatch mortality rates. Roller frame and
otter trawls would be more effective at bycatch reduction if
seasonal and temporal closures coincided with times of fish
abundance, although otter trawls are thought to need gear
modifications as well.
-
- Campos,
W.L., and S.A. Berkeley. 1986. Impacts of the commercial
fishery on the population of bait shrimp (Penaeus
spp.) in Biscayne Bay. Final report to Dade County
Department of Environmental Resources
Management.
- This
study addressed the concern that the live bait shrimp
fishery harvest represented a significant removal of food
from Biscayne Bay. Relative contribution of the
commercial fishery to total mortality required accurate
estimates of shrimp population size. This was
accomplished by using an electrified trawl which captured
a relatively constant percentage of available shrimp
(36.7 percent more than a roller frame trawl). Total
catch by the bait shrimp fleet, estimated monthly by
monitoring the commercial fishery, was used to calculate
the percent harvested by the bait fishery. Total
mortality, natural mortality and fishing mortality were
also estimated. The commercial fishery and ecosystem
absorbed (monthly) 23 percent and 26 percent of the male
and female non-migrating population, respectively.
Emigrating shrimp stocks had losses of 56 percent (male)
and 57 percent (female) due to fishing, natural means and
emigration. The biggest source of loss was through
natural means, while fishing accounted for only 21
percent. Approximately four percent were lost each month
to emigration. Thus, the direct impact of the bait shrimp
fishery on the shrimp population was relatively
small.
- Coleman,
F.C., and C.C. Koenig. (n.d.). Florida inshore shrimping:
experimental analysis of bycatch reduction. Final report
to Florida Department of Natural Resources. 3900
Commonwealth Blvd., Tallahassee, FL
32399.
- The
efficiencies of five bycatch reduction devices (TED -
turtle exclusion device, FFED - Florida finfish excluder
device, AFAT - accelerator funnel mounted in front of a
TED, AFBT - accelerator funnel mounted behind TED and
AFAT, HWED - hummer-wire deflector, and SWFE - seaweed
fish excluder) were evaluated in three representative
estuarine habitats. The AFAT and the AFBT designs were
the most effective and consistent at reducing small fish
bycatch under various estuarine habitats, while the SWFE,
HWED, and the FFED were inconsistent in their
efficiencies, possibly due to different environmental
factors in the various testing sites.
- Coleman,
F.C., C. Koenig, and W.F. Herrnkind. 1993. Survey of
Florida inshore shrimp trawler bycatch. Annual report to
Florida Department of Natural Resources. 3900
Commonwealth Blvd., Tallahassee, FL
32399.
- The
catch of inshore bait shrimpers and food shrimpers was
sampled in the Big Bend, South Florida, Northeast
Florida, and the Panhandle. The most abundant fish in the
bycatch of bait shrimpers (using roller-frame trawls
operating in seagrass beds) were pinfish (Lagodon
rhomboides), pigfish (Orthopristis
chrysoptera), silver jenny (Eucinostomus
gula), with gray snapper (Lutjanus griseus),
lane snapper (Lutjanus synagris), gag grouper
(Mycteroperca microlepis), and hogfish
(Lachnolaimus maximus) being more common only
during the spring and summer. Bycatch reduction from
roller frame trawlers was suggested to be more effective
if seasonal and temporal closure of seagrass beds
coincided with time of abundance, while otter trawlers
were suggested to need gear modification as well as
seasonal and temporal closures.
- Coleman,
F.C., C.C. Koenig, and W.F. Herrnkind. 1995. Survey of
Florida inshore shrimp trawling by-catch and preliminary
tests of by-catch reduction devices. Annual report to
Florida Department of Natural Resources. 3900
Commonwealth Blvd., Tallahassee, FL
32399.
- Bycatch
reduction device experiments (FFED - Florida finfish
excluder device, SWFED - seaweed fish excluder device,
and AF - accelerator funnel) were conducted in several
Florida inshore shrimping areas using otter trawls in
coordination with roller frame studies to establish the
geographic distributions and seasonality of finfish,
portunid crabs, and penaeid shrimp. Although their was no
indication of potential influence of bycatch on
population sizes, some of the more common components of
the bycatch included pinfish (Lagodon rhomboides),
pigfish (Orthopristis chrysoptera), spotfin mojara
(Eucinostomus argenteus), Atlantic croaker
(Micropogonias undulatas), spot (Leiostomus
xanthurus), bigheaded searobin (Prionotus
tribulus), and gulf toadfish (Opsanus
beta).
- Continental
Shelf Associates, Inc. 1992. Commercial food shrimp
fishery impacts on by-catch in the lower St. Johns River,
Florida. Draft final report to Florida Department of
Natural Resources. 3900 Commonwealth Blvd., Tallahassee,
FL 32399.
- Species
composition and mortality of otter trawl bycatch showed
that the fishes most commonly caught were sciaenids
(Atlantic croaker, Micropogonias undulatas;
weakfish, Cynoscion regalis; spot, Leiostomus
xanthurus; silver perch, Bairdiella
chrysoura), ariids (hard-head and gafftopsail
catfish, Arius felis and Bagre marinus) and
clupeids (yellowfin and Atlantic menhaden, Brevoortia
smithi and Brevoortia tyrannus). Seasonal
shifts in species composition were attributed to
migration and various other marine and environmental
influences. Shrimp catches and bycatch mortality were
highest during the summer and fall and lowest in the
winter probably because of the higher water and air
temperature during the summer.
- Continental
Shelf Associates, Inc. 1992. Roller-frame trawl bait
shrimp fishery impacts on by-catch, seagrass meadows, and
habitat quality in Pine Island Sound, Florida. Draft
final report to Florida Department of Natural Resources.
3900 Commonwealth Blvd., Tallahassee, FL
32399.
- Of
the 57 species of fish caught as bycatch, the 4 most
abundant were pinfish (Lagodon rhomboides), silver
jenny (Eucinostomus gula), pigfish
(Orthopristis chrysoptera) and silver perch
(Bairdiella chrysoura). Floating pen mortality
experiments of by-caught fishes showed low mortality
among the fishes in both summer and winter because of a
combination of short tows, short culling times, and night
trawling. No statistically significant effect of
repetitive roller-frame trawling (multiple trawl passes)
on shoot density, blades/shoot, leaf blade length, or
leaf blade area was detected on designated turtle grass
sites, thus supporting the hypothesis that roller-frame
trawling did not physically or mechanically remove or
destroy seagrass.
- Fuls,
B. 1995. Assessment of composition and magnitude of
bycatch associated with the commercial shrimp trawling
industry in central lower Texas coastal bays during the
spring and fall Texas commercial bay-shrimp open seasons.
Final report to the Texas Parks and Wildlife Department.
4200 Smith School Road, Austin, TX 78744.
- Monitoring
three bays in lower Texas -- Aransas Bay, Corpus Christi
Bay, and lower Laguna Madre - this study reported that
bycatch was higher in the spring than in the fall.
Bycatch to shrimp ratios were 4:1 to 6.8:1 depending upon
season and area. Finfish to shrimp ratios were 1:1 to
5.1:1; again varying by season and area. Bycatch ratios
were highest in Corpus Christi Bay and lowest in Laguna
Madre. The report also noted that the quantity and
composition of the bycatch in this fishery-independent
survey was very different from concurrent
fishery-dependent surveys.
Bait
shrimp bycatch surveys (9.8 m trawl) in Lower Laguna
Madre during the spring of 1993 showed that four species
(lesser blue crab, Callinectes similis; Atlantic
croaker, Micropogonias undulatus; spot,
Leiostomus xanthurus; and sand seatrout,
Cynoscion arenarius) comprised 62 percent and 43
percent of the mean CPUE in number and weight,
respectively. The overall mean CPUE for bycatch was 2,966
organisms/h/net in number and 54.643 kg/h/net in weight.
In the fall, five species (sand seatrout; lesser blue
crab; spotfin mojara, Eucinostomus argenteus;
hardhead catfish, Arius felis; and Atlantic
Cutlassfish, Trichiurus lepturus) comprised 65
percent and 53 percent of the mean CPUE in number and
weight, respectively. The overall mean CPUE for bycatch
organisms was 1,597 organisms/h/net in number and 27.775
kg/h/net in weight.
- Gulf
of Mexico Fishery Management Council. 1980. Fishery
management plan and proposed regulations for the shrimp
fishery of the Gulf of Mexico, United States waters.
Federal Register 45:74178-74308.
- During
the early 1970's, the largest amount of licensed
recreational shrimpers (using 16 to 40 ft. nets) along
the Gulf coast resided in Louisiana (30,000) and caught
about 23,000,000 lb. of shrimp annually. Louisiana's
number of recreational shrimpers was followed by Texas
(>10,000), Alabama (5,100), Mississippi (>1,500),
and west Florida (>500) who caught approximately
900,000 lb., 204,000 lb., 290,000 lb., and 166,000 lb.,
respectively.
- Gulf
of Mexico Fishery Management Council. 1981. Draft fishery
management plan/ environmental impact statement and
regulatory analysis for groundfish in the Gulf of
Mexico.
- The
estimated recreational shrimping groundfish bycatch
during the 1970's was calculated to be 50,000 metric tons
(110,200,000 lbs.) annually for Alabama, Mississippi, and
Louisiana. The bycatch estimate was calculated by
multiplying the total annual recreational shrimp catch by
the average fish/shrimp ratio of commercial shrimp trawls
in inshore waters for the 1973-1977 period.
- Maharaj,
V., and C. Recksiek. 1991. The by-catch from the
artisanal shrimp trawl fishery, Gulf of Paria, Trinidad.
Mar. Fish. Rev. 53:10-15.
- Trinidad's
artisanal trawler catches (10 m trawl) of Penaeus
schmitti, P. subtillis, P. notialis, and
Xiphopenaues kroyeri, in the nearshore (<5 fm
isobath) of the heavily developed Gulf of Paria were
examined and showed annual weight ratio estimates of 9 kg
finfish : 1 kg shrimp and 14.7 kg bycatch : 1 kg shrimp
with monthly ratio estimates being the lowest (<10)
from late January to May (the dry season) and highest
during September to May (the wet season and peak time for
P. schmitti). Reported shrimp landings equaled
108,000 kg, while the total annual bycatch estimate was
1,594,000 kg (90 percent estimated to be discarded)
containing 974,000 kg of finfish (most caught August
-December) and 620,000 kg of crab.
- Wallace,
R.K., and C.L. Robinson. 1994. Bycatch and bycatch
reduction in recreational shrimping. Northeast Gulf
Science 13:139-144.
- Bycatch
from recreational shrimping was estimated from
fishery-independent trawling and through a survey of
licensed recreational shrimpers in Alabama. The mean fish
bycatch was 5.4 kg per 20-minute tow and contained 426
fish primarily from three families (Sciaenidae,
Engraulidae, Clupeidae). Based on the survey of
recreational effort, the total fish bycatch was estimated
at 603,000 kg or 47.6 million fish. Tests of two bycatch
reduction devices resulted in significant reduction for
the Florida Fish Eye, but no significant reduction for
the Fish Shooter.
From
the field sampling, bycatch to shrimp ratios were nearly
15:1 (range 1.2:1 to 93:1). Four hundred, seventy-four
surveys were returned (19.5 percent); usable surveys
indicated that, in 1990, recreational shrimpers averaged
5.6 trips, 4.3 tows per trip, and 38.2 minutes per tow
equaling approximately 40,000 net hours. Based on their
estimates of 16.2 kg of bycatch per net-hour, Alabama
recreational shrimping contributed to an estimated
648,000 kg of bycatch and 49,000 kg of shrimp for a 13:1
bycatch to shrimp ratio. Tests of bycatch reduction
devices included "fish shooter" (a slit in the bag), and
two sizes of "fisheyes" placed on the bottom of the bag.
The fisheyes in this configuration reduced fish, but lost
14 and 19 percent of the shrimp.
PURSE
SEINE FISHERIES
At the
present time, purse seine gear is used primarily to take
non-food finfish species in the Gulf of Mexico. Although a
small seasonal fishery exists in the eastern Gulf for
species harvested for direct consumption, the vast majority
of fish produced using this gear are industrial species such
as menhaden and baitfish such as round scad ("cigar
minnows"). In the past, purse seine gear was used to take
other species like red drum and mullet, but state and
federal regulations have effectively shut down these
fisheries. For example, four out of the five Gulf states
currently have a prohibition against the use of purse seine
gear in the striped mullet fishery. All of the Gulf states
have regulations regarding the amount of non-target species
which can be landed by a purse seine vessel (typically
expressed as a percentage of the catch by weight). The use
of purse seines for the taking of finfish other than
menhaden or herring-like species is prohibited outright in
some Gulf states. There is a relatively small-scale fishery
for finfish for direct consumption in federal waters
in the eastern Gulf. This fishery takes species such as
little tunny, blue runner, and crevalle jack. The menhaden
fishery is also subject to area and seasonal closures in all
Gulf states. With the exception of Florida, which has no
closed season, the menhaden season runs from the third
Monday in April to November 1 in the Gulf. There is also a
provision for a special bait season in Louisiana which can
extend the season until December 1 and allow for an opening
beginning April 1 subject to special permit
regulations.
The
menhaden fishery is one of the United States' oldest and
most valuable fisheries with landing dating to the late
1800's. Data for the fishery are sketchy prior to World War
II; thereafter, however, landings generally increased
through the mid 1980's as the industry grew. Although there
may be considerable annual fluctuations, Gulf landings
increased to a record of 2.2 billion pounds in 1984. This
figure amounted to 76 percent of U.S. menhaden and 29
percent of total U.S. landings of fish and shellfish (GSMFC,
1995).
Due to
the way the gear is operated, the menhaden purse seine
fishery is considered to be a relatively "clean" fishery
with little incidental harvest of non-target species.
Indeed, most early research into the effects of the fishery
on the ecosystem concentrated on predator-prey
relationships. Oviatt (1977) reported that sport fishermen
in the Narragansett Bay region or Rhode Island felt that
such a large portion of the biomass of menhaden was taken
that there was insufficient food for predator species.
However, calculations suggested that even when menhaden
abundances are so low that it is not commercially feasible
to catch them, they are still sufficiently abundant to be a
primary food source for predator fish. "Modern" studies of
menhaden fishery bycatch date back to the 1950's. Perhaps
due to the widely-publicized controversy regarding dolphin
interactions in the Pacific tuna purse seine fishery as well
as emerging user-group conflicts, the menhaden purse seine
fishery has been subject to more recent scrutiny regarding
bycatch.
Recent
Florida regulations regarding the use of commercial gear
have had a substantial impact on the eastern Gulf baitfish
fishery. Because this is primarily a shallow-water nearshore
fishery, and those waters are now closed to purse seine
gear, landings are down considerably. One of the largest
suppliers of round scad (Decapterus punctatus)
reports a drop in landings from one to 2 million pounds per
year to 15,000 pounds this year (Lancaster,
1996).
-
- Austin,
H., J. Kirkley, and J. Lucy. 1994. By-catch and the
fishery for Atlantic menhaden, Brevoortia tyrannus
in the mid-Atlantic Bight: An assessment of the nature
and extent of by-catch. Virginia Sea Grant Marine
Resource Advisory No. 53. College of William and Mary
School of Marine Science, Virginia Institute of Marine
Science Gloucester Point, Virginia 23062.
- This
study presents a framework for assessing the extent of
bycatch and an analysis of bycatch in the menhaden
fishery. A regulatory-enforcement type sampling scheme in
which all inspections were unannounced was designed and
sampling was conducted at the docks during off-loading
and on-board vessels during harvesting. Sampling was
conducted between June and November 1992.
A
total of 45 off-loadings and 43 at-sea sets were sampled.
Following industry practices , all counts of menhaden
caught or landed were measured in terms of standard fish
(1,000 standard fish weigh approximately 670 pounds). The
total number of menhaden off-loaded during dockside
sampling was 13.6 million standard fish; 2.5 million
standard menhaden were harvested during at-sea sampling.
Total bycatch observed in samples was 1,413 fish or
shellfish. Relative to the total harvest, bycatch was
estimated to account for 0.04097 percent and bycatch
rates had a seasonal component with higher rates (0.14
percent) in August and minimum rates (0.002 percent) in
September.
There
were substantial differences in percentage bycatch
observed between dockside and at-sea sampling with higher
percentages observed in at-sea samples. Thus, it was
concluded that dockside sampling is inadequate to
precisely determine the nature and extent of bycatch
because at-sea discards and associated mortality cannot
be determined. Bycatch of recreational species was
extremely low relative to the harvest of
menhaden.
- Condrey,
R. 1994. Bycatch in the U.S. Gulf of Mexico menhaden
fishery--results of onboard sampling conducted in the
1992 fishing season. Coastal Fisheries Institute,
Louisiana State University, Baton Rouge, Louisiana
70803-7503.
- Bycatch
in the U.S. Gulf of Mexico menhaden was sampled during
10, week-long onboard sampling trips made along the
Louisiana through Alabama coast during the 1992 fishing
season. Bycatch was estimated in two ways. By one method,
a long-handled net was used to sample the stream of fish
going through the chute into the hold. From one to five
such samples were taken per set, depending on the length
of the fish pumping operation. For each sample, the
weight and number of menhaden was recorded; as was the
identity, length frequency and total weight of each
bycatch species. These samples are termed "retained
bycatch." By the second method, the identity, estimated
length and fate of bycatch species which did not go
directly into the hold were recorded. These are termed
"released bycatch." The released bycatch were observed in
two areas. The first area was in association with the
net. Here the identity, fate, and estimated length of
fish which were enclosed by the net but not pumped into
the hose lowered into the hardened net were recorded. The
second area was the deck of the menhaden vessel. Bycatch
landed on the deck during normal pumping operations when
the chute of the large fish deflector was directed onto
the deck.
One
hundred and eighty-two (182) samples of the retained
bycatch were obtained from 49 sets. The intensity of
sampling per set ranged from one to five samples with a
mode of four samples per set. The weight of menhaden per
sample ranged from 10 to 42 pounds with a mode of 16
pounds and an arithmetic mean and standard deviation of
19.6 ± 5.5 pounds per set. The number of menhaden
per sample varied from 26 to 237 with an arithmetic mean
of 93.21 ± 43.30. The wide range in number of
menhaden per sample reflects the variation in individual
fish size in the three to four year classes which
comprise the fishery. The weight of total bycatch per
sample ranged from zero to four pounds per sample with a
mode of 0. The number of different species of bycatch
encountered per set ranged from zero to four with a mode
of zero. While 47 percent of the samples contained no
bycatch species, 77 percent contained zero or one
bycatch, and 93 percent contained zero to two bycatch
species. Atlantic croaker was by far the most frequently
observed bycatch, occurring in 30 percent of the samples.
Croaker were followed in frequency of occurrence in the
samples by Atlantic bumper (10 percent), silver seatrout
(9 percent), and gafftopsail catfish (7 percent).
Together these four species accounted for 56 percent of
the cumulative frequency of species
occurrences.
The
percent of the menhaden catch (by number) was computed as
the ratio of the weighted daily mean catch of bycatch per
sample to the average menhaden catch per sample, raised
to a percentage. Similar computations were performed to
determine the bycatch percentage by weight of the
menhaden catch. As such, retained bycatch were estimated
to account for 1 percent by number and 1.2 percent by
weight of the total catch.
The
most frequently encountered species in the released
bycatch were sharks (63 percent), followed by gafftopsail
catfish (61 percent) and crevalle jack (48 percent). Dead
release was high among the most abundant released bycatch
species. For example, 825 gafftopsail catfish were
observed. Of these, 57 percent were released dead. Of the
246 crevalle jack observed, 80 percent were released
dead. And of the 201 sharks observed, 50 percent were
released dead. Adding the released bycatch to the
retained bycatch for purposes of obtaining a bycatch to
menhaden ratio would not change the above figures of 1
percent by number and 1.2 percent by weight even if all
of the released bycatch were released dead. This paper
also has a good review of other related studies which are
summarized below. The author is critical of these
previous studies citing flaws in sampling techniques
which led to under-reporting of the released portion of
the bycatch. This critique also points to a lack of
statistical scrutiny of the data on the retained bycatch,
which has likely resulted in an over-estimation of its
magnitude. Despite the published reports of highly skewed
distributions, previous authors used simple arithmetic
means to extrapolate the bycatch samples to the entire
catch of the industry.
- Christmas,
J.Y., G. Gunter, and E.C. Whatley. 1960. Fishes taken in
the menhaden fishery of Alabama, Mississippi, and eastern
Louisiana. U.S. Fish and Wildlife Service Special
Scientific Report--Fisheries No. 339. 10 pp.
- Documents
a survey of menhaden vessels operating out of Mississippi
and fishing the waters of the Mississippi, Breton and
Chandeleur Sounds, as well as west of the Mississippi
River to Grand Isle in 1958. Though not detailed,
estimated total bycatch of the Gulf menhaden industry was
15 million pounds per year. This figure may be heavily
influenced by the accidental take of a single school of
striped mullet.
- Dunham,
F. 1972. Menhaden fishery investigations. In: A
study of commercially important estuarine-dependent
industrial fishes. Louisiana Wildlife and Fisheries
Commission Technical Bulletin 4:52-60.
- Dockside
sampling of menhaden bycatch in Louisiana was conducted
in 1971 and 1972. From 1971 results, a bycatch to
menhaden ratio of 0.05 percent by number was calculated.
In 1972, a total of 409 kg of menhaden was sampled. The
catch by weight consisted of 96 percent menhaden, 2
percent Atlantic thread herring and 2 percent other
species. Atlantic thread herring (which had not occurred
in the 1971 samples) should not be considered as bycatch,
since this is a highly desired fish in the fishery
because of its high oil yield.
- Guillory,
V., and G. Hutton. 1982. A survey of bycatch in the
Louisiana gulf menhaden fishery. Proceedings of the
Annual Conference of the Southeastern Association of Fish
and Wildlife Agencies 36:213-223.
- At-plant
sampling across the Louisiana coast for menhaden bycatch
was conducted. Eastern Louisiana had a higher bycatch
than did the central and western portion of the state.
The two-year average percentage by number was 4.6 percent
for eastern Louisiana, as compared to 1.1 percent and 1.3
percent for central and western Louisiana respectively.
By weight these percentages were 2.6 percent for eastern
Louisiana, as compared to 0.8 percent and 1.4 percent for
central and western Louisiana. Using an overall mean
percentage by weight ratio, the average annual bycatch
for 1970-1975 was estimated to be 14.6 million kg (32.2
million pounds).
- Knapp,
R.T. 1950. Menhaden utilization in relationship to the
conservation of food and game fishes of the Texas Gulf
Coast. Transactions of the American Fisheries Society
79:137-144.
- Onboard
sampling of the entire catch of 17 menhaden sets was made
off western Louisiana. A total of 1,574 fish other than
menhaden were taken in these 17 sets giving a bycatch to
menhaden ratio by number of 0.07 percent.
GILL
AND TRAMMEL NET FISHERIES
The use
of entanglement gear such as gillnets and trammel nets has
been and continues to be the subject of much controversy.
User group conflicts waged on the political front have
resulted in restrictions or prohibitions of the use of this
type of gear in all five Gulf states. Ironically, while
opponents of gill and trammel net use have cited bycatch as
one of the major problems in the fishery, very few
scientific studies exist to verify or refute this position.
Harrison (1996) provides the following summary of current
regulations regarding the use of gillnets on a
state-by-state basis:
Texas
was the first Gulf state to enact a gillnet ban. According
to the Texas Parks and Wildlife Department (TPWD), during
the late 1970's the state's red drum and seatrout
populations declined sharply due to harsh winters and
overfishing. To counter this trend, TPWD issued a
proclamation prohibiting gillnet use and sale of these fish
in 1981 over the objection of the commercial fishing
industry. TPWD banned all other types of commercial netting
for saltwater fish (excluding menhaden) in 1988. Since the
Texas gillnet ban, all four remaining Gulf states have
enacted various measures to restrict gillnetting.
Florida
enacted both a constitutional amendment and a statute
governing gillnet use which became effective on July 1,
1995. The amendment provides "no gillnets or other
entangling nets shall be used in Florida waters." The
statute provides in part "no person may take food fish
within or without the waters of this state with a purse
seine, purse gill net, or other net."
Alabama
has the distinction of being the only Gulf state where the
commercial and recreational fishermen sat down together and
worked out a compromise. Although over-fishing of striped
mullet was an issue in Alabama, the main concern was the
influx of Florida fishermen, ousted by their state's new
gillnet ban. The Alabama statute prohibits gillnets over
2,400 feet in length. In addition, the law imposes license
restrictions. An applicant must have purchased a license for
two years between 1989 and 1993. The applicant must also
have reported at least 50 percent of his gross income on an
Alabama tax return came from the capture and sale of seafood
two of the five years between 1989 and 1993. The law
requires higher fees for commercial gillnet permits from
non-residents.
In
Louisiana, the Coastal Conservation Association argued for
gillnet restrictions to protect against over-fishing of
marine stocks such as spotted seatrout and mullet. The
Louisiana legislature enacted gillnet restrictions as a
result. The main part of the law is the Louisiana Marine
Resources Conservation Act of 1995. The law establishes a
qualification system to determine which commercial fishermen
may receive a license to use gillnets. To qualify for a
license, an applicant must "provide positive proof that they
held a valid commercial gear license for gillnets during any
two years of the years 1995, 1994, and 1993." In addition,
an applicant must also show that they "derived more than 50
percent of their earned income from the capture and sale of
seafood species in at least two of the three years, 1995,
1994, or 1993." The law also restricts the length, mesh
size, and seasons in which nets can be used, as well as
their manner of use (e.g. setnets are prohibited and only
strike nets are allowed).
Mississippi
was the last Gulf state to address commercial gillnet
restrictions. On August 15, 1995, the Mississippi Commission
on Marine Resources passed an "emergency" regulation
restricting the issuance of gillnet licenses. The new
restriction provides for issuance of gillnet licenses only
to "individuals, firms or corporations that purchased
Mississippi gill and trammel net licenses during any license
year between May 1, 1990 and April 30, 1995." Contained in
Ordinance No. 5.013 adopted on November 16, 1996, is a
provision which stipulates in pertinent part that "On and
after January 1, 1997, all gill and trammel nets must be
constructed of an approved degradable material." Mississippi
also regulates where and when gill and trammel nets may be
used.
There
is also a fishery in federal waters for king and Spanish
mackerel using run-around gillnets. This fishery is
regulated using permit endorsements, trip limits and catch
quotas. The Gulf of Mexico is divided into seasonal
sub-zones for management purposes. As in the five Gulf
states, there are restrictions on net mesh size and size
limits on fish taken in the fishery. Mackerel are also taken
as a "bycatch" in the shark gillnet fishery in federal
waters. Consistent allocation overruns by both commercial
and recreational harvesters of king mackerel in the Gulf
will force a reduction in fishing effort in the near term.
The 1996-97 commercial season for Gulf group king mackerel
in the western zone closed in less than two months (July
1-August 26, 1996 ) after the quota for all methods
of fishing of 770,000 pounds was taken. Run-around gillnets
are also used to take dolphin but little production occurs
in Gulf waters.
-
- Acosta,
A.R., and R.S. Appeldoorn. 1995. Catching efficiency and
selectivity of gillnets and trammel nets in coral reefs
from southwestern Puerto Rico. Fisheries Research
22:175-196.
- A
comparative fishing experiment was conducted to
investigate the capture efficiency and selectivity of
bottom-set gillnets and trammel nets. Twelve gillnets and
trammel nets of different mesh size and hanging ratios
were fished from May 1990 to September 1991 in coral reef
and mangrove areas off La Parguera, Puerto Rico.
Significant differences in capture due to mesh size and
hanging ratio were observed. Largest catches in gillnets
were obtained by combination of high hanging ratio (1:3)
with large meshes (12.7 cm) or low hanging ratio (1:1)
with small meshes (7.6 cm). For trammel nets the largest
catches were obtained with low hanging ratio and large
meshes or high hanging ratio with small meshes. This
opposite interaction may arise from the different mode of
capture of these gears.
- Collins,
M.R., and T.I.J. Smith. 1994. Bycatch of Atlantic and
shortnose sturgeon in the South Carolina shad fishery.
(S-K annual report) Marine Resources Research Institute,
South Carolina Department of Natural Resources,
Charleston, South Carolina.
- The
sturgeon bycatch of the commercial American shad set
gillnet fishery in Winyah Bay, SC was documented during
the 1994 season. Examination of the bycatch from 2,561
net-hours (1 net-hour = 91.4 m of gillnet fished for 1
hour) of effort resulted in examination of 23 Atlantic
and four shortnose sturgeons, for a CPUE of 0.011
sturgeon/net-hour. Three Atlantic sturgeon were dead and
four were injured. Total fishing effort in the study area
during the 1994 season was estimated as 10,536 net-hours,
permitting an expansion of the bycatch to an estimated
115 sturgeons (85 percent Atlantic), of which it was
estimated that 12 died in the nets and 17 were released
with varying injuries.
- Hueter,
R.E. 1994. Bycatch and catch-release mortality of small
sharks in the Gulf coast nursery grounds of Tampa Bay and
Charlotte Harbor. (MARFIN NA17FF0378). Mote Marine
Laboratory, Sarasota, Florida.
- With
the cooperation of commercial fishermen working in the
Tampa Bay and Charlotte Harbor areas, fishery-dependent
surveys were conducted from November 1991 through August
1993 to document total catch in various fisheries, and
monitor bycatch of sharks, rays, bony fishes, and other
vertebrates in commercial operations. Total catches were
documented for commercial fishing trips in the following
fisheries: 1) purse seine fishery for baitfish in Tampa
Bay area; 2) roller frame trawl fishery for bait shrimp
in Pine Island Sound; 3) otter trawl fishery for food
shrimp in Charlotte Harbor; 4) gillnet fishery for
Spanish mackerel in Tampa Bay area; 5) gillnet fishery
for mullet in Tampa Bay and Charlotte Harbor; 6) gillnet
fishery for pompano in Tampa Bay and Charlotte Harbor; 7)
trammel net fishery for mullet in Tampa Bay; 8) trammel
net fishery for crevalle jack in Tampa Bay; and 9)
trammel net fishery for seatrout in Tampa Bay. Over the
course of the entire study, a total of 48 commercial gear
sets fishing for over 58.3 hours was documented.
Observed
shark bycatch in commercial fisheries was low, with 19
sharks of six species (juvenile blacktip, adult Florida
smoothhound, juvenile and adult bonnethead, juvenile
Atlantic sharpnose, juvenile lemon, and juvenile nurse)
documented. All but three of these sharks were caught in
gillnets targeting mackerel (an observed bycatch rate of
four sharks per set for this fishery). Estimated total
mortality was 54.8 percent of all juvenile and small
adult sharks caught. These mortality estimates apply
primarily to sharks caught in gill nets within the study
areas.
- Hueter,
R.E. 1994. Early life history and relative abundance of
blacktip and other coastal sharks in eastern Gulf of
Mexico nursery areas, including bycatch mortality of
sharks and associated fishes. (MARFIN NA57FF0034-01) Mote
Marine Laboratory, Sarasota, Florida.
- Although
it has a different title, this work is essentially an
extension of the above project into other geographic
areas for sampling to determine relative abundance and
develop a bioprofile of the shark species encountered.
This is ongoing work in which the investigator proposes
to get an estimate of bycatch mortality by using
commercial gillnet and longline to capture and tag
sharks. As in the above work, bycatch mortality estimates
will be inferred from tag returns.
- Kennedy,
S. 1994. Impact of nearshore gillnet fishery on marine
turtles on Florida's east coast--Report to the Florida
Marine Fisheries Commission. Florida Department of
Environmental Protection, Florida Marine Research
Institute, St. Petersburg, Florida.
- An
observer program was conducted jointly between the
National Marine Fisheries Service (NMFS) and Florida's
Department of Environmental Protection/Florida Marine
Research Institute (FMRI). A fishery-independent survey
was also conducted. Observers were posted on boats from
February 4, 1994, through May 5, 1994. Anecdotal
information suggested that the presence of observers can
affect the behavior of commercial or recreational
fishermen. In an attempt to identify the direction and
magnitude of those biases, a program to observe
commercial gillnet fishing from the beach was
implemented. Observers patrolled the beaches of Jupiter
Island and Hutchinson Island from April to May looking
for nearshore netting activity.
No
sea turtles were caught in any of the observer trips.
Twenty sea turtles were seen by NMFS observers in the
vicinity of the boats and two were seen by FMRI
observers. Median value of soak time observed from the
beach (15 minutes) was significantly larger than those
recorded from on-board observations (5.75 and 4.67
minutes). Between 27 percent and 40 percent of fishermen
who were unaware that they were being watched from the
beach did not abide by the zero soak time rule. Three sea
turtles were caught during the independent study
representing an overall 3.6 percent capture rate. Results
of the independent sampling show that when gillnets are
set as a stab net, soak time has a definite impact on the
catch of fish. Both the catch of fish and the time
necessary to retrieve the net were
increased.
FINFISH
TRAWLS
In the
past, trawl gear was used to take industrial bottomfish in
the Gulf of Mexico for the pet food industry, this fishery
has been all but phased out at the time of this writing. The
"croaker boats" used modified heavy-twine small-mesh shrimp
trawl designs developed in the northern Gulf to take species
suitable for meal or pet food production. As a result,
"bycatch" in this fishery is a manner of interpretation
since nearly everything was retained and used. Annual
production rates averaged about 45,000 metric tons, peaked
in 1974 and have been declining steadily since then.
Atlantic croaker, which is the target species because of its
desirability for canned pet food, is the predominant species
in landings and accounts for 69 percent by weight. Spot,
seatrouts (sand and silver) and cutlassfish are the other
primary species in the fishery. In 1963, the groundfish
fleet consisted of 50 vessels; today there are only two or
three boats in the fishery on a full-time basis.
Interestingly, although the fishery is prosecuted on
essentially the same grounds as the shrimp trawl fishery
using the same gear and incidental capture of sea turtles
was mentioned as a problem in the fishery (GMFMC, 1981),
TEDs were never mandated.
There
is a small-scale deep-water fishery using trawl gear for
butterfish in the Gulf. The fish are typically captured
using both bottom and midwater trawl in depths of over 50
fathoms. The small amount of incidental harvest associated
with this fishery is typically retained and sold as bait due
to the fact that no domestic or foreign markets have been
developed for species other than butterfish in the coastal
herring complex. Butterfish have a poorly developed swim
bladder and therefore have a unique signature on modern
color depth sounders. This helps to make this essentially a
single-species fishery.
Since
there has never been any perception of bycatch in the
finfish trawl fisheries operating in the Gulf of Mexico,
related studies are rare or non-existent. It may prove
beneficial to review some work done in other regions in the
event that marketing obstacles can be overcome for the
coastal herring complex and the vast resources (over five
million metric tons annual potential yield) begin to be
exploited.
-
- DeAlteris,
J.T., and D.L. Morse. 1994. The effects of sweep design
on the species selectivity of trawls in the silver hake
fishery of New England (S-K NA26FD0032).
- Trawl
nets in New England's small mesh fishery for silver hake
(Merluccius bilinearis) are highly non-selective
in the sizes and species of organisms they retain,
capturing not only saleable individuals of target
species, but juvenile individuals of target species, and
individuals of non-utilized species. This unusable catch
is returned to the water, but most discarded individuals
die as a result of the capture process or post-capture
predation.
In
this study, sea trials to evaluate the effects of trawl
sweep rigging on the retention of silver hake, other
gadoids, and flatfishes were performed, in the small mesh
silver hake fishery of New England. Experiments conducted
during November and December of 1992, in Cape Cod Bay,
MA, examined the selective effects of a raised fishing
line. Trials conducted in June and July of 1993 took
place near Block Island, RI, and evaluated designs
combining an elevated fishing line with a discontinuous
chain sweep. Fishing line heights ranged from 0.45 m to
0.9 m in the bosom of the trawl, with sections removed
from the sweep ranging from 2.1 to 4.6 m in length.
Designs were evaluated through alternate tow catch
comparisons, trawl geometry mensuration, and videographic
monitoring.
Wilcoxon
Signed-Ranks tests detected no significant reductions in
bycatch in the elevated fishing line experiments, at the
95 percent confidence level, while dramatic reductions in
bycatch occurred in the discontinuous sweep comparisons,
though loss of target species generally accompanies
bycatch loss. It is concluded that bottom disturbance by
the sweep is the primary stimulus controlling flatfish
escapement behavior in the trawl mouth.
-
- DeAlteris,
J.T., and K.M. Castro. 1992. Recent progress in the
development of selective trawls for demersal fisheries.
Department of Fisheries, Animal and Veterinary Science,
University of Rhode Island, Kingston, Rhode Island
02881.
-
- This
paper provides a good overview of work done to develop
species and size selective trawls for the northwest
Atlantic demersal fisheries. Sections address the
survival of escapees, fish size selectivity as a function
of mesh size and shape, and species selection through
mechanical size sorting and species-specific behavioral
patterns.
Codend
escapee survival appears to be reasonably high, and not
related to mesh shape. But for some species of actively
swimming fish, a square mesh shape provides a larger
opening that leads to a shorter escape time for the small
fish, thus presumably reducing the stress placed on the
fish during the capture/escape process. The
size-selection process occurs in the cod end; mesh size
in the body of the trawl has no selective
effect.
This
paper also contains the results of work done with the
Nordmore Grate in the northwest Atlantic shrimp fishery.
The bycatch of flatfish, cod and skates was nearly
eliminated with no shrimp catch reduction and an
improvement in the quality of the catch.
- Monaghan,
J.P. Jr., and J.L. Ross. 1995. Reduction of bycatch of
recreationally important fishes in North Carolina. North
Carolina Department of Environment, Health, and Natural
Resources, Division of Marine Fisheries, Morehead City,
NC.
- A
trouser trawl was used to examine the effectiveness of
large square and diamond mesh extensions and codends in
releasing small finfish from otter trawls used in the
nearshore ocean flynet fishery and the offshore black sea
bass and scup fisheries. Stretched mesh sizes of codends
and extensions tested in the nearshore work were 3-inch
square, 3.5-inch square, 4-inch square, 3-inch diamond,
and 3.5-inch diamond. Mesh sizes of extensions and
codends tested in the offshore work were 3-inch square,
3.5-inch square, 4-inch square, 3-inch diamond and 4-inch
diamond. Length frequencies of weakfish (Cynoscion
regalis), Atlantic croaker (Micropogonias
undulatus), southern kingfish (Menticirrhus
americanus), and spot (Leiostomus xanthurus)
were compared between the experimental and control
samples for the inshore work. Scup (Stenotomus
chrysops) and black sea bass (Centropristis
striata) lengths were compared in the offshore
work.
Smaller
weakfish were released by the large square and diamond
mesh gear for six of the 10 treatments tested. More large
southern kingfish and less small southern kingfish were
retained by the experimental side. Size distributions of
Atlantic croaker were similar between experimental and
control samples. The mean weight of the catch in the
experimental codends was 35 percent of the mean weight in
the control codend, in the nearshore segment of this
study. The mean catch weight of the experimental side was
47 percent of the control side for the offshore work. As
a result of the work done in this study, the North
Carolina Division of Marine Fisheries issued a
proclamation that required a 3-inch square or 3.5-inch
diamond mesh codend and a 3-inch square mesh extension in
flynets for the 1994-95 season.
- Robinson,
W.E., and H.A. Carr. 1993. Assessment of juvenile bycatch
survivability in the northeast fishing industry. (S-K
NA16FL0068). University of Massachusetts-Boston,
Environmental Sciences Program. Boston, MA
02125-3399.
- In
order to obtain quantitative data on the survival of the
deck discard of Atlantic cod (Gadus morhua) and
American plaice (Hippoglossoides platessoides),
two cruises were conducted aboard a commercial trawler.
Survival rates were determined by putting the "discarded"
fish in large cages and returning them to the tow depth
for a period of about 24 hours. The first cruise, in June
1991, resulted in overall survival rates of 13 percent
for cod and 44 percent for plaice. The second cruise, in
late April 1992, yielded survival rates of 51 percent for
cod and 66 percent for plaice. Measured blood parameters
for cod juvenile bycatch were elevated above control
values, even for fish measured within three minutes of
landing on deck. These data demonstrate that fish had
been considerably stressed prior to landing (either
during tow or haulback). Length of tow had no effect on
any of the measured blood parameters.
- Robinson,
W.E., H.A. Carr, and J. Harris. 1993. Assessment of
juvenile bycatch and cod-end survivability in the
northeast fishing industry--second year's study. (S-K
NA26FD0039). University of Massachusetts-Boston,
Environmental Sciences Program. Boston, MA
02125-3399.
- In
this extension of the above-referenced work, four cruises
were completed to assess the survival of the deck discard
of Atlantic cod (Gadus morhua), American plaice
(Hippoglossoides platessoides) and yellowtail
flounder (Pleuronectes ferrugineus). A spring
cruise in April 1992 resulted in overall survival rates
of 51 percent for cod, 66 percent for plaice, and 77
percent for yellowtail flounder. Two summer cruises
conducted in June 1991 and May-June 1992 produced
combined total survival rates of 9 percent for cod, 40
percent for plaice and 66 percent for yellowtail
flounder. One winter sampling cruise was conducted in
January-February 1993; cod survival was 36 percent;
plaice, 0 percent; and yellowtail flounder, 50 percent.
Primary factors that were determined to influence
survival of cod were air temperature, deck time, fish
length, tow duration and tow weight. Air temperature,
deck time, fish length and tow duration were most
critical to plaice survival. Tow duration and deck time
affect the survival of yellowtail flounder.
- Supan
J., and D. Bankston. 1988. Fish trawling in Louisiana
inshore waters. Louisiana Sea Grant College Program,
Center for Wetland Resources, Louisiana State University.
Baton Rouge, LA 70803-7507.
- The
purpose of this trawling project was to experiment with
different mesh sizes and trawl designs and compare
efficiency with the trawl developed by Noel Usannaz of
New Orleans for use in the Lake Borgne area of southeast
Louisiana. In 1983, Usannaz began using a 4-seam fish
trawl made primarily of 4-inch stretch mesh to catch
sheepshead and black drum. Experimental trawls included
trawls of the same design made of 5-inch and 6-inch
webbing, a bibbed trawl, a two-seam design, and the same
design with greater headrope flotation.
The
highest catches during the project were 20-40 pounds of
sheepshead and black drum, produced by 30-minute test
trawls. The test trawl catch commonly contained shrimp,
croakers, mullet, stingrays, menhaden, and other
herring-like species. The resulting fish trawl bycatch
consisted mainly of stingrays, mullet, and small
sheepshead. Very few, if any, shrimp, spotted seatrout,
red drum or other commercial species were caught by the
fish trawls, although these species were often found in
the test trawl catch. This is remarkably different from
shrimp trawling, making fish trawls extremely efficient
gear. Over the 12 trawling days, 28,040 pounds of salable
fish were caught, including test trawl catch. The total
sheepshead catch was 25,618 pounds and the black drum
catch was 2,422 pounds. At prices of $0.20/pound for
sheepshead and $0.60/pound for black drum, over $6,500
was earned, not including the sale of a small amount of
crab and mullet bycatch. Catching fish during colder
weather, when the inshore shrimp season is nearly over,
helped 12 vessel operators and their crews in Louisiana's
Lake Borgne area salvage a below-average shrimp trawling
season, allowing many of them economic survival through
the following winter.
RECREATIONAL
HOOK AND LINE FISHERIES
The
term "bycatch" is not usually associated with recreational
fisheries in the popular media but has been the growing
focus of researchers because of the magnitude of effort in
the fisheries. The operative definition of bycatch used here
and elsewhere is "those fish and shellfish which have no
market value, are damaged during harvest, or cannot be
legally sold or retained."
The
fishing event may cause either immediate mortality or the
potential for future mortality as a result of gear
interactions or handling. The release of undesired or
non-legal catch by recreational fishers certainly fits this
description of bycatch.
Studies
by Johnson and Griffith (1985), as well as many others have
shown the preferences recreational fishers have for certain
species over others in their catch are often based on flawed
or incomplete knowledge. Many species considered "trash
fish" are, in fact, quite edible and offer excellent sport
for recreational fishing. Further complicating the issue of
desirability are cultural and geographic differences in the
rating of recreationally caught species. For example,
smaller bluefish are considered relatively good table fare
on the East Coast of the U.S., but are typically discarded
as inedible in the northern Gulf of Mexico. Striped mullet
(the target of a recreational cast-net fishery) are prized
table fare in Florida, Alabama, and Mississippi, but are
seldom eaten in Louisiana and Texas. Size and creel limits
for many species contribute to a portion of the bycatch in
recreational fisheries in the Gulf of Mexico known as
"regulatory discards."
According
to National Marine Fisheries Service statistics, over 17
million saltwater fishing trips were taken by recreational
anglers in 1995 by residents in four of the five Gulf states
(data do not include Texas). Texas anglers spent 6.6 million
days fishing in saltwater in 1991 (Maharaj and Athey, 1996).
In 1995, recreational fishers in Alabama, Florida,
Mississippi, and Louisiana landed about 136 million fish
weighing over 73 million pounds. Recreational harvest of
edible finfish species roughly equals the commercial harvest
in the Gulf region. Thirty percent of all recreational
angling trips in the nation occurred in the Gulf and these
anglers landed 44 percent of all fish reported in 1995
(NMFS, 1996).
-
Campbell,
R.P., and P.C. Choucair. 1995. Characterization of
finfish bycatch of private-boat recreational anglers in
Texas marine waters (S-K Final Report NA37FD0084). Texas
Parks and Wildlife Department, 702 Navigation Circle,
Rockport, TX 78382.
- Data
were collected during the Texas Parks and Wildlife
Department's routine harvest monitoring program. On 50
percent of the surveys, bycatch tally cards were given to
anglers before the start of their fishing trip.
Interviews were conducted at the completion of each
fishing trip. On days when cards were given out (card
days), cards were collected at the completion of a
fishing trip and the information verified. On days when
cards were not given out (non-card days), anglers were
interviewed at the end of their trip and data were
recorded on a bycatch data sheet. Two independent bycatch
estimates were made using the same methodology employed
to generate recreational harvest estimates. Total numbers
of fish reported caught and released, and total number of
species reported were determined and compared between
card days and non-card days.
A
total of 719 survey days produced bycatch estimates of
3,105,100 fish for card days and 3,400,500 fish for
non-card days. Estimated landings of fish during the same
period were 1,380,200 fish. In addition, numbers of fish
reported released again showed no apparent differences
between card and non-card days for bays and passes or
Gulf areas. Landings to bycatch ratios were 1:2.25 for
card days and 1:2.46 for non-card days. Number of fish
reported released per interview in bays and passes was
12.14 for card days and 13.11 for non-card days. Ten
species of fish make up 96 percent of the total numbers
reported caught and released on both card and non-card
days. Spotted seatrout were the most reported caught and
released species on both card days (51 percent) and
non-card days (49 percent). This was followed by red drum
(39 percent and 38 percent, respectively) and hardhead
catfish (45 percent and 33 percent, respectively). Number
of fish reported released per interview from Gulf waters
was 8.47 on card days and 8.44 on non-card days. Ten
species of fish make up 85 percent of the total numbers
reported caught and released on card days and 82 percent
on non-card days. Red snapper were reported caught and
released the greatest number of times, 34 percent for
card days and 28 percent on non-card
days.
- Clark,
R.D. Jr. 1983. Potential effects of voluntary catch and
release of fish on recreational fisheries. North American
Journal of Fisheries Management
3:306-314.
- This
study examines how the release of legal fish might affect
a fishery. The classic yield-per-recruit model was
modified so that total mortality rate (Z) was partitioned
into three components: natural (M), fishing (F), and
hooking (H) mortality rates. Another parameter (p) was
used to represent the probability a legal fish was
released when captured, to modify the levels of fishing
and hooking mortality. Results indicated that the release
of legal-size fish reduced the total mortality rates of
the populations. As the release rates increased: 1) total
catch and catch of trophy fish increased (i.e. fish
harvested plus fish caught and released; 2) total harvest
decreased; and 3) harvest of trophy fish remained
relatively constant. The author states his belief that
the effects of voluntary release can be assumed
negligible if less than 10 percent of the legal fish
caught are released, but release rates higher than 10
percent change the interpretation of conventional creel
census estimates of catch and fishing mortality. The
actual catch will be higher than indicated by a survey of
fish in the creel, and the fishing mortality rates
computed from these data will underestimate the true
catch rate. Managers of sport fisheries need to estimate
the voluntary release rate, along with harvest and
fishing effort, if they want to assess a fishery
accurately.
- Edwards,
R.E., A.P. McAllister, and B.D. Fortune. 1989. Billfish
mortality and survivability. (Contract No. SA-88-07-MML).
Mote Marine Laboratory, 1600 Ken Thompson Parkway,
Sarasota, FL 34236.
- A
total of eight blue marlin were tagged with ultrasonic
transmitters, six by cooperating fishermen and two by the
tracking boat. Six of the eight were successfully
tracked. The fish ranged in size from 23 to 190 kg (50 to
420 pounds) and were caught on 50-130 pound test lines.
None were hooked deep and none were observed to be
bleeding at release. All six marlin were swimming
strongly and were judged to be surviving and in good
condition when tracking was terminated after periods
ranging from 2.2 to 6.4 hours.
- Edwards,
R.E. 1992. Tarpon release mortality assessment using
acoustic tracking. Final project report submitted to
Florida Department of Natural Resources. Mote Marine
Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL
34236.
- Tarpon
were tracked acoustically (ultrasonic transmitter tags)
after they were caught and released by anglers in Boca
Grande Pass, FL. A total of 26 of 27 tarpon were
surviving at the end tracking periods that averaged about
four hours and ranged up to 12.1 hours. Many tarpon
remained in the general area of the pass during the
tracking. Overall, the study documented the fact that
tarpon are relatively hardy and have a high probability
of surviving after being caught and released. It was
suggested that anglers can decrease tarpon release
mortality by minimizing handling.
- Edwards,
R.E. 1994. Development and evaluation of methods and
protocols for determining acute mortality of released red
drum, snook, Spanish mackerel and king mackerel. Mote
Marine Laboratory Technical Report No. 380. Mote Marine
Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL
34236.
- A
total of 24 snook ranging in size from 44 to 99 cm fork
length were caught and tagged with transmitters in or
near Gulf of Mexico waters. Of these, 23 were tracked for
periods ranging from two to 15 hours. All fish were
judged to be surviving at the end of the tracking
period.
A
total of 23 red drum were similarly caught and tagged
with transmitters from an area of shallow seagrass flats
along the western side of Sarasota Bay. All were found to
be moving and therefore surviving after periods ranging
from two to 19 hours.
A
total of 29 Spanish mackerel were caught in the nearshore
Gulf of Mexico, tagged and tracked for periods ranging up
to 5.2 hours. Three were judged not to survive, based on
their stationary position. During their tracking periods,
the surviving fish moved distances from 0.1 to 2 nautical
miles from their release points.
A
total of 20 king mackerel were caught using a variety of
angling techniques and were tagged and tracked for
periods up to 30 hours. Four fish died at or almost
immediately after release. One fish was lost due to
transmitter failure. Fourteen of the surviving fish were
tracked for 1.7 to 2.2 hours, at the end of which they
were 0.8 to 3.6 nautical miles from their release point.
Total distances covered after release were
typically much greater for both king and Spanish
mackerels.
- Edwards,
R.E. 1996. King mackerel hooking mortality assessment
(S-K NA37FD0087-01). Mote Marine Laboratory, 1600 Ken
Thompson Parkway, Sarasota, FL 34236.
- A
study was conducted to provide estimates of release
mortality rates of king mackerel, and to augment previous
estimates from a companion study of 18 percent mortality
within the first two hours after release (see Edwards,
1994 above). In the present study, release mortality
during the period from two to twenty-four hours after
release was assessed. King mackerel were caught using
normal angling techniques and gears, quickly tagged
non-invasively with small acoustic transmitters,
released, and followed for periods of up to 24 hours to
determine whether they survived (as indicated by their
continued movement) after being released.
A
total of 18 fish (17 king mackerel, one large Spanish
mackerel) were caught and tracked during the summers of
1994 and 1995. Three fish died within two hours, and two
were lost shortly after release due to problems with
electronic equipment. Thirteen fish were tracked for more
than two hours. Two tracks were abbreviated (3.4 and 10.4
hours) by storms. Of the remaining 11 fish, 9 were judged
to have been definitely surviving at the end of the
tracking, and 2 others were believed to have survived but
were thought to have shed their transmitter tags after
17.9 and 19.9 hours.
Combining
the results of this study with the previous companion
study provides an estimate of 18.2 percent for release
mortality within the first two hours and a 95 percent
confidence interval of 7 to 35.5 percent. Further
combining these results with similar estimates for
Spanish mackerel from the companion study provides an
estimate of 16.7 percent with a 95 percent confidence
interval of 8.6 to 27.9 percent. New information about
king mackerel movement patterns was obtained from the
paths of the tracked fish, which traveled at an average
speed of 1.1 knots and covered distances of up to 32
nautical miles. (Dr. Edwards has also compiled an
extensive bibliography of release mortality references
for both fresh and salt water studies, some of which are
reviewed here).
- Fable,
W.A. (Ongoing). Reef fish release mortality (1992-1994
progress reports). National Marine Fisheries Service
Panama City Laboratory, 3500 Delwood Beach Road, Panama
City, FL 32407.
- During
1992, six fishing trips with rod and reel provided 82
vermilion snapper caught from between 90 and 100 foot
depths. Fifty-three of these fish were then punctured to
relieve expanded gases from the swimbladder. Twenty of
these 53 were punctured with a knife, as a fisherman
might do, while the rest were punctured with a hypodermic
needle. Fifteen of the 82 fish died before they could be
released into holding pens at the Panama City Laboratory
docksite. All surviving vermilion snapper were kept in
pens for a minimum of 15 days to a maximum of 29 days. Of
the 67 fish released into pens, six died the first day,
and six more died over the duration of their captivity.
Fifty-five fish survived the entire period and were
released. This is an overall survival rate of 67
percent.
In
1993, 10 groups of ten fish were caught, with half the
fish having their swimbladders punctured. Fish were
alternately punctured or not punctured after a randomly
chosen start, whether they appeared to have an expanded
swimbladder or righting difficulties or not. The fish
were taken from 90-100 foot depths, returned to the
laboratory and kept in floating pens for 14 days. The
differences in overall survival between punctured and
unpunctured fish was significant at variation = .05 with
punctured fish exhibiting a higher survival rate. Overall
survival rate was 52 percent.
- Hegen,
H.E., G.E. Saul, and G.C. Matlock. 1984. Survival of
handled and tagged spotted seatrout held in wood and wire
cages. Management Data Series No. 61, Texas Parks and
Wildlife Department, 4200 Smith School Road, Austin, TX
78744.
- Spotted
seatrout (Cynoscion nebulosus) were captured by
hook-and-line in each of six Texas bay systems and placed
in wood cages during July-September 1982. During December
1982-April 1983, spotted seatrout were captured by
hook-and-line in each of seven bay systems and placed in
wire cages. Within each cage type, there were no
significant differences (P>0.05) in estimates of
survival of handled and tagged fish held for seven days.
Mean coastwide survival in wood cages ranged from 37.5
± 16 (SE) percent to 42.5 ± 12 percent.
Coastwide survival in wire cages ranged from 77.1 ±
13 percent to 85.7 ± 9 percent. Mean coastwide
survival rates adjusted for controls was 74 percent and
95 percent for wood and wire cages, respectively.
Computed survival in wood cages was probably less than in
wire cages because some fish escaped the wood cages and
were counted as mortalities and because wood cages were
less stable than wire.
- Jordan,
S.R., and A.G. Woodward. 1992. Survival of hook-caught
red drum. Proceedings of the Annual Conference of the
Southeastern Association of Fisheries and Wildlife
Agencies 46:337-344.
- Sub-legal
red drum (<355 mm) collected with angling gear during
1988 and 1989 were held in confinement to evaluate
post-hooking survival. During 1988, 217 fish were
collected by hook-and-line and 65 control fish were
collected with trammel and gill nets. In 1989, a total of
296 hook-caught and 103 net-caught red drum were used in
the study. Short-term post-hooking survival was 84
percent in both years. Gear and techniques favored by
Georgia anglers were used to collect experimental fish.
Single hooks of various materials in sizes 4 to 3/0 were
used on both float and bottom rigs deployed from small
boats. Live and dead penaeid shrimp were used most often
as bait. Experimental fish were examined, measured and
tagged. Hook type, size and location were recorded, and
the fish was temporarily placed in a nylon mesh holding
net until sampling was completed. Location of the hook
was defined as follows: maxilla, gill and esophagus. Most
fish were hooked in the maxilla area and 92 percent of
these individuals survived. Gill-hooked fish comprised 13
percent of the red drum collected and exhibited 68
percent survival. Only 10 percent were hooked in the
esophagus; however, these fish had the lowest survival
(47 percent). Red drum used as controls were collected
with monofilament gill and trammel nets in the same area
as the experimental fish. Fish were transported to the
holding site in an aerated 114-liter cooler. Both control
and hook-caught fish used in the study were held a
minimum of 14 days before release. Angler recapture rates
of marked hook-caught red drum were similar to those of
marked net-captured fish during 1988.
- Malchoff,
M. 1995. Effects of catch and release angling on
important northeast marine fishes: Mortality factors and
applications to recreational fisheries (S-K NA36FD0102).
New York Sea Grant Extension Program, 3059 Sound Avenue,
Riverhead, NY 11901.
- An
investigation into the level of post-angling,
catch-and-release mortality of bluefish (Pomatomus
saltatrix), striped bass (Morone saxatilis),
black seabass (Centropristis striata), scup
(Stenotomus chrysops), and weakfish (Cynoscion
regalis) in the New York marine recreational fishery
was undertaken. Forty angling trials aboard private,
charter and party boats, as well as shore-based were
conducted in which fish were caged following normal
catch-and-release procedures. After 72 hours, mortality
counts were made. Mean mortality estimates were 10.3
percent for bluefish, 5 percent for striped bass, and 9.9
percent for scup. Mortality for black seabass subject to
a depressurization change of three atmospheres was 21.8
percent. Because of the limited sample size, meaningful
estimates of weakfish mortality were not
obtained.
- Matlock,
G.C., L.W. McEachron, J.A. Dailey, P.A. Unger, and P.
Chai. 1993. Short-term hooking mortalities of red drums
and spotted seatrout caught on single-barb and treble
hooks. North American Journal of Fisheries Management
13:186-189.
- Short-term
(three days) hooking mortalities of red drums
(Sciaenops ocellatus) and spotted seatrout
(Cynoscion nebulosus) caught with single-barb
hooks were compared with hooking mortalities for those
caught with treble hooks in Texas bays in the summers of
1989 and 1990. Natural baits (primarily penaeid shrimp)
and artificial baits (spoons, worms, and fish-shaped
lures) were used with both hook types. Overall mortality
of 121 red drums was 4.1 percent at the end of three days
after capture, and there were no significant (P=0.67) red
drum mortality differences between hook types or bait
types. Mortality of 124 spotted seatrout was 7.3 percent
by three days after capture, and no significant (P=0.27)
differences between hook types or bait types were found.
Restricting anglers to one hook type (either single-barb
or treble hooks) would not reduce unintended fishing
mortality for either species.
- Muoneke,
M.I., and W.M. Childress. 1994. Hooking mortality: A
review for recreational fisheries. Reviews in Fisheries
Science 2(2):123-156.
- This
is an excellent review of a number studies on
catch-and-release (hooking) mortality gathered from the
existing fisheries literature and from a survey of
fisheries management in all 50 states, the U.S.
government, all Canadian provinces, and selected academic
and research institutions. Hooking mortality estimates
were identified for 32 taxa. Most studies dealt with
salmonids, centrarchids and percids. Within and among
species, differences in percent mortality were reported
in association with bait type (artificial vs. natural),
hook type (number of hooks, hook size, and barbs),
season/temperature, water depth (depressurization),
anatomical location of hook wound, and individual size.
Although most hooking mortalities occur within 24 hours,
the use of initial plus delayed mortality provides a more
complete estimate of mortality. Single hooks (especially
when used in conjunction with natural baits) resulted in
higher mortalities than treble hooks. Environmental
conditions (notably high water temperature and low
dissolved oxygen) are important to overall mortality
related to hooking, playing and handling. Mortalities
were highly variable; occasionally exceeding 30 percent
among red drum (Sciaenops ocellatus), smallmouth
bass (Micropterus dolomieu), largemouth bass
(Micropterus salmoides), cutthroat trout
(Oncorhynchus clarki), and catfishes
(Ictaluridae). Mortalities were occasionally found to
exceed 68 percent among spotted seatrout (Cynoscion
nebulosus), bluegills (Lepomis macrochirus),
crappies, (Pomoxis spp.), and striped bass
(Morone saxatilis).
(This
report is perhaps most valuable for its summary of other
studies and its extensive bibliography. A pertinent
excerpt for the Gulf of Mexico region is provided
below).
- Mortality
up to 55.6 percent was indicated for spotted seatrout
caught using natural baits on treble hooks as well as
artificial lures (Matlock and Dailey, 1981). In
another study, Matlock et al. (1993) reported
mortalities of 4.13 percent and 7.26 percent for red
drum and spotted seatrout, respectively, caught with
single and treble hooks on natural baits and
artificial lures. Hegen et al. (1983) reported 37
percent mortality for spotted seatrout caught using a
variety of gears. Martin et al. (1987) caught spotted
seatrout, red drum and black drum using baited circle
hooks on trotlines and attributed higher spotted
seatrout mortality to hooking in vital organs. Summer
mortality was 44.7 percent for red drum caught with
natural baits or artificial lures in a freshwater
reservoir (Childress, 1989a).
- Render
J.H., and C. A. Wilson. 1994. Hook-and-line mortality of
caught and released red snapper around oil and gas
platform structural habitat. Bulletin of Marine Science,
55(2-3): 1106-1111.
- The
study was conducted on an oil and gas platform
approximately 90 km south of Cameron, LA, in 21 m water
depth. Red snapper were caught by hook-and-line, treated
(control, gas bladder deflation, tagging, tagging with
deflation) and released into a vertical holding net (9 m
deep) for varying lengths of time (24, 30, 36, 48 h).
Results indicated an average mortality rate of 20 percent
at 21 m depth, with no significant difference between
treatments or time-in-net. There was a significant
difference in seasonal mortality, with higher mortalities
observed in summer versus fall. The long-term effect of
air bladder deflation on survival was investigated using
107 red snapper transferred to a large holding tank and
held for 30 to 40 days. All fish were tagged for
identification. Thirty-five of the red snapper had
deflated air bladders, while 72 were tagged only. Gas
bladder deflation did not significantly enhance survival
of released red snapper at 21 m.
- Render
J.H., and C. A. Wilson. 1993. Mortality rate and movement
of hook-and-line caught and released red snapper (MARFIN
NA90AAHMF762 Final Report) Coastal Fisheries Institute,
Louisiana State University, Baton Rouge, LA
70803.
- This
report more fully documents the work referenced above,
including two years of field work. Interestingly, this
report indicates higher seasonal mortalities in the fall
than in the summer (opposite of what was reported above)
and postulates that colder water temperatures during that
time of year may act as a stressor on red snapper. A
total of 345 red snapper were tested for the effects of
depth on mortality rates at five intervals ranging from
25 to 55+ m. The researchers also used ultrasonic tags as
an alternative method to track released red
snapper.
Results
from the variable depth tests did not show evident
differences in apparent survival due to deflation until
depths of approximately 30 to 40 m were reached. Based on
these results it did not appear that air bladder
deflation is an effective tool for enhancing survival of
released red snapper. The researchers also pointed to
some of the shortcomings of using ultrasonic telemetry to
locate and position individual red snapper around an oil
platform, including variable holding depth of the fish
and signal bounce caused by the platform structure. The
researchers postulated that the overall mortality rates
(approximately 20 percent) were conservative due to the
method used to obtain the estimates (i.e. releasing fish
into an open net system and tallying the number of red
snapper that were successful in
submerging).
- Saul,
G.E. 1992. Recreational fishery by-catch in the Galveston
Bay system. Publication GBNEP - 25. FTN Associates, Ltd.
7101 Highway 71 West, Suite 214, Austin, TX
78735.
- This
report does not reflect new research, but provides a
thorough review of existing research and data sets for
the Galveston Bay, Texas region. A preliminary estimate
of the recreational bycatch of sport fishermen was made
using a combination of data obtained from the National
Marine Fisheries Service's (NMFS) Marine Recreational
Fishery Statistics Survey (MRFSS) and routine creel
survey data provided by the Texas Parks and Wildlife
Department (TPWD). Data from the MRFSS included landings
of fish, determined to species by NMFS contractors, and
bycatch data based on fishermen recall during intercept
surveys. Data from TPWD included estimated annual
landings of fish by sport fishermen as determined by TPWD
fisheries professionals in intercept surveys.
Recreational
fishermen caught and released approximately two fish for
every fish landed. Because of the limited nature of the
data, estimates by species and year were not made. During
1979-1985, the years of concurrent data collection by
NMFS and TPWD, it was estimated that sport fishermen
caught and released between 1.2 and 3.5 million fish in
the Galveston Bay system. Approximately 5 percent of the
fish reported released were released dead. Available
literature on hooking and handling mortality suggests
that less than 15 percent of red drum released alive and
up to 30 percent of spotted seatrout released alive die
from injuries or stresses related to capture within seven
days of being hooked, handled and released.
TPWD
biologists used sport-fishing techniques to capture
spotted seatrout for tagging purposes. These "sport
fishermen" had a lower total bycatch ratio than
NMFS-surveyed fishermen, catching about one fish for
every fish tagged. The author states: "If it is assumed
that fishermen fishing specifically for spotted seatrout
would retain other desired species, the estimated bycatch
by these specialty fishermen would be even
less."
The
author states his belief that typical sampling methods,
such as intercept surveys conducted at the end of the
fishing trip, do not provide verifiable data. Studies
suggested to further explore recreational bycatch
included: 1) limiting bycatch recall studies to those
species under management regulations; 2) using
professionals (e.g. TPWD, NMFS, university or other
biologists) to emulate sport-fishermen; 3) using
volunteer fishermen to record catch information in
logbooks; and 4) conducting hooking and handling
mortality studies of selected species.
This
report also includes a listing of all the bycatch
literature holdings maintained by Natural Resources
Consultants, Inc. in their Seattle, WA library (Appendix
B-"Current North American and International Literature
Survey on Fisheries Bycatch"). One interesting fact is
apparent from reviewing this bibliography; although
fisheries bycatch is a world-wide issue encompassing many
fisheries and species, comparatively little work has been
done in the Gulf of Mexico region (with the possible
exception of the shrimp fishery) in addressing non-target
species impacts.
- Thomas,
R.G., J. Lightner, V. Hebert, and E. Lear. (in review).
Release mortality of red drum (Sciaenops
ocellatus) and spotted seatrout (Cynoscion
nebulosus) from four angling methods. Louisiana
Department of Wildlife and Fisheries, Lyle S. St. Amant
Marine Laboratory, P.O. Box 37, Grand Isle, LA
70358.
- A
hook-and-release mortality study of red drum and spotted
seatrout was conducted between May, 1993 and January 1995
at the Louisiana Wildlife and Fisheries, Lyle S. St.
Amant Marine Laboratory. Mortality rates for four
different common fishing methods were evaluated. Methods
used were: single hook with live bait (SHB), treble hook
with live bait (THB), single hook artificial lure (SHA),
and treble hook artificial lure (THA). All fishing was
done by boat within three miles of the laboratory. No
special care was taken in the unhooking and handling
process. Hooks were removed by hand in mouth-hooked fish,
with pliers in more deeply hooked fish, and were left in
place in the deepest hook sites. Fish were transported in
210-liter tanks with 32 liters per minute flow-through.
On return to the laboratory, fish were netted into 11
1,900-liter tanks located on a covered wharf, each with
38 liters per minute flow-through. Holding periods of
three days in summer and five days during colder months
were interspersed with seven-day holding periods to
assess delayed mortality. Water temperature, salinity and
dissolved oxygen concentration in the holding tanks
differed little from those parameters in the adjacent
bay. Total catch of spotted seatrout was 1,512; most were
taken in May-August, with live bait accounting for the
most fish. Total catch of red drum was 743, taken
primarily during July-February.
Overall
survival was 82.5 percent in seatrout and 97.3 percent in
red drum. Nearly all mortality in both species occurred
within the first 48 hours. Seatrout survival varied
widely between methods: 97 percent (THA), 91 percent
(SHA), 83 percent (THB), and 74 percent (SHB). Less
variation in survival was seen between red drum method
groups: 99 percent (SHA), 97 percent (THA), 96 percent
(SHB), and 94 percent (THB). Each method was numerically
well-represented in seatrout, but limited numbers of red
drum were taken with treble hooks. These results indicate
that far fewer red drum and spotted seatrout succumb
following hook-and-release than commonly believed, and
that the use of treble hooks doesn't induce excessive
mortality in released fish. The survival rate of released
red drum below the minimum size limit (406 mm) was not
significantly different from that of legal-sized fish (98
percent vs. 96 percent). Seatrout smaller than the 305 mm
limit were more likely to live (87 percent) than were
legal fish (81 percent).
- Virginia
Sea Grant. 1995. Release mortality in marine recreational
fisheries. Waterfront News Vol. 2, Nos. 1 & 2,
Spring/Summer 1995. Virginia Institute of Marine Science,
Gloucester Point, Virginia 23062.
- This
quarterly newsletter provides a good overall summary of a
recent conference entitled "Release Mortality in Marine
Recreational Fisheries: Current Research and Fishery
Management Implications." The conference was held in
Virginia Beach, Virginia on May 8-10, 1995. Following is
a list of summaries pertinent to species which can be
found in the Gulf of Mexico region:
-
- Field
and Laboratory Investigations into Striped Bass
Mortalities Following Angler Release was addressed
by Eric May of the Maryland Department of Natural
Resources. May undertook laboratory research to
determine the impact of temperature, salinity and fish
size on mortality. He found the most significant
factor affecting release mortality was temperature.
Larger fish (>21"), lower salinities (1.0 ppt) and
high temperatures (>21 degrees C) equal higher
mortality rates.
- Survival
Estimates for Demersal Reef Fishes Released by
Anglers was addressed by Mark Collins of the South
Carolina Marine Resources Institute. He sampled
various fish species caught in three depth zones, 21
m, 36 m and 46-54 m, off central South Carolina. The
fish were immediately observed for survival in holding
tanks, survivors placed in weighted mesh cages and
again observed for survival 24 hours later. Immediate
survival of the fish was determined by either their
ability to swim to the bottom of the holding tank
(possible survivors), or their floating on top of the
water (probable mortalities). Collins sampled more
than 15 species and found the "swim or float" method
of predicting survival to be valid for all species and
depths except black sea bass in 36 m (119 ft.). Pooled
estimates of survival for all species were
approximately 88 percent at 21 m, 81 percent at 36 m,
and 62 percent at 46-54 m. Survival differed by
species, but in general, release mortality increases
with increased depth of catch.
- Factors
Affecting Short and Long Term Hooking Mortality in
Virginia's Recreational Fishery for Summer
Flounder was the title of research results
presented by Jon Lucy and Tracy Holton of the VIMS Sea
Grant Marine Advisory Program. Fish caught with an
otter trawl are transported to a holding facility and
then caught with live bait on hook-and-line. Variables
being addressed are hook type, leaving hooks in place
in deeply hooked fish vs. removing them, crimping or
not crimping the hook barb, location of the hook
wound, the size of the fish, and the water
temperature. Results so far show an overall release
mortality of 18 percent. The most important variables
affecting mortality are location of hook wound and
water temperature. Of the fish that have been deeply
hooked or swallowed the hook, about 50 percent
died.
- The
use of ultrasonic tagging in real-world situations to
study release mortality was discussed by two
researchers, Randy Edwards (see above reference in
this category) and Phillip Bettoli. Edwards reported
survival rates for blue marlin, tarpon, red drum and
snook were between 96 percent and 100 percent. Spanish
and king mackerel had survival rates of 88 percent and
83 percent respectively. Bettoli reported that
mortality rates for striped bass in a Tennessee
reservoir were strongly influenced by air temperature
at time of capture. Mortality rates were approximately
15 percent in November and December, but went as high
as 67 percent in July and August. One surprising
result of the striped bass research was that the
condition of the fish when initially released (i.e.
"good" or "poor") was not an accurate indicator of
whether the fish lived or died.
- Wilson,
R.R. Jr., and K.M. Burns. 1996. Potential survival of
released groupers caught deeper than 40 m based on
shipboard and in-situ observations, and tag-recapture
data. Bulletin of Marine Science. 58(1):234-247.
(This study is reported under this heading
because of the way the subject fish were captured.
However, this work also applies to the commercial grouper
longline fishery in the western Gulf).
- In
this study, shipboard and in-situ observations were used
to determine the potential post-release survival rate of
groupers, chiefly red grouper (Epinephelus morio),
caught from between 44 and 75 m on the central west
Florida shelf. Potential survival rates were then further
evaluated in combination with data from a tag and
recapture study (3,818 releases) in the same area and
time period. Potential survival rates for released red
grouper and scamp (Mycteroperca phenax) caught
shallower than 44 m were very high (86 percent to 100
percent) for up to eight days following release.
Undersized grouper (<50.8 cm) caught from both
shallower and deeper than 44 m, then tagged and released,
were found to survive long enough to reach legal size.
For grouper caught deeper than 44 m, however,
tag/recapture data and in-situ observations indicate that
potential survival rates are too low (<33 percent) for
the 50.8 cm (20 inches) size rule to be effective in
increasing yield.
SUMMARY
AND RECOMMENDATIONS
One of
the most serious challenges in addressing Gulf of Mexico
fisheries bycatch is the lack of effective communication
among researchers, fishery managers, fishery user groups,
the environmental community and other stakeholders. This can
lead to the deliberate or inadvertent release of misleading
information. The new era of electronic communication offers
a great potential for the future, but currently is not
widely used by researchers and is still inaccessable to many
user groups and the general public. Electronic publication
with extensive keyword indices would also facilitate
information and data-sharing among those with access to
computer search capabilities. Research associated with
this document pointed to a serious lack of
computer-available reports. Relatedly, the authors also
found it somewhat vexing that the state of Texas was not
included in data generated by the Marine Recreational
Fisheries Statistics Survey for the Gulf of Mexico region.
Removing these types of bottlenecks which adversely affect
information sharing and distribution capabilities should be
of the highest priority.
Faced
with the fiscal reality of dwindling resources for
bycatch-related research, it is important for researchers to
concentrate their efforts on fisheries which generate the
most impacts on fish stocks. This can be determined by
amount of participation in the fishery, type of gear used,
landings data, relative impacts on non-target stocks, and
existing or incipient management regimes under which the
fisheries are prosecuted. Based on the studies reviewed
herein, three fisheries emerge as appropriate areas for more
intense study in the Gulf of Mexico region. They are, in no
particular order of significance: 1) the commercial shrimp
trawl fishery, due to the inherent non-selectivity of
small-mesh trawl gear; 2) the commercial hook-and-line reef
fish fishery, due to unanswered questions concerning
regulatory discards; and 3) the recreational hook-and-line
fishery, due to the vast number of participants and the
cumulative pressures on non-target species and non-legal
target species.
In the
Gulf of Mexico region, the majority of bycatch research
efforts to date have been directed at the commercial shrimp
trawl fishery. While species characterization and magnitude
surveys are current, and preliminary research into gear
development for bycatch reduction looks promising, much
remains to be done in the realm of information and
technology transfer to fishermen and other stakeholders such
as environmental groups. Further, a baseline must be
established from which to measure any bycatch reductions
attributable to management measures. Some existing research
indicates TEDs are also effective at reducing bycatch; will
gear-related reductions be measured against pre-TED or
post-TED levels? How will changes in effort in the fishery
in both the near term and the future be factored in to the
equation? What will change on an ecosystem-wide basis as
those species currently being removed by the fishery become
available elements of predator/prey relationships and enter
into the food chain at one level while simultaneously being
removed at other levels? Gear development, installation and
operation procedures will continue to evolve as the seafood
industry takes a more active role in BRD development in the
same manner as it did with TEDs. This information will need
to be shared on an industry-wide basis to mitigate any
potential adverse economic impact on shrimp
producers.
With
respect to the literature reviewed, the large variation in
mortalities within and between experiments suggests the need
for a standard experimental protocol for setting up,
conducting and monitoring survival experiments. This should
include some index of bycatch condition prior to capture so
that comparisons can be made between wild and experimental
organisms. Although injury type and location are recorded by
most authors, a classification system should be set up to
record the causes and severity of damages incurred. The same
approach should be taken to identify the range and severity
of stressors organisms may be subjected to during capture
and escape or release. Longer term studies should be aimed
at measuring the individual and cumulative effects of
stressors. Mortalities which occur after escape or release
have been attributed to stress associated with the capture
process. Regulatory measures to increase the escape of
bycatch such as the use of bycatch reduction devices (BRDs)
might also result in increased levels of mortality. Using
fishing gear selectivity as a fishery management tool
without adequate research into the condition of the
organisms escaping from fishing gear might not be the most
effective way to protect bycatch species (Chopin and
Arimoto, 1995).
With
the exception of the shrimp fishery, the other fisheries
examined had a small bycatch as a percentage of total catch,
and mortality associated with this bycatch (or regulatory
discard) was low compared to other sources of mortality.
There are some concerns centering on the accuracy of stock
assessment parameters currently being used, especially
regarding sources and magnitudes of mortality associated
with activities other than fishing (e.g. habitat loss,
pollution) for both targeted species and bycatch species.
The significance of bycatch mortality relative to natural
mortality is not well understood for most bycatch species.
It is apparent that, in many cases, the bycatch issue is
being driven by perception. Reducing bycatch is a desirable
goal, if for no other reason than maintaining the
sustainability of future harvests. However, it appears that
except in the case of a few species, there are no
documented negative impacts on finfish stocks because
of bycatch, and this point must be made clear. Those species
which are of concern in the Gulf of Mexico, such as
red snapper, king mackerel, and Spanish mackerel, are
harvested in several directed fisheries by a variety of user
groups, in addition to being taken as bycatch in the shrimp
trawl fishery. Undersized fish or fish released in excess of
bag and trip limits are also "bycatch" in the directed
fisheries. Future management measures and research should
address the broad spectrum of factors affecting the status
of fishery stocks, of which bycatch is but one component.
This type of ecosystem-based approach to research and
management is needed in the Gulf of Mexico because of the
enormous species diversity and broad spectrum of fisheries
in the region.
Additional
References:
Alabama
Department of Conservation and Natural Resources. 1995.
Commercial and recreational shrimping
regulations.
Arfman,
C. 1995. Billfish tournament deaths. Taranaki Polytechnic,
New Zealand. (Internet Posting,
c.arfman@taranaki.ac.nz).
Baxter,
B., and S. Keller (eds.). 1996. Solving bycatch:
considerations for today and tomorrow. Alaska Sea Grant
College Program Report No. 96-03. University of Alaska
Fairbanks.
Branstetter,
S. 1995. An industry workshop addressing bycatch issues in
southeastern U.S. fisheries: A report to the National Marine
Fisheries Service. Gulf & South Atlantic Fisheries
Development Foundation, Inc., Tampa, Florida.
Bull,
A.S. and J.J. Kendall, Jr. 1992. Estimation of fisheries
impacts due to underwater explosions used to sever and
salvage petroleum platforms. Minerals Management Service,
New Orleans, Louisiana.
Caillouet,
C.W. Jr., M.J. Duronslet, A.M. Landry, Jr., D.B. Revera,
D.J. Shaver, K.M. Stanley, R.W. Heinly, and E.K. Stabenau.
1991. Sea turtle stranding and shrimp fishing effort in the
northwestern Gulf of Mexico, 1986-89. Fish. Bull. U.S.
89:712-718.
Chopin,
F.S. and T. Arimoto. 1995. The condition of fish escaping
from fishing gears--a review. Fisheries Research
21:315-327.
Christmas,
J.Y., Etzold, D.J., McIlwain, T.D. and L.B. Simpson. (eds.)
1985. Marine fisheries initiative: Gulf of Mexico phase.
Gulf States Marine Fisheries Commission, Ocean Springs,
Mississippi.
Coleman,
E. 1995. A stitch in time...reducing bycatch now. Coast
& Sea (Winter 1995). Louisiana Sea Grant College
Program, Louisiana State University, Baton Rouge,
Louisiana.
Crouse,
D.T., Donnelly, M., Bean, M.J., Clark, A., Irvin, W.R. and
C.E. Williams. 1992. The TED experience: claims and reality.
(Internet abstract). Environmental Defense Fund, New York,
New York.
Dewees,
C.M. and E. Ueber. 1990. Effects of different fishery
management schemes on bycatch, joint catch, and discards:
summary of a national workshop. California Sea Grant
College, University of California, La Jolla,
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