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Management trade-offs between the directed and undirected fisheries of red snapper (Lutjanus campechanus) in the U.S. Gulf of Mexico

Michael J. Schirripa

Southeast Fisheries Science Center, Miami Laboratory, Sustainable Fisheries Division, 75 Virginia Beach Drive, Miami, FL 33149-1099,U.S.A.
Email: [email protected]

Abstract: Based on current assessments, the Gulf of Mexico red snapper stock is severely overfished, and catch allocations to the fishery are restricted. Confounding the issue of fishing mortality on this stock from directed fishing efforts is the incidental fishing mortality on juvenile red snapper from shrimp trawling. The offshore shrimp fishery exerts considerable mortality on age 0 and 1 red snapper in the form of discarded bycatch. The Gulf of Mexico Fisheries Management Council currently uses a minimum value for spawning potential ratio (SPR) of 20% as its management objective for red snapper, however, the future management goal will likely be based on maximum sustainable yield (MSY), or a proxy thereof. Values of MSY for the directed fishery were calculated for a range of bycatch mortalities and release mortalities while assuming fixed values for biological parameters. Values for MSY for the directed fishery differed for each level of bycatch mortality for the undirected fishery. More specifically, values of MSY for the directed fishery were systematically reduced by increases in bycatch mortality from the undirected fishery. Under the assumptions outlined for this analysis, it is highly unlikely that the resource could be simultaneously fished at FMSY and maintain a 20% SPR unless bycatch mortality can be reduced by approximately 90% or more. If approximately 50% to 60% bycatch reduction is the best that can be achieved by bycatch reduction devices (BRDs), and if the fishery is fished at FMSY, then the greatest SPR value that can likely be achieved will be approximately 10%. Of the three management options, FMSY, SPR equal to 20% and bycatch reduction of 50% to 60%, only two can be achieved simultaneously, but not all three.

1 INTRODUCTION

2 METHODS

R = P / (P + ß);

where R is recruitment in numbers of survivors at age 0, and P is parental fecundity. The inverse of the maximum number of recruits possible () was set at 4.09E-09, and the slope of the stock-recruitment curve at the origin (ß) was set at 1.74E+05. Natural mortality was 0.50 for age 0, 0.30 for age 1, and 0.10 for the remaining ages 2 to 50. Growth and fecundity were constant functions of age.

3 RESULTS

4 DISCUSSION

ACKNOWLEDGEMENTS

I thank Chris Legault for suggestions and help with calculations.

REFERENCES

BEVERTON, R.J.H., & HOLT, S.J. 1957. On the dynamics of exploited fish populations. Great Britain Ministry of Agriculture Fisheries and Food 19.

BRADLEY, E. & BRYAN, C.E. 1975. Life history and fishery of the red snapper (Lutjanus campechanus) in the north-western Gulf of Mexico: 1970-1974. Proceedings of the Gulf and Caribbean Fisheries Institute, 27: 77-106.

GOODYEAR, C.P. 1990. Status of red snapper stocks of the Gulf of Mexico report for 1990, National Marine Fisheries Service, Southeast Fisheries Center, Miami Laboratory, Miami CRDC89/90-05.

GOODYEAR, C.P. 1995. Red snapper in U.S. waters of the Gulf of Mexico, National Marine Fisheries Service, Southeast Fisheries Science Center, Miami Laboratory, Miami MIAC95/96-05.

MOE, M.A. 1963. A survey of offshore fishing in Florida. Professional Paper Series Marine Laboratory Florida, 4: 1-117. St. Petersburg, Florida.

RICKER, W.E. 1975. Computation and interpretation of biological statistics of fish populations. Fisheries Research Board of Canada Bulletin 191.

SCHIRRIPA, M.J. & LEGAULT, C.M. 1997. Status of the red snapper in U.S. waters of the Gulf of Mexico: updated through 1996. Southeast Fisheries Science Center, Miami Laboratory, Miami MIAC97/98-05.

SCHIRRIPA, M.J. 1998. Status of the red snapper in U.S. waters of the Gulf of Mexico: updated through 1997. NOAA/NMFS Sustainable Fisheries Division Contribution, SFD-97/98-30.

U.S. CONGRESS. 1990. Magnuson Fishery Conservation and Management Act (PL 94-265, as amended through November 28, 1990. Government Printing Office, Washington, D.C.

 

Figure 1a. Relative maximum sustainable yield (scaled to the maximum over all combinations) as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 0% release mortality for the directed fishery. Figure 1c. FMSY isopleths as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 0% release mortality for the directed fishery.

Figure 1b. Relative maximum sustainable yield (scaled to the maximum over all combinations) isopleths as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 0% release mortality for the directed fishery. Figure 1d. SPR isopleths as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 0% release mortality for the directed fishery

Figure 2a. Relative maximum sustainable yield (scaled to the maximum over all combinations) as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 20% release mortality for the directed fishery. Figure 2c. FMSY isopleths as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 20% release mortality for the directed fishery.

Figure 2b. Relative maximum sustainable yield (scaled to the maximum over all combinations) isopleths as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 20% release mortality for the directed fishery. Figure 2d. SPR isopleths as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 20% release mortality for the directed fishery.

Figure 3a. Relative maximum sustainable yield (scaled to the maximum over all combinations) as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 33% release mortality for the directed fishery. Figure 3c. FMSY isopleths as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 33% release mortality for the directed fishery.

Figure 3b. Relative maximum sustainable yield (scaled to the maximum over all combinations) isopleths as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 33% release mortality for the directed fishery. Figure 3d. SPR isopleths as a function of reductions in bycatch mortality and age at entry into the directed fishery assuming 33% release mortality for the directed fishery.

 

Evolution of the integrated scientific monitoring programme in Australia's South East Fishery

Ian A. Knuckey1, Chris Grieve2 and David C. Smith1

1 Marine and Freshwater Resources Institute, PO Box 114, Queenscliff, VIC 3225, Australia
Email: [email protected]
2 Australian Fisheries Management Authority, Box 7051, Canberra Mail Centre, ACT 2610, Australia.

Abstract: The South East Fishery is a complex, multi-species, multi-gear scalefish fishery which operates off south-eastern Australia. Monitoring of the fishery over the last 50 years has evolved from ad hoc research programmes conducted by several State and Commonwealth agencies to a statistically rigorous monitoring programme co-ordinated by the Australian Fisheries Management Authority (AFMA). The goals of this "Integrated Scientific Monitoring Programme" (ISMP) are well defined within AFMA's management objectives for the fishery. This paper describes the evolution of the ISMP and outlines the methods used to design the sampling strategy to achieve its objectives. Although voluntary, vessel participation rates in the ISMP are high, largely because information collected by the programme is not used for compliance purposes. Instead, the role of the ISMP is clearly defined as a means of collecting extensive information for use in stock assessment and management. The issues and implications of this type of approach to a monitoring programme are discussed.

1 INTRODUCTION

2 HISTORY OF MANAGEMENT IN THE SEF

2.1 Trawl Sector

2.2 Non-trawl sector

3 MANAGEMENT OBJECTIVES

  1. Implementing efficient and cost-effective fisheries management on behalf of the Commonwealth;
  2. Ensuring that the exploitation of fisheries resources and the carrying on of any related activities are conducted in a manner consistent with the principles of ecologically sustainable development and the exercise of the precautionary principle, in particular the need to have regard to the impact of fishing activities on non-target species and the long term sustainability of the marine environment;
  3. Maximising economic efficiency in the exploitation of fisheries resources;
  4. Ensuring accountability to the fishing industry and to the Australian community in AFMA's management of fisheries resources; and
  5. Achieving government targets in relation to the recovery of the costs of AFMA.

4 HISTORY OF MONITORING IN THE SEF

Table 1. Summary of monitoring and research projects undertaken in the SEF up to the commencement of the SMP in 1993.

Institution Period and Research Type Indicative references
Tasmanian Fisheries Port measuring 1978 - 1993

Fishery projects and trawl surveys 1980s

Wilson et al. (1984)

Lyle et al. (1991)

Lyle and Ford (1993)

Victorian Fisheries Port measuring 1981 - 1993

Fishery projects and trawl surveys 1977 - present

Gresik (1977)

Wankowski and Moulten (1986)

Smith et al. (1995)

NSW Fisheries Port measuring 1975 - 1991

Fishery projects and trawl surveys 1975 - present

Graham and Bell (1989)

Rowling (1990)

Kapala Cruise Reports

CSIRO Port measuring 1941 - 1967

Fishery projects and trawl surveys 1984 - present

Blackburn (1978)

Blaber et al. (1985)

Bulman et al. (1991)

Tilzey (1994)

CSIRO and TDPIF (1996)

Commonwealth Trawl surveys late 1970s

Logbook programme (Australian Fisheries Service and AFMA)

Anon. (1977, 1979)

5 ISMP DESIGN (SUMMARISED FROM SMITH ET AL. 1997)

  1. The total catch (retained and discarded) of quota species;
  2. The total catch (retained and discarded) of other species, and
  3. The size/age composition of the total catch (retained and discarded) for selected species.

5.1 Stratification

5.2 At-sea sampling

Discard rates for the non-trawl sector were not considered. Data were limited for this sector but discard rates were considered to be small. An independently funded pilot study has since been initiated to determine the extent to which at-sea sampling will be necessary in the non-trawl sector.

5.3 Sampling of length and age distributions

6 ISSUES AND FUTURE DIRECTIONS

6.1 Research and monitoring versus compliance

Figure 1. The geographical extent of Australia's Southeast fishery, showing the major fishing ports and the 14 strata highlighted in the design of the ISMP (Smith et al. 1997). The trawl and non-trawl sectors extend from the low water mark to the outer limit of the 200 N.M. Australian Fishing Zone (AFZ) off the states of South Australia (eastwards from Kangaroo Island for the trawl sector), Victoria and Tasmania. In New South Wales, the trawl sector extends from the 3 N.M. state limit to the outer limit of the AFZ south of Barrenjoey Point, and the non-trawl sector extends from outside 80 N.M. to the outer limit of the AFZ south of Fraser Island in Queensland.

Table 2. Stratification of the SEF based on gear type, main species caught, port group and size of landings. High catch vessels are those whose mean landing weight per trip over all fisheries is over 5 t. Low catch vessels are all others (after Smith et al. 1997).

Stratum
Code
Gear Port group Defining species
NSW INSH all O. Trawl NSW Spotted warehou, blue warehou, tiger flathead, jackass morwong, silver trevally, John dory and redfish
NSW OFFSH all O. Trawl NSW Blue grenadier (non-spawning), gemfish, ling, ocean perch, mirror dory
NSW RRP all O. Trawl NSW Royal red prawn
       
EDL DS all D. Seine EDEN LAKES School whiting, tiger flathead
EDL INSH hv O. Trawl, high catch vessels EDEN LAKES Spotted warehou, blue warehou, tiger flathead, jackass morwong, silver trevally, John dory and redfish
EDL INSH lv O. Trawl, low catch vessels EDEN LAKES Spotted warehou, blue warehou, tiger flathead, jackass morwong, silver trevally, John dory and redfish
EDL OFFSH all O. Trawl EDEN LAKES Blue grenadier (non-spawning), gemfish, ling, ocean perch, mirror dory
       
TAS ORO all O. Trawl TAS Orange roughy
TAS OTH all O. Trawl TAS All species excluding roughy and spawning grenadier
TAS SBG all O. Trawl TAS Blue grenadier (spawning)
       
SW OTH hv O. Trawl, high catch vessels SW All species excluding roughy and spawning grenadier
SW OTH lv O. Trawl, low catch vessels SW All species excluding roughy and spawning grenadier
SW ORO all O. Trawl SW Orange roughy
SW SBG all O. Trawl SW Blue grenadier (spawning)

Figure 2. Simulation modelling was used to assess the sampling intensity required to develop length distributions for each species with coefficients of variation (CVs) under 10%. The practical requirements of fish measuring determined that the target-sampling regime required 50 samples of approximately 100 fish per sample to achieve a CV of between 5 and 10%. Sampling regimes varied slightly for the different species (after Smith et al. 1997).

Table 3. Summary of scientific monitoring project data showing percentage discards by quota species and all other species combined. Source: SMP database. Note: excludes data from NSWFRI by-catch project.

Species Shots Sampled Retained catch (kg) Discarded catch (kg) Total catch (kg) Percentage discarded
Redfish 165 45370 88842 134212 66.2
Mirror dory 175 10403 11161 21564 51.76
Ocean perch 65 4298 2280 6578 34.66
Tiger flathead 216 76609 11271 87880 12.83
Blue warehou 170 41603 4914 46517 10.56
John dory 209 10677 751 11428 6.57
Spotted warehou 163 138366 7968 146344 5.45
Jackass morwong 179 41731 2364 44095 5.36
School whiting 66 58005 1644 59649 2.76
Silver trevally 120 15051 191 15242 1.25
Blue grenadier 111 138103 1634 139737 1.17
Ling 247 72596 636 73232 0.87
Orange roughy 34 201509 426 201935 0.21
Other species 359 310953 530499 841452 63.05

Figure 3. Simulation modelling was used to assess the sampling intensity required to develop age-length keys for each species with coefficients of variation (CVs) under 10%. The practical requirements of fish ageing determined that sampling was undertaken across all strata. The example shown is the mean weighted coefficient of variation (MWCV) for western gemfish against the sample size of the age-length key (after Smith et al. 1997).

6.2 Confidentiality

6.3 Collaboration

6.4 Insurance and safety

6.5 Training

6.6 Cost recovery

6.7 Future directions

  1. Endangered Species Protection Act 1992 (Commonwealth): A species can be listed as endangered or vulnerable (or other categories under the Act), in which case the process by which it is taken may be listed as a "key threatening process". This has occurred for turtles in the prawn-trawling fishery in northern Australia and has resulting in a recovery plan which is required under the Act, and for seabirds (mainly albatross spp.) in the tuna long-lining fishery, resulting in a threat abatement plan, also required under the Act.
  2. Wildlife Protection (Regulation of Exports and Imports) Act 1982 (Commonwealth): Schedule 4 lists species for which Environment Australia must issue a permit before export can occur. The Syngnathidae (seahorses, pipefish and seadragons), which can be taken as bycatch in trawling operations, are an example of such a group where permits of this nature are required.

ACKNOWLEDGEMENTS

REFERENCES

ANON. 1977. South-east Australian deepwater trawl survey. Fisheries Division Department of Primary Industry. Fisheries Report No 15. Canberra, Australia. 52pp.

ANON. 1979. South-east Australian deepwater trawl survey. Phase 2 Fisheries Division Department of Primary Industry. Fisheries Report No 16. Canberra, Australia. 40pp.

ANON. 1989. Management of the South East Trawl Fishery: A report of an Australian Fisheries Council Sub-Committee. Department of Primary Industries and Energy, Australia. 70pp.

ANON. 1998. Australia's Oceans Policy. Environment Australia. Commonwealth of Australia. 48 pp.

BLABER, S.J.M., KENCHINGTON, T.J. THRESHER, R.E., STANLEY, C., SHAKLEE, J.B. & MILTON, D.A. 1985. CSIRO study of blue grenadier Macruronus novaezelandiae. In: P. MILLINGTON, ed., Workshop on trawl fish resources working papers, Sydney, Australia, p. 1-22.

BLACKBURN, M. 1978. Changes in size composition, indicative of stock conditions in the New South Wales Trawl Fishery, from 1945/46 to 1966/67. CSIRO Division of Fisheries and Oceanography Report, 97, 76pp.

BULMAN, C.M., WAYTE, S.E. & ELLIOTT, N.G. 1991. Orange roughy surveys, 1988 and 1989: Abundance indices. CSIRO Mar. Lab. Rep. No. 215. 21pp

CHESSON, J. (ed.) 1997. The South East Fishery 1996, Fishery Assessment Report compiled by the South East Fishery Assessment Group: Australian Fisheries Management Authority. Canberra, Australia. 244pp.

CSIRO & TDPIF 1996. Orange roughy 1994, Stock Assessment Report, South East Fishery Assessment Group. Australian Fisheries Management Authority, Canberra, Australia, 204pp.

FAIRBRIDGE, W.S. 1948. The effect of the war on the East Australian Trawl Fishery. J. Council Sci. and Ind. Res., 21: 75-97.

GARVEY, J.R. 1996. Scientific Monitoring Project, South East Fishery. Final report to the Fisheries Resources Research Fund 1992 to 1995. Bureau of Research Sciences, Canberra, Australia. 71pp.

GARVEY, J.R. 1998. Interim Integrated Scientific Monitoring Programme 1996 and 1997. End of project report to the Australian Fisheries Management Authority. Bureau of Rural Sciences, Canberra, Australia, 72pp

GRAHAM, K.J., WINSTANLEY, R.H. & WILSON, M.A. 1982. Trawl and Danish seine fishery. Fishery Situation Report 9. South Eastern Fisheries Committee, CSIRO, Australia, 31 pp.

GRAHAM, K.J. & BELL, J.D. 1989. Collaborative study finds unexpected spawning population of orange roughy. Search, 20: 132-133.

GRESIK, J.H. 1977. Experimental deepwater bottom trawling off Portland, western Victoria. Fisheries and Wildlife Paper No 14, Ministry of Conservation, Victoria, Australia. 39pp.

KLAER, N.L. & TILZEY, R.D.J. 1994. The multispecies structure of the fishery. In: R.D.J. TILZEY, ed. The South East Fishery, Bureau of Resource Sciences, Canberra, Australia.

KNUCKEY, I.A. 1997. South East Fishery Integrated Scientific Monitoring Programme. Summary of 1996 port-based data collected from Victoria, South Australia and Tasmania. Report to the Australian Fisheries Management Authority, Canberra, Australia, 48pp.

KNUCKEY, I.A. & LIGGINS, G.W. 1998. Focussing on bycatch issues in Australia's South East Fishery. In: D.A. HANCOCK, ed. Establishing meaningful targets for bycatch reduction in Australian fisheries. Australian Society for Fish Biology Workshop, Hobart, Australia 24-25 September 1998.

KNUCKEY, I.A. & LIGGINS, G.W. (1999). Focussing on bycatch issues in Australia's South East Fishery. In: BUXTON, C.D. & EAYRS, S.E., eds., Establishing meaningful targets for bycatch reduction in Australian fisheries. Australian Society for Fish Biology Workshop Proceedings, Hobart, September 1998. p. 46-55.

LIGGINS, G.W. 1996. The interaction between fish trawling (in NSW) and other commercial and recreational fisheries. Final report to the Fisheries Research and Development Corporation. Project No. 92/79. 40pp + appendices.

LIGGINS, G.W. & KNUCKEY, I.A. (1999). Factors affecting discarding in the South East Fishery. In: BUXTON, C.D. & EAYRS, S.E., eds., Establishing meaningful targets for bycatch reduction in Australian fisheries. Australian Society for Fish Biology Workshop Proceedings, Hobart, September 1998. p.56-71.

LIGGINS, G.W., BRADLEY, M.J. & KENNELLY, S.J. 1997. Detection of bias in observer based estimates of retained and discarded catches from a multi-species trawl fishery. Fish. Res., 32: 133-147.

LYLE, J.M. & FORD, W.B. 1993. Review of trawl research 1979-1987, with summaries of biological information for the major species. Tas. Dept. Prim. Ind. Div. Sea Fish. Tech. Rep. No. 46. 169pp.

LYLE, J.M. 1994. Orange roughy Hoplostethus atlanticus. In: R.D.J TILZEY, ed. The South East Fishery. Bureau of Resource Sciences, Canberra, Australia, pp. 98 - 114.

LYLE, J.M., KITCHENER, J.A. & RILEY, S.P. 1991. An assessment of the orange roughy resource off the coast of Tasmania. Final Report to the Fisheries Research and Development Corporation, Project 87/65. Fisheries Research and Development Corporation, P.O. Box 222, Deakin West, ACT 2600, Australia. 129pp.

MORISON, A.K., ROBERTSON, S.G. & SMITH, D.C. 1998. An integrated system for production fish ageing: Image analysis and quality assurance. N. Amer. J. Fish. Man., 18: 587-598.

ROWLING, K.R. 1990. Changes in the stock composition and abundance of spawning gemfish Rexea solandri (Cuvier), Gempylidae, in south eastern Australian waters. Aust. J. mar. freshwater Res., 41, (1): 145-163.

ROWLING, K.R. 1994. Gemfish Rexea solandri. In: R.D.J. TILZEY, ed. The South East Fishery. Bureau of Resource Sciences, Canberra, Australia, p. 115-123.

SMITH, D.C., GILBERT, D.J., GASON, A. & KNUCKEY, I., 1997. Design of an Integrated Scientific Monitoring Programme for the South East Fishery. Report to the Australian Fisheries Management Authority, Box 7051 Canberra Mail Centre, ACT 2610, Australia. 50pp.

SMITH, D.C., HUBER, D., WOOLCOCK, J., WITHELL, A.F. & WILLIAMS, S. 1995. Western Bass Strait Trawl Fishery Assessment Programme. Final Report to the Fisheries Research and Development Corporation. 130pp + appendices.

SPORCIC, M.I. & KNUCKEY, I.A. 1998. South East Fishery Integrated Scientific Monitoring Programme: Operation and Procedures Manual. Report to the Australian Fisheries Management Authority, Box 7051 Canberra Mail Centre, ACT 2610, Australia. 58pp.

TILZEY, R.D.J. (ed.) 1994. The South East Fishery. Bureau of Resource Sciences, Canberra, Australia. 360pp.

TILZEY, R.D.J. (ed) 1998. The South East Fishery 1997. Fishery Assessment Report compiled by the South East Fishery Assessment Group. Australian Fisheries Management Authority, Canberra, Australia. 214pp.

WALKER, T.I., JOHNSTONE, D., BROWN, P. & MCLOUGHLIN, K. (eds.) 1998. The Southern Shark Fishery 1997. Fishery Assessment Report, Southern Shark Fishery Assessment Group. Australian Fisheries Management Authority, Canberra. 61pp.

WANKOWSKI, J.W.J. 1983. The Lakes Entrance Danish seine fishery for tiger flathead, school whiting and jackass morwong. Mar. Sci. Lab. Tech. Rep., No. 40. Marine Science Laboratories, Victoria, Australia. 31pp.

WANKOWSKI, J.W.J. & MOULTON, P.L. 1986. Distribution, abundance and biomass estimates of commercially important demersal fish species in eastern Bass Strait, Australia. Mar. Sci. Lab. Tech. Rep., No. 62. Marine Science Laboratories, Victoria, Australia.57 pp.

WILSON, M.A., EVANS, K.R. & CAMERON, M.R. 1984. A ground survey of the upper and mid-continental slope of southern Australia. (TFDA, Hobart, Tasmania.). 275pp.

The integration of information collected by fishery observers into the fisheries management process: A scientific perspective

David W. Kulka

Department of Fisheries and Oceans, P.O. Box 5667, St. John's NF, Canada A1C 5X1.
Email
: [email protected]

Abstract: Three case studies are used to illustrate the value of fishery observer data in the scientific management of commercial fisheries;

  1. Discards in the Canadian Atlantic shrimp fisheries. Information collected by observers was used to quantify the discard of groundfish species in the Newfoundland, Labrador and Davis Strait shrimp fisheries. This study illustrates how observer data was used in co-operation with industry to refine fishing and management strategies.
  2. Distribution of northern cod. Catch and effort data collected from the northern cod fishery integrated with research data were used to define population shifts and fishing effort changes during the last years of the fishery. This analysis helped to clarify mechanisms that affected the collapse of the stock.
  3. Emerging fishery for skate. The distribution of fishing effort for a new target species is examined in relation to the distribution of the stock. In the absence of data on fish size in catches, the fishing locations are compared with skate distributions derived from research surveys to determine the part of the population being exploited.

1 INTRODUCTION

2 CASE STUDY 1: DISCARDS IN THE CANADIAN ATLANTIC SHRIMP FISHERIES.

Figure 1. Observed gear deployment locations () for the northern shrimp fishery for the period 1988 to 1994 and the location of shrimp management area 6.

  1. Delineate areas of high bycatch used to define sub-areas where the use of the Nordmore grate was required;
  2. Examine the effect of the grate on groundfish bycatch; and
  3. Make informed decisions regarding management of the bycatch problem.

Figure 4. Labrador and Northeast Newfoundland Shelves and northern section of the Grand Bank comprising the extent of the northern cod stock. The boxes depict the four areas discussed in the text.

 

 

3 CASE STUDY 2: THE DISTRIBUTION OF NORTHERN COD

4 CASE STUDY 3: THE EMERGING FISHERY FOR SKATE IN CANADIAN ATLANTIC WATERS

Figure 5a. Distribution of the northern cod, 1988-1991. Upper panels show the autumn (fall) distribution based on research survey data. Middle panels show the winter distribution based on observer data and the lower panels show the spring distribution based on acoustic surveys. Lines depict acoustic tracks. Darker shades of gray denote more dense area of cod for all panels.

Figure 5b. Distribution of the northern cod, 1991-1994. Upper panels show the autumn (fall) distribution based on research survey data. Middle panels show the winter distribution based on observer data and lower panels show the spring distribution based on acoustic surveys. Lines depict acoustic tracks. Darker shades of gray denote more dense area of cod for all panels.

5 CONCLUSIONS

REFERENCES

ANON. 1994. Development of the skate fishery. Newfoundland Region Gear Conversion, Project Report, 194-259: 18 p.

ATKINSON, D.B. 1995. Skates in NAFO divisions 3LNO and subdivisions 3Ps: A preliminary examination. Department of Fisheries and Oceans Res. Doc. 95/26, Department of Fisheries and Oceans, Canada.

DAY, W.J. 1991. A marketing plan for the underutilised species Skate. Work report submitted to Carter, L., Faculty of Business Administration, Memorial University of Newfoundland, St. John's, Newfoundland, Canada, 33p.

HUETER, R.E. (1998) Science and management of shark fisheries. Fish. Res. Spec. Issue, 39 : 105-228.

JUNQUERA, S. & PAZ, X. 1998. Non-traditional resources: Skate fishery and survey results in Division 3NO. NAFO SCR Doc. 98/26, Ser. No. N3011. 6p.

KULKA, D.W. 1982. Estimates of discarding by the Newfoundland offshore fleet in 1981. CAFSAC Res. Doc. 82/34. 22p.

KULKA, D.W. 1984. Estimates of discarding by the Newfoundland offshore fleet in 1982. NAFO SCR Doc. 84/28, Ser. No. N809. 16p

KULKA D.W. 1985. Estimates of discarding by the Newfoundland offshore fleet in 1983. NAFO SCR Doc. 85/75, Ser. No. N1033. 19p

KULKA, D.W. 1986a. Estimates of discarding by the Newfoundland offshore fleet in 1984 with reference to trends over the past four years. NAFO SCR Doc. 86/12, Ser. No. N1120. 20p.

KULKA, D.W. 1986b. Estimates of discarding by the Newfoundland offshore fleet in 1985 with reference to trends over the past 5 years. NAFO SCR Doc. 86/95, Ser. No N1221. 20p.

KULKA, D.W. 1995. Bycatch of commercial groundfish species in the northern shrimp fisheries, 1980-1994 Department of Fisheries and Oceans Atl. Fish. Res. Doc.95/48, Department of Fisheries and Oceans, Canada. 16p.

KULKA, D. W. 1997. Discarding of cod (Gadus morhua) in the northern cod and northern shrimp directed trawl fisheries, 1980-94. NAFO Sci. Coun. Studies, 29: 67-79.

KULKA, D.W. 1998a. Spatial analysis of northern Atlantic cod distribution with respect to bottom temperature and estimation of biomass using potential mapping in SPANS. Department of Fisheries and Oceans Atl. Fish. Res. Doc. 98/13, Department of Fisheries and Oceans, Canada. 34p.

KULKA, D.W. 1998b SPANdex - SPANS geographic information system process manual for creation of biomass indices and distributions using potential mapping. Department of Fisheries and Oceans Atl. Fish. Res. Doc. 98/60, Department of Fisheries and Oceans, Canada. 28p

KULKA, D.W. & FIRTH, J.R. 1987. Observer Program Training Manual - Newfoundland Region. Can. Tech. Rpt. Fish. Aquat. Sci. No. 1355 (Revised). 197 p.

KULKA, D.W. & MOWBRAY, F.K. 1998. The status of thorny skate (Raja radiata), a non-traditional species in NAFO Divisions 3L, 3N, 3O and Subdivision 3Ps. Department of Fisheries and Oceans Atl. Fish. Res. Doc. 98/131, Department of Fisheries and Oceans, Canada. 70p.

LILLY, G.R., SHELTON, P.A., BRATTEY, J., CADIGAN, N., MURPHY, E.F., STANSBURY, D.E., DAVIS, M.B., KULKA, D.W. & MORGAN, M.J. 1998. An assessment of the cod stock in NAFO Divisions 2J+3KL. Department of Fisheries and Oceans Atl. Fish. Res. Doc. 98/15, Department of Fisheries and Oceans, Canada. 140p.

MAHARAJ, V. & RECKSIEK, C. 1991. The by-catch from the artisanal shrimp trawl fishery, Gulf of Paria, Trinidad. Inter research; Halstenbek (Germany). Mar. Fish. Rev., 53: 15p.

MOWBRAY, F.K. & KULKA, D.W. 1999. An overview of the Grand Banks skate fishery. In R. SHOTTON, ed. Case studies in the Management of Elasmobranch Fisheries. FAO Fish. Tech. Pap. FAO Fish. Tech. Pap. 378/1 47-73.

PARSONS, D.G. & VEITCH, P.J. 1997. Regional review of the status of northern shrimp (Pandalus borealis) resources in areas off Newfoundland and Labrador (Divisions 0B and 3K). Department of Fisheries and Oceans Atl. Fish. Res. Doc. 97/05,Department of Fisheries and Oceans, Canada. 38p.

ROSE, G.A. & KULKA, D.W. 1998. Hyper-aggregation of fish and fisheries: how CPUE increased as the northern cod declined. Can. J. Fish.Aquat. Sci. 56: 1-10.

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