Towards an ecosystem approach to fisheries management (EAFM) when trawl surveys provide the main source of information

Aquatic Living Resources

Volumn 22, Issue 2, 2009, Pages 243-254

  Cotter, John ^a   Petitgas, Pierre ^b   Abella, Alvaro ^c   Apostolaki, Panayiota ^a   Mesnil, Benoit ^b   Politou, Chrissi Yianna ^d   Rivoirard, Jacques ^e   Rochet, Marie Joëlle ^b   Spedicato, Maria Teresa ^f   Trenkel, Verena M ^b   Woillez, Mathieu ^e  

^a CENTRE FOR ENVIRONMENT   (United Kingdom)

^b IFREMER   (France)

^c ARPAT Agenzia Regionale per la Protezione Ambientale della Toscana   (Italy)

^d INSTITUTE OF OCEANOGRAPHY   (Greece)

^e CENTRE DE GÉOSCIENCES   (France)

^f COISPA Tecnologia and Ricerca ^*  (Italy)

Author keywords

Fisheries management; Fisheries independent assessment; Fishing effort indicator; Spatial indicator; State indicator; Survey based stock assessment; Trawl survey

Indexed keywords

ABUNDANCE; BIOINDICATOR; CATCH PER UNIT EFFORT; CATCHABILITY; FISHERY MANAGEMENT; MORTALITY; POPULATION ESTIMATION; POPULATION SIZE; STOCK ASSESSMENT; SUSTAINABILITY; TRAWLING;

EID: 67749127876     PISSN: 09907440     EISSN: 17652952     Source Type: Journal    
DOI: 10.1051/alr/2009025     Document Type: Article

References (115)

1. Abella A., Belluscio A., Bertrand J., Carbonara P., Giordano D., Sbrana M., Zamboni A., 1999, Use of MEDITS trawl survey data and commercial fleet information for the assessment of some Mediterranean demersal resources. Aquat. Living Resour. 12, 155-166.
2. Anonymous, 1986, Progress report 1985/1986 by ICES Statistician. Internat. Counc. Explor. Sea, Copenhagen, ICES CM 1986/D:19.
3. Anonymous, 2004, Report of the workshop on survey design and data analysis (WKSAD). Internat. Counc. Explor. Sea, ICES CM 2004/B:07, Ref. D.G. www.ices.dk/reports/FTC/2004/ WKSAD04.pdf
4. Anonymous, 2005, Report of the workshop on survey design and data analysis (WKSAD). Internat. Counc. Explor. Sea, Sète, France, ICES CM 2005/B:07. www.ices.dk/reports/FTC/2005/WKSAD05.pdf
5. Anonymous, 2006, Report of the study group on survey trawl standardisation (SGSTS). Internat. Counc. Explor. Sea, ICES CM 2006/FTC:05, www.ices.dk/reports/FTC/2005/SGSTS05.pdf
6. Apostolaki P., Hillary R., 2009, Harvest control rules in the context of fishery-independent management of fish stocks. Aquat. Living Resour. 22, 217-224.
7. Armstrong M.J., Payne A.I.L., Cotter A.J.R., 2008, Contributions of the fishing industry to research through partnerships. In: Payne A.I.L., Cotter A.J.R., Potter T. (Eds.) Advances in fisheries science 50 years on from Beverton and Holt. Oxford, Blackwell Publishing, pp. 63-84.
8. Beaugrand G., 2005, Monitoring pelagic ecosystems using plankton indicators. ICES J. Mar. Sci. 62, 333-338.
9. Beverton R.J.H., 1998, Fish, fact and fantasy. Rev. Fish Biol. Fish. 8, 229-249.
10. Buckland S.T., Andersen D.R., Burnham K.P., Laake J.L., Borchers D.L., Thomas L. (Eds.), 2004, Advanced distance sampling. Oxford University Press.
11. Caddy J.F., 2002, Limit reference points, traffic lights, and holistic approaches to fisheries management with minimal stock assessment input. Fish. Res. 56, 133-137.
12. Callaway R., Alsvåg J., de Boois I., Cotter J., Ford A., Hinz H., Jennings S., Kröncke I., Lancaster J., Piet G., Prince P., Ehrich S., 2002a, Diversity and community structure of epibenthic invertebrates and fish in the North Sea. ICES J. Mar. Sci. 59, 1199-1214.
13. Callaway R., Jennings S., Lancaster J., Cotter J., 2002b, Mesh-size matters in epibenthic surveys. J. Mar. Biol. Assoc. UK 82, 1-8.
14. Choi J.S., Frank K.T., Petrie B.D., Leggett W.C., 2005, Integrated assessment of a large marine ecosystem: a case study of the devolution of the eastern Scotian shelf, Canada. Oceanogr. Mar. Biol. Ann. Rev. 43, 47.
15. Cook R.M., 1997, Stock trends in six North Sea stocks as revealed by an analysis of research vessel surveys. ICES J. Mar. Sci. 54, 924-933.
16. Costello C., Gaines S.D., Lynham J., 2008, Can catch shares prevent fisheries collapse? Science 321, 1678-1681.
17. Cotter A.J.R. (Ed.) 2007, Manual of indicators and methods for assessing fish stocks using only fishery-independent, survey-based information. ICES CM 2007/O:27.
18. Cotter A., 2009, A selection of nonparametric statistical methods for assessing trends in trawl survey indicators as part of an ecosystem approach to fisheries management (EAFM). Aquat. Living Resour. 22, 173-185.
19. Cotter A.J.R., Burt L., Paxton C.G.M., Fernandez C., Buckland S.T., Pan J.-X., 2004, Are stock assessment methods too complicated? Fish Fish. 5, 235-254.
20. Cotter A.J.R., Mesnil B., Piet G., 2007, Estimating stock parameters from trawl CPUE-at-age series using year-class curves. ICES J. Mar. Sci. 64, 234-247.
21. Cotter A.J.R., Pilling G.M., 2007, Landings, logbooks and observer surveys: improving the protocols for sampling commercial fisheries. Fish Fish. 8, 123-152.
22. Cotter J., Mesnil B., Witthames P., Parker-Humphreys M., 2009, Notes on nine biological indicators estimable from trawl surveys with an illustrative assessment for North Sea cod. Aquat. Living Resour. 22, 135-153.
23. Daan N., Christensen V., Cury P.M. (Eds.), 2005, Introduction. Quantitative ecosystem indicators for fisheries management. ICES J. Mar. Sci. 62, 307-614.
24. Dambacher J.M., Gaughan D.J., Rochet M.-J., Rossignol P.A., Trenkel V.M., 2009, Qualitative modelling and indicators of exploited ecosystems. Fish Fish. 10, in press.
25. Daskalov G.M., 2008, Overfishing affects more than fish populations: a case of trophic cascades and regime shifts in the Black Sea. In: Payne A.I.L., Cotter A.J.R., Potter T. (Eds.) Advances in fisheries science 50 years on from Beverton and Holt. Oxford, Blackwell Publishing, pp. 418-433.
26. Daskalov G.M., Grishin A., Rodionov S., Mihneva V., 2007, Trophic cascades triggered by overfishing reveal possible mechanisms of ecosystem regime shifts. Proc. Nat. Acad. Sci. 104, 10518-10523.
27. De Oliveira J.A.A., Kell L.T., Punt A.E., RoelB.A., Butterworth D.S., 2008, Managing without best predictions: the management strategy evaluation framework. In: Payne A.I.L., Cotter J., Potter T. (Eds.) Advances in fisheries science 50 years on from Beverton and Holt. Oxford, Blackwell Publishing, pp. 104-134.
28. Demaré W., 2006, Fisheries-based management and advice in Europe. In: Motos L., Wilson D.C. (Eds.) The knowledge base for fisheries management. Amsterdam, Elsevier, pp. 295-305.
29. DFO, 2003, State of the eastern Scotian shelf ecosystem. Dept. of Fisheries and Oceans, DFO Can. Scient. Adv. Secr. Ecosystem status report, 2003/4.
30. EC, 2001a, Elements of a strategy for the integration of environmental protection requirements into the Common fisheries policy. Brussels, COM(2001) 143 final, http://eur-lex.europa.eu/ LexUriServ/LexUriServ.do?uri=COM:2001:0143: FIN:EN:PDF
31. EC, 2001b, Green paper on The future of the common fisheries policy. European Commission, Luxembourg, COM(2001) 135 final, http://ec.europa.eu/ fisheries/greenpaper/volume1-en.pdf
32. Ehrich S., Adlerstein S., Brockmann U., Floeter J., Garthe S., Hinz H., Kröncke I., Neumann H., Reiss H., Sell A.F., Stein M., Stelzenmuller V., Stransky C., Temming A., Wegner G., Zauke G.P., 2007, 20 years of the German small-scale bottom trawl survey (GSBTS): A review. Senck. Marit. 13.
33. Erzini K., Inejih C.A.O., Stobberup K.A., 2005, An application of two techniques for the analysis of short, multivariate non-stationary time-series of Mauritanian trawl survey data. ICES J. Mar. Sci. 62, 353-359.
34. Everson I., Bravington M., Goss C., 1996, A combined acoustic and trawl survey for efficiently estimating fish abundance. Fish. Res. 26, 75-91.
35. FAO, 2003, The ecosystem approach to fisheries. FAO Technical guidelines for responsible fisheries, 4.
36. Fletcher W.J., 2005, The application of qualitative risk assessment methodology to prioritize issues for fisheries management. ICES J. Mar. Sci. 62, 1576-1587.
37. Fulton E.A., Smith A.D.M., Johnson C.R., 2003, Effect of complexity on marine ecosystem models. Mar. Ecol. Prog. Ser. 253, 1-16.
38. Fulton E.A., Smith A.D.M., Punt A.E., 2005, Which ecological indicators can robustly detect effects of fishing? ICES J. Mar. Sci. 62, 540-551.
39. Garcia M., Cochrane K.L., 2005, Ecosystem approach to fisheries: a review of implementation guidelines. ICES J. Mar. Sci. 62, 311-318.
40. Gislason H., Pope J.G., Rice J.C., Daan N., 2008, Co-existence in North Sea fish communities: implications for growth and natural mortality. ICES J. Mar. Sci. 65, 514-530.
41. GjOslash;saeter H., Bogstad B., Tjelmeland S., 2002, Assessment methodology for Barents Sea capelin, Mallotus villosus (Muller). ICES J. Mar. Sci. 59, 1086-1095.
42. Greenstreet S.P.R., TuckI.D., Grewar G.N., Armstrong E., Reid D.G., Wright P.J., 1997, An assessment of the acoustic survey technique, RoxAnn, as a means of mapping seabed habitat. ICES J. Mar. Sci. 54, 939-959.
43. Grieve C., Short K., 2007, Implementation of ecosystem-based management in marine capture fisheries. Global marine programme, WWF International, Av. du Mont-Blanc, 1196 Gland, Switzerland. www.panda.org/marine
44. Hall S.J., Collie J.S., Duplisea D.E., Jennings S., Bravington M., Link J., 2006, A length-based multispecies model for evaluating community responses to fishing. Can. J. Fish. Aquat. Sci. 63, 1344.
45. Halliday R.G., Fanning L.P., Mohn R.K., 2001, Use of the traffic light method in fishery management planning. CSAS Res. Doc. 2001.
46. Hewitt D.A., Hoenig J.M., 2005, Comparison of two approaches for estimating natural mortality based on longevity. Fish. Bull. 103, 433-437.
47. Hiddink J.G., Jennings S., Kaiser M.J., 2006, Indicators of the ecological impact of bottom-trawl disturbance on seabed communities. Ecosystems 9, 1190.
48. Hillary R., 2009, An introduction to FLR fisheries simulation tools. Aquat. Living Resour. 22, 225-232.
49. Hutchings J.A., 1996, Spatial and temporal variation in the density of northern cod and a review of hypotheses for the stock's collapse. Can. J. Fish. Aquat. Sci. 53, 943-962.
50. Jackson J.B.C., Kirby M.X., Berger W.H., et al., 2001, Historical overfishing and the recent collapse of coastal ecosystems. Science 293, 629-638.
51. Jennings S., 2005, Indicators to support an ecosystem approach to fisheries. Fish Fish. 6, 212-232.
52. Jennings S., Kaiser M.J., 1998, The effects of fishing on marine ecosystems. Adv. Mar. Biol. 34, 201-352.
53. Kell L.T., Mosqueira I., Grosjean P., Fromentin J.M., Garcia D., Hillary R., Jardim E., Mardle S., Pastoors M., Poos J.J., Scott F., Scott R.D., 2007, FLR: an open-source framework for the evaluation and development of management strategies. ICES J. Mar. Sci. 64, 640-646.
54. Kell L.T., Pilling G.M., Kirkwood G.P., Pastoors M., Mesnil B., Korsbrekke K., Abaunza P., Aps R., Biseau A., Kunzlik P., Needle C., Roel B.A., Ulrich-Rescan C., 2005, An evaluation of the implicit management procedure used for some ICES round- fish stocks. ICES J. Mar. Sci. 62, 750-759.
55. Kimura D.K., Somerton D.A., 2006, Review of statistical aspects of survey sampling for marine fisheries. Rev. Fish. Sci. 14, 245-283.
56. Korsbrekke K., Mehl S., Nakken O., Pennington M., 2001, A survey- based assessment of the Northeast Arctic cod stock. ICES J. Mar. Sci. 58, 763-769.
57. Lack M., 2004, Ecosystem-based management in marine capture fisheries: a review of selected tools used in australian fisheries. WWF-Australia, PO Box 528, Sydney, NSW 2001 publications@wwf.org.au
58. Lapointe M.F., Peterman R.M., 1991, Spurious correlations between fish recruitment and environmental factors due to errors in the natural mortality rate used in virtual population analysis (VPA). ICES J. Mar. Sci. 48, 219-228.
59. Lembo G., Abella A., Fiorentino F., Martino S., Spedicato M.T., 2009, ALADYM: an age- and length-based single species simulator for exploring alternative management strategies. Aquat. Living Resour. 22, 233-241.
60. Link J.S., 2005, Translating ecosystem indicators into decision criteria. ICES J. Mar. Sci. 62, 569-576.
61. Link J.S., Brodziak J.K.T., Edwards S.F., Overholtz W.J., Mountain D.G., Jossi J.W., Smith T.D., Fogarty M.J., 2002, Marine ecosystem assessment in a fisheries management context. Can. J. Fish. Aquat. Sci. 59, 1429-1440.
62. Mackinson S., Freeman S., Flatt R., Meadows B., 2004, Improved acoustic surveys that save time and money: Integrating fisheries and ground- discrimination acoustic technologies. J. Exp. Mar. Biol. Ecol. 305, 129.
63. Mackinson S., van der Kooij J., 2006, Perceptions of fish distribution, abundance and behaviour: observations revealed by alternative survey strategies made by scientific and fishing vessels. Fish. Res. 81, 306.
64. Marchal P., Andersen B., Caillart B., Eigaard O., Guyader O., Hovgaard H., Iriondo A., Le Fur F., Sacchi J., Santurtun M., 2007, Impact of technological creep on fishing effort and fishing mortality, for a selection of European fleets. ICES J. Mar. Sci. 64, 192-209.
65. Marchal P., Ulrich C., Korsbrekke K., Pastoors M., Rackham B., 2003, Annual trends in catchability and fish stock assessments. Sci. Mar. 67 (Suppl. 1), 63-73.
66. McShane P.E., Broadhurst M.K., Williams A., 2007, Keeping watch on the unwatchable: technological solutions for the problems generated by ecosystem-based management. Fish Fish. 8, 153-161.
67. Mertz G., Myers R.A., 1997, Influence of errors in natural mortality estimates in cohort analysis. Can. J. Fish. Aquat. Sci. 54, 1608-1612.
68. Mesnil B., Cotter J., Fryer R.J., Needle C.L., Trenkel V.M., 2009, A review of fishery-independent assessment models, and initial evaluation based on simulated data. Aquat. Living Resour. 22, 207-216.
69. Mesnil B., Petitgas P., 2009, Detection of changes in time series of indicators using CUSUM control charts. Aquat. Living Resour. 22, 187-192.
70. Methratta E.T., Link J.S., 2006, Evaluation of quantitative indicators for marine fish communities. Ecol. Indicators 6, 575.
71. Mitson R.B., 1995, Underwater noise of research vessels - review and recommendations. ICES Coop. Res. Rep. 209.
72. Mitson R.B., Knudsen H.P., 2003, Causes and effects of underwater noise on fish abundance estimation. Aquat. Living Resour. 16, 255-263.
73. Motos L., Wilson D.C., 2006, The knowledge base for fisheries management. Elsevier.
74. MRAG, IFM, CEFAS, Tecnalia A., PoIEM, 2009, An analysis of existing rights based management (RBM) instruments in Member States and on setting up best practices in the EU. MRAG Ltd., London, FISH/2007/03.
75. Mullon C., Fréon P., Cury P., 2005, The dynamics of collapse in world fisheries. Fish Fish. 6, 111-120.
76. Myers R.A., Worm B., 2003, Rapid worldwide depletion of predatory fish communities. Nature 423, 280-283.
77. Nicholson M.D., Jennings S., 2004, Testing candidate indicators to support ecosystem-based management: the power of monitoring surveys to detect temporal trends in fish community metrics. ICES J. Mar. Sci. 61, 35-42.
78. Northridge S., Mackay A., 2006, United Kingdom progress report on cetacean research, April 2005 to May 2006, with statistical data for the calendar year 2005. Sea Mammal Res. Unit, University of St. Andrews, Scotland http://iwcoffice.org/-documents/sci-corri/2006progreports/SC-58-ProgRepUK.pdf
79. Pauly D., Christensen V., Guénette S., Pitcher T.J., Sumaila R., Walters C., Watson R., Zeller D., 2002, Towards sustainability in world fisheries. Nature 418, 689-695.
80. Petitgas P., 2007, Principal components analysis (PCA) and biological indicators. ICES CM 2007/O:27, pp. 122-125.
81. Petitgas P., 2009, The CUSUM out-of-control table to monitor changes in fish stock status using many indicators. Aquat. Living Resour. 22, 201-206.
82. Petitgas P., Poulard J.C., 2009, A multivariate indicator to monitor changes in spatial patterns of age-structured fish populations. Aquat. Living Resour. 22, 165-171.
83. Piet G., Jennings S., 2006, Response of potential fish community indicators to fishing. ICES J. Mar. Sci. 62, 214-225.
84. Piet G., Quirijns F.J., Robinson L., Greenstreet S.P.R., 2007, Potential pressure indicators for fishing, and their data requirements. ICES J. Mar. Sci. 64, 110-121.
85. Pope J.G., 1979, Population dynamics and management: current status and future trends. Invest. Pesq. 43, 199-221.
86. Porch C.E., Eklund A.M., Scott G.P., 2006, A catch-free stock assessment model with application to goliath grouper (Epinephelus itajara)off southern Florida. Fish. Bull. 104, 89-101.
87. Rees H.L., Boyd S.E., Schratzberger M., Murray L.A., 2006, Role of benthic indicators in regulating human activities at sea. Environ. Sci. Policy 9, 496-508.
88. Rees H.L., Ellis J.R., Hiscock K., Boyd S.E., Schratzberger M., 2008, Benthic communities, ecosystems and fisheries. In: Payne A.I.L., Cotter A.J.R., Potter T. (Eds.) Advances in fisheries science 50 years on from Beverton and Holt. Oxford, Blackwell Publishing.
89. Rice J.C., Rochet M.-J., 2005, A framework for selecting a suite of indicators for fisheries management. ICES J. Mar. Sci. 62, 516-527.
90. Rice J.C., Trujillo V., Jennings S., Hylland K., HagstromO., Astudillo A., Jensen J.N., 2005, Guidance on the application of the ecosystem approach to management of human activities in the European marine environment. ICES Coop. Res. Rep., 273, 22pp.
91. Rivard D., 1989, Overview of the systematic, structural, and sampling errors in cohort analysis. Am. Fish. Soc. Symp. 6, 49-65.
92. Rochet M.-J., Prigent M., Bertrand J.A., Carpentier A., Coppin F., Delpech J.-P., Fontenelle G., Foucher E., Mahe K., Rostiaux E., Trenkel V.M., 2008, Ecosystem trends: evidence for agreement between fishers' perceptions and scientific information. ICES J. Mar. Sci. 65, 1057-1068.
93. Rochet M.-J., Rice J.C., 2005, Do explicit criteria help in selecting indicators for ecosystem-based fisheries management? ICES J. Mar. Sci. 62, 528-539.
94. Rochet M.-J., Trenkel V.M., 2003, Which community indicators can measure the impact of fishing? A review and proposals. Can. J. Fish. Aquat. Sci. 60, 86-99.
95. Rochet M.-J., Trenkel V.M., 2009, Why and how could indicators be used in an ecosystem approach to fisheries management? In: Beamish R.J., Rothschild B.J. (Eds.) The future of fisheries science in North America. Springer, pp. 209-226.
96. Rose G.A., KulkaD.W., 1999, Hyperaggregation of fish and fisheries: how catch-per-unit-effort increased as the northern cod (Gadus morhua) declined. Can. J. Fish. Aquat. Sci. 56, 118-127.
97. Rotherham D., Underwood A.J., Chapman M.G., Gray C.A., 2007, A strategy for developing scientific sampling tools for fishery- independent surveys of estuarine fish in New South Wales, Australia. ICES J. Mar. Sci. 64, 1512-1516.
98. Seijo J.C., Caddy J.F., 2000, Uncertainty in bio-economic reference points and indicators of marine fisheries. Mar. Freshw. Res. 51.
99. Shin Y.-J., Rochet M.-J., Jennings S., Field J.G., Gislason H., 2005, Using size-based indicators to evaluate the ecosystem effects of fishing. ICES J. Mar. Sci. 62, 384-396.
100. Spedicato M.T., Woillez M., Rivoirard J., Petitgas P., Carbonara P., Lembo G., 2007, Usefulness of the spatial indices to define the distribution pattern of key life stages: an application to the red mullet (Mullus barbatus) population in the south Tyrrhenian Sea. ICES CM 2007/O.
101. Tasker M.L., Hope Jones P., Dixon T., Blake B.F., 1984, Counting seabirds at sea from ships: a review of methods employed and a suggestion for a standardized approach. The Auk 101, 567-577.
102. Travers M., Shin Y.J., Shannon L., Cury P., 2006, Simulating and testing the sensitivity of ecosystem-based indicators to fishing in the southern Benguela ecosystem. Can. J. Fish. Aquat. Sci. 63, 943-956.
103. Trenkel V.M., 2008, A two-stage biomass random effects model for stock assessment without catches: what can be estimated using only biomass survey indices? Can. J. Fish. Aquat. Sci. 65, 1024-1035.
104. Trenkel V.M., Cotter A.J.R., 2009, Choosing survey time series for populations as part of an ecosystem approach to fishery management. Aquat. Living Resour. 22, 121-126.
105. Trenkel V.M., Pinnegar J.K., Rochet M.-J., Rackham B., 2004, Different survey designs provide similar pictures of community structure but not of individual fish populations. ICES J. Mar. Sci. 61, 351-362.
106. Trenkel V.M., Rochet M.-J., 2008, Intersection-union tests for characterising recent changes in smoothed indicator time series. Ecol. Indicators 9, 732-739.
107. Trenkel V.M., Rochet M.-J., Mesnil B., 2007a, Combining trend signals using a cause-effects table. ICES CM 2007/0:27 FISBOAT final report, pp. sect. 5.5.1.
108. Trenkel V.M., Rochet M.J., Mesnil B., 2007b, From model-based prescriptive advice to indicator-based interactive advice. ICES J. Mar. Sci. 64, 768-774.
109. Tuck I.D., Chapman C.J., Atkinson R.J.A., Bailey N., Smith R.S.M., 1997, A comparison of methods for stock assessment of the Norway lobster, Nephrops norvegicus, in the Firth of Clyde. Fish. Res. 32, 89-100.
110. Vetter E.F., 1988, Estimation of natural mortality in fish stocks: a review. Fish. Bull. 86, 25-43.
111. Walters C., 1986, Adaptive management of renewable resources. MacMillan Publishing Co., New York.
112. Ward T., Tarte D., Hegerl E., Short K., 2006, Ecosystem-based management of marine fisheries-policy proposals and operational guidance for ecosystem-based management of marine capture fisheries. World Wide Fund for Nature Australia www.panda.org
113. Woillez M., Poulard J.C., Rivoirard J., Petitgas P., Bez N., 2007, Indices for capturing spatial patterns and their evolution in time, with application to European hake (Merluccius merluccius)in the Bay of Biscay. ICES J. Mar. Sci. 64, 537-550.
114. Woillez M., Rivoirard J., Petigas P., 2009a, Notes on survey-based spatial indicators for monitoring fish populations. Aquat. Living Resour. 22, 155-164.
115. Woillez M., Rivoirard J., Petitgas P., 2009b, Using min/max autocorrelation factors of survey-based indicators to follow the evolution of fish stocks in time. Aquat. Living Resour. 22, 193-200.