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Modeling terminal-year fishing mortality rates in westernAtlantic bluefin tuna virtual population analyses

Published online by Cambridge University Press:  17 December 2012

John F. Walter  and
Clay E. Porch
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Abstract

Virtual population analysis requires information on the fishing mortality rate (orabundance) for one age group from each cohort. In many cases available data areinsufficient to estimate these rates for every age group and structural assumptions mustbe imposed to reduce the number of effective parameters. Past assessments of westernAtlantic bluefin tuna (Thunnus thynnus) have reduced the number ofparameters by assuming pre-specified values for the ratios of the fishing mortality rateson adjacent age groups. More recent bluefin tuna assessments have estimated terminalfishing mortality rates (F) on each age with a constraint that restrictschange from one year to the next. We explore the implications of these methods ofestimating terminal-year F through retrospective analyses of the 2006bluefin tuna assessment and through stochastic simulations. The use of pre-specifiedratios for F created strong retrospective biases and may have led tooverly optimistic projections. Constraining annual changes in the terminal-yearF appeared to mute retrospective patterns and resulted in abundanceprojections less prone to spurious initial leaps. Simulation results indicate that theconstraint improves estimation, particularly with moderate to low interannual changes inselectivity.

Keywords

Stock assessmentVirtual population analysisFishing mortality rateRetrospective patternsAge-based population modelThunnus thynnus
Type
Research Article
Information
Aquatic Living Resources , Volume 25 , Issue 4 , October 2012 , pp. 333 - 340
Copyright
© EDP Sciences, IFREMER, IRD 2012

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References

Anonymous, 1997, Report of the 1996 SCRS Bluefin Tuna Stock Assessment Session. Col.Vol. Sci. Pap. ICCAT 46(1), 1–186.
Anonymous, 1999, Report of the 1998 ICCAT SCRS Bluefin Tuna Stock Assessment Session. Col. Vol. Sci. Pap. ICCAT 49(2), 1–191.
Anonymous, 2001, Report of the 2000 ICCAT SCRS West Atlantic Bluefin Tuna Stock Assessment Session. Col. Vol. Sci. Pap. ICCAT 52 (3), 831–958.
Anonymous, 2003, Report of the 2002 Atlantic Bluefin Tuna Stock Assessment Session. Col. Vol. Sci. Pap. ICCAT 55(3), 710–937.
Anonymous, 2007, Report of the 2006 Atlantic Bluefin Tuna Stock Assessment Session. Col. Vol. Sci. Pap. ICCAT 60(3), 652–880.
Anonymous, 2009, Report of the 2008 Atlantic Bluefin Tuna Stock Assessment Session. Col. Vol. Sci. Pap. ICCAT 64(1), 1–352.
Anonymous, 2011, Report of the 2010 Atlantic Bluefin Tuna Stock Assessment Session. Col. Vol. Sci. Pap. ICCAT 66(2), 505–714.
Butterworth, D.S., Rademeyer, R.A. 2008, Statistical catch-at-age analysis vs. ADAPT-VPA : the case of Gulf of Maine cod. ICES J. Mar. Sci. 65, 1717–1732. CrossRefGoogle Scholar
Chen, Y., Jiao, Y., Sun, C.L., Chen, X., 2008, Calibrating virtual population analysis for fisheries stock assessment. Aquat. Living Resour. 21, 89–97. CrossRefGoogle Scholar
Doubleday, W.G., 1981, A method for estimating the abundance of survivors of an exploited fish population using commercial catch-at-age and research vessel abundance indices. Can. Spec. Publ. Fish. Aquat. Sci. 58, 164–178. Google Scholar
Fromentin, J.M., Powers, J., 2005, Atlantic bluefin tuna : population dynamics, ecology, fisheries and management. Fish Fish. 6, 281–306. CrossRefGoogle Scholar
Haddon M., 2001, Modelling and quantitative methods in fisheries. New York, NY. Chapman & Hall.
Gavaris S., Hazin F., Neilson J.N., Pallares P., Porch C., Restrepo V.R., Scott G., Shelton P., Wang Y. (eds.), 2008, Proc. The joint Canada-ICCAT 2008 workshop on the precautionary approach for western bluefin tuna, Halifax, Nova Scotia, 17–20 March, 2008.
Gavaris S., 1988, An adaptive framework for the estimation of population size. CAFSAC. Res. Doc. 88/29.
Gulland J.A., 1983, Fish stock assessment : a manual of basic methods. New York, NY Wiley.
Lassen H, Medley P., 2001,Virtual Population Analysis – A Practical Manual for Stock Assessment. FAO Fish. Tech. Pap. 400.
Megrey, B.A., 1989, Review and comparison of age-structured stock assessment models from theoretical and applied points of view. Am. Fish. Soc. Symp. 6, 8–48. Google Scholar
Mohn, R., 1999, The retrospective problem in sequential population analysis : An investigation using cod fishery and simulated data. ICES J. Mar. Sci, 56, 473–488. CrossRefGoogle Scholar
Parks, W.W., 1976, Cohort analysis, equilibrium yield per recruit analysis and predicted effects of minimum size limit regulation in the Atlantic bluefin tuna fisheries system. ICCAT Coll. Vol. Sci. Pap. 5, 313–331. Google Scholar
Parrack, M.L., 1986, A method of analyzing catches and abundance indices from a fishery. ICCAT Coll. Vol. Sci. Pap. 24, 209–221. Google Scholar
Patterson, K.R., Kirkwood, G.P., 1995, Comparative performance of ADAPT and Laurec-Shepherd methods for estimating fish population parameters and in stock management. ICES J. Mar. Sci. 52, 183–196. CrossRefGoogle Scholar
Pope, J.G, Shepherd, J.G., 1982, A simple method for the interpretation of catch at age data. ICES J. Mar. Sci. 40, 176–184. CrossRefGoogle Scholar
Pope, J.G., Shepherd, J.G., 1985, A comparison of the performance of various methods for tuning VPAs using effort data. ICES J. Mar. Sci. 42, 129–151. CrossRefGoogle Scholar
Pope, J.G., 1972, An investigation of the accuracy of virtual population analysis using cohort analysis. ICNAF Res. Bull. 9, 65–74. Google Scholar
Porch C.E., 2003, VPA-2BOX Version 3.01 Users Guide.NOAA Fisheries Southeast Fisheries Science Center Sustainable Fisheries Division Contribution SFD/2003-0004.
Shepherd, J.G., 1999, Extended survivors analysis : An improved method for the analysis of catch-at-age data and abundance indices. ICES J. Mar. Sci. 56, 584–591. CrossRefGoogle Scholar
Smith S.J.,Gavaris S., 1993, Evaluation the accuracy of projected catch estimates from sequential population analysis and trawl survey abundance estimates. In : Smith S.J., Hunt J.J., Rivard D. (Eds.) Risk evaluation and biological reference points for fisheries management, Can. Spec. Publ. Fish. Aquat. Sci. 120, 163–172.