Size-Selective Harvesting and Age-At-Maturity II: Real Populations and Management Options

  • T. K. Stokes
  • S. P. Elythe
Part of the Lecture Notes in Biomathematics book series (LNBM, volume 99)


Parameters for a simple stage-structured harvesting model are derived for five North Sea demersal fish stocks. The parameters are used to generate contour plots of fitness and yield on axes of size-at-maturity Vs size-at-first-capture, and age-at-maturity Vs age-at-first-capture. Such graphs are used qualitatively to assess possible changes in the exploited populations that might result from management actions such as altering mesh size (and hence size-at-capture) and/or harvesting rate.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Anon 1990a. Report of the North Sea Roundfish Working Group. I.C.E.S. C.M./Assess: 7.Google Scholar
  2. Anon 1990b. Report of the North Sea Flatfish Working Group. I.C.E.S. C.M./Assess: 6.Google Scholar
  3. Anon 1990c. 16th. Report of the Scientific and Technical Committee for Fisheries. Commission of the European Communities SEC 90 1327.Google Scholar
  4. Anon 1990d. Report of the I.C.E.S. Advisory Committee on Fisheries Management. I.C.E.S. Co-operative Research Report no. 173.Google Scholar
  5. Anon 1991. 17th. Report of the Scientific and Technical Committee for Fisheries. Commission of the European Communities SEC 90 2173.Google Scholar
  6. Beverton, R.J.H. and S.J. Holt. 1957. On the Dynamics of Exploited Fish populations. Fisheries Investigations London. Series II 19: 1–533.Google Scholar
  7. Blythe, S.P. and T.K. Stokes. 1991. Some consequences of size-selective harvesting on fitness and on yield. IMA Journal of Mathematics Applied in Medicine and Biology 7: 41–53.CrossRefGoogle Scholar
  8. Daan, N. 1975. Consumption and production in North Sea cod (Gadus morhua): an assessment of the ecological status of the stock. Netherlands Journal of Sea Research 9: 24–55.CrossRefGoogle Scholar
  9. Gulland, J.A. 1965. Estimation of mortality rates. Annex to Arctic Fisheries Working Group Report. I.C.E.S. C.M./Assess: 3.Google Scholar
  10. Hilborn, R. and C.J. Walters. 1992. Quantitative Fisheries Stock Assessment: Choice, Dynamics and Uncertainty. Chapman and Hall, New York.CrossRefGoogle Scholar
  11. Hislop, J.R.G. 1984. A comparison of the reproductive tactics and strategies of cod, haddock, whiting and Norway pout in the North Sea. In Potts, G.W. and R.J. Wootton eds. Fish reproduction: strategies and tactics. Academic Press, London.Google Scholar
  12. Kirkpatrick, M., D. Lofsvold and M. Bulmer. 1990. Analysis of the inheritance, selection and evolution of growth trajectories. Genetics 124: 979–993.Google Scholar
  13. Laurec, A. and J.G. Shepherd. 1983. On the analysis of catch and effort data. Journal du Conseil International pour 1’ Exploration de la Mer 41: 81–84.Google Scholar
  14. Law, R. and D.R. Grey. 1988. Maximum sustainable yields and the self-renewal of exploited populations with age-dependent vital rates. In B. Ebenmann and L. Persson, eds. Size-structured populations. Springer-Verlag, Berlin.Google Scholar
  15. Law, R. and D.R. Grey. 1989. Life-history evolution and sustainable yields from populations with age-specific cropping. Evolutionary Ecology 3: 343–359.CrossRefGoogle Scholar
  16. Oosthuizen, E. and N. Daan. 1974. Egg fecundity and maturity of North Sea cod, Gadus morhua. Netherlands Journal of Sea Research 8: 378–397.CrossRefGoogle Scholar
  17. Pitcher, T.J. and P.J.B. Hart. 1982. Fisheries Ecology. Croom Helm, London.Google Scholar
  18. Pope, J.G. 1972. An investigation into the accuracy of virtual population analysis using cohort analysis. International Commission for the Northwest Atlantic Fisheries Research Bulletin 9: 65–74.Google Scholar
  19. Pope, J.G. and J.G. Shepherd. 1985. A comparison of the performance of various methods of tuning VPAs using effort data. Journal du Conseil International pour 1’ Exploration de la Mer 42: 129–151.Google Scholar
  20. Rijnsdorp, D., N. Daan, F.A. van Beek and H.J.L. Heessen. 1991. Reproductive variability in North Sea plaice, sole and cod. Journal du Conseil International pour 1’ Exploration de la Mer 47: 352–375.Google Scholar
  21. Sissenwine, M.P., M.J. Fogarty and W.J. Overholz. 1988. Some fisheries management implications of recruitment variability. In J.A. Gulland ed. Fish Population Dynamics. Wiley, Chichester.Google Scholar
  22. Sparre, P. 1991. Introduction to multispecies virtual population analysis. I.C.E.S. Marine Science Symposia 193: 12–21.Google Scholar
  23. Stokes, T.K. 1993. An overview of the North Sea multispecies modelling work in I.C.E.S. South African Journal of Marine Science (in press).Google Scholar

Copyright information

© British Crown Copyright 1993

Authors and Affiliations

  • T. K. Stokes
    • 1
  • S. P. Elythe
    • 2
  1. 1.Fisheries LaboratoryMAFFLowestoftUK
  2. 2.Department of Statistics and Modelling ScienceUniversity of StrathclydeGlasgowUK

Personalised recommendations