A simulation model of the sport-fishery for galjoenCoracinus capensis: an evaluation of minimum size limit and closed season
- 1 June 1990
- journal article
- Published by National Inquiry Services Center (NISC) in South African Journal of Marine Science
- Vol. 9 (1) , 359-369
- https://doi.org/10.2989/025776190784378709
Abstract
An age-structured stochastic simulation model is used to evaluate minimum size limit and closed season restrictions in terms of yield, effort and stock size for the sport-fishery for galjoen Coracinus capensis for a projected 15-year period, on the assumption that effort is increasing at 6 per cent annually. It is argued that the female stock of the Western Cape is currently recruitment-overfished with F≫F MSY , although the possibility that the stock is not recruitment-overfished is also considered. Simulated catch-at-age data for a variety of values of F show an insensitivity to the degree of stock depletion, a phenomenon ascribed to a strong size-selectivity effect. Closed-season and minimum-size options were evaluated against three possible effort-catch-rate (E-cpue) relationships, ranging from effort being independent of catch rate (cpue) to effort being entirely dependent on it. The present closed season of four months is ineffective at improving catches and counterproductive in that it reduces effo...Keywords
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