Fish Stock Assessment Models with Emphasis on the use of the Classic Gordon Schaefer Model: A Review

The main objective of stock assessment is to assure, in the long run, of the self-sustainability of the stock. In this paper, we discuss fish stock assessment methods. We present the advantages and disadvantages of each method discussed. Morden approaches to fish stock assessment include multispecies, multi-gear and ecosystem approaches. However, most of these approaches are expensive to apply in developing countries. Simple methods sometimes may perform as well as, or even better than complex methods. We discuss the Gordon Schaefer (GS) model as an alternative method for assessing fishery stocks in developing countries, with Malawi as an example of a developing country. We review how the GS model has been applied globally in general and in Malawi in particular. The review shows that most studies have concentrated on the calculation of maximum sustainable yield or maximum economic yield leaving out other reference points. The use of all reference points, including open access yield and optimum sustainable yield, is important in making correct management decisions. Bifurcation analysis, calculation of annual sustainable production and calculation of depletion are missing in most studies. Future research could focus on integrating the use of all four reference points, bifurcation analysis and calculation of depletion as well as annual sustainable production.