Review on fish stock assessments models with more emphasis on the use of empirical and analytical models for potential yield prediction

Abstract

The basic purpose of fish stock assessment is to provide estimates of the state of the stock to assure, in the long run, the self-sustainability of the stock under exploitation. The three commonly used stock assessment models are reviewed in this paper namely Surplus production model, Empirical model, and Analytical Model. The first model is simpler and considers the stock as a homogenous biomass. It ignores the complexities of age structure and spatial structure and assumes compensatory population growth and provides fishery managers with some important management parameters. Nonetheless, it requires a long time series catch and effort data and assumes stock has stabilized at a current rate of fishing and its ability to accurately describe and predict the dynamics of fish populations depends greatly on the nature of the available data. The second model makes a link between some easily measured characteristic of a water body, such as its area/depth, the conductivity of the water or the mean primary production and an expected yield. However, a major limitation of the Empirical model is that previously observed empirical relationships may break down in situations when conditions change substantially. The third model, on the other hand, requires a detailed description of the stock such as size or age structure of the stock as well as growth and mortality parameters that characterize the population under investigation. As an advantage, this model gives a reliable estimation of yield and biomass of fish that could be exploited sustainably from a given water body. However, such model has been poorly used in developing countries. Since, it is complex, slow, costly and time-consuming. In conclusion, understating the limitation, advantages and applications of each stock assessment model is very important to make a reliable estimate of vigorous fisheries management parameters in order to manage our aquatic resources sustainably.