Fish Population Dynamic and Stock Assessment

6.1.5. Uses of the surplus production model

The advantage of surplus production model is that it can also be used to estimate a first approximation of the sustainable yield from fisheries operating on multiple stocks in a well defined area, treating them all as a unit stock. Careful examination of time series data on catch and effort would help in identifying the successive phases in the growth of a fishery from its origin to peak and then down to decline. These phases could be indicated in the relative and absolute yield curves by appropriate identification marks for each phase so as to make the model more meaningful and readily usuable as a tool for management and development decisions. This model will also serve as an excellent tool for ready estimation and judicious allocation of optimum yield and effort to solve intersectoral and interstate conflicts which are very common in the Indian fishery industry.

Relative to the Schaefer model of surplus production, the Fox model seems to be more realistic when a fishery undergoes transition from traditional to mechanized state or when mechanized fleet is added on to the existing traditional fleet, when there are changes in yield and effort in quantitative and qualitative terms.