A SURPLUS PRODUCTION MODEL WITH A NONLINEAR CATCH-EFFORT RELATIONSHIP

Surplus production models have been used in fisheries analysis for over 40 years. The traditional surplus production model incorporates the assumption that catch per unit of effort is constant for a given stock size. As a result, effort can be indefinitely applied to the fishery in the short term, and catch would indefinitely increase at a constant rate. In this paper, a surplus production bioeconomic model is developed using a nonlinear form of the short-run catch equation based on the Spillman production function. Two long-run models were derived using the logistic and exponential growth models. The parameters for the long-run equilibrium models are estimated from catch and effort data using a disequilibrium form of the model. The models were applied to data for the Hawaiian lobster fishery used in the analysis by Clarke, Yoshimoto, and Pooley (1992). The results were compared with the results derived from conventional forms of the surplus production model. The key parameter values were similar to those reported by Clarke, Yoshimoto, and Pooley, but the amount of variation in the data explained by the new formulation of the models was generally higher.