THE DIFFERENTIAL ALTERNATIVE TO THE DERISO DIFFERENCE PRODUCTION-MODEL

A differential approach is developed as an alternative to the Deriso (1980) difference production model. In this, the von Bertalanffy growth function may be applied and the number of parameters to be estimated within the model may be reduced by one. It is shown that the Deriso model may fail when the population exhibits the von Bertalanffy growth pattern. The concept of a fishing mortality keeping stock biomass constant in the period between recruitment processes is presented. The models are applied to simulate the Eastern Baltic cod stock. © 1992 International Council for the Exploration of the Sea.