Dynamic Pool Models of Commercial Fisheries
This chapter traces the important contributions to the development of dynamic pool models. It explores the implications of these models for the optimal age of first capture. Whereas surplus yield models are conglomerate models which treat the biomass of the fish as a single mass of protoplasm, dynamic pool models consider the structure of the fish population. The development of dynamic pool models, then, leads to a new dimension in fisheries policy. Although simple models can be developed which allow a full dynamic analysis of dynamic pool models, this can only be accomplished under very restrictive assumptions. In an unexploited fishery, fish belonging to the older year classes are plentiful. However, as the fishing pressure increases and the population declines, the number surviving to old age also decline. The technical characteristics of harvesting fish make it impossible in practice to selectively harvest an entire year class in any one period.