ABSTRACT

The term model based means that observed data are fitted within a statistical framework that assumes a population dynamics model with associated parameters. This chapter discusses the history of model-based and empirical management procedures (MPs). The first MP adopted in 1974, though not explicitly evaluated until much later was model based and developed in the IWC, called the New Management Procedure (NMP). It included an HCR designed to set quotas according to the biomass depletion status of the stock as estimated by a Pella-Tomlinson production model. To demonstrate the kind of MP that could bridge the gap between traditional model-based and empirical procedures the chapter uses the example of catch biomass and long-line catch per unit effort (CPUE) data for Indian Ocean bigeye tuna. In the MSE process it was observed that the model-based approach could meet the same risk criteria as purely empirical MPs with the same input data and very similar HCRs, but achieved higher average catches.