The economic value of environmental data: A notional insurance scheme for the European anchovy

Abstract

To explain atypical events in anchovy population dynamics in the Gulf of Cadiz, it is crucial to consider environmental processes in a different way from how these are traditionally included in stock-recruitment relationships. In the Gulf of Cádiz, sea surface temperature, intense easterlies and discharges from the Guadalquivir river have been identified as key factors determining anchovy's early life stage mortality. We have constructed an environment-based recruitment model that estimates abundance of juveniles, as well as crucial parameters for the fishery such as natural and fishing mortality. There are few estimates for these parameters in the Gulf of Cádiz because of the lack of reliable information in contrast to other anchovy fisheries. Bayesian state-space models enable estimation of parameters with fewer data than non-Bayesian approaches because they allow the incorporation of prior knowledge. We are able to evaluate how modelling environment-based recruitment affects stock assessment and how responding to environmental information can benefit fisheries management. Further, by simulating a notional insurance scheme we are able to measure the value of using environmental information within a specific management regime defined by a harvest control rule. The main questions are whether incorporating the knowledge of environment in the management of anchovies in the Gulf of Cádiz is likely to reduce the volatility of the population dynamics of Anchovy and how this could benefit the commercial fishery andecosystem management.