Chilean fishing law, maximum sustainable yield and the stock-recruitment relationship

During 2013, the Chilean fishing law was amended to incorporate, among other changes, the maximum sustainable yield (MSY) as target reference point for managing fishery resources. This mandate triggered the estimation of MSY-based reference points (RPs) in each fishery subject to catch limits in Chile. Recent investigations indicate that production models provide MSY-based RPs, which are predicted only by using the steepness of the stock-recruitment relationship (h). In this paper, we compare predicted MSY-based RPs using production models with estimates from an age-structured per-recruit model for eleven demersal stocks harvested in Chile. The MSY-based RPs assessed were: 1) The ratio between the biomass leading to MSY to the unfished biomass (B-msy/B-0); 2) the ratio between the fishing mortality that gives the MSY and natural mortality (F-msy/M); 3) the ratio of spawning biomass per recruit (SR) when the population is fished at F-msy to the spawning biomass per recruit of an unfished population (SR(F-msy)/SR0 = SPRmsy). The production model provides B-msy/B-0 and SPRmsy that well predicted estimates from the age-structured models in most of the species analyzed. However, F-msy/M was overestimated by the production model in most of the stocks. We discuss the dependence of h with the MSY-based RPs in light of the Chilean fishing law. This paper reveals the complexity of implementing the Chilean Fishing Law into real situations and the uncertainty surrounding the estimation of h and, by extension, MSY and MSY-based RPs.