Multispecies modelling of some components of the marine community of northern and central Patagonia, Argentina

Using a bioenergetic and allometric approach, we developed multispecies trophodynamic models of the marine community of northern and central Patagonia in the southwestern South Atlantic Ocean that included hake (Merluccius hubbsi), squid (Illex argentinus), anchovy (Engraulis anchoita), and South American sea lions (Otaria flavescens). We used these to explore the effects of model structure and parameter uncertainty on predictions of the effects of different management regimes using continuation and bifurcation analysis. We considered five different functional responses and used the Akaike Information Criterion for model selection. The best models involved laissez-faire Holling Type III-shaped functional responses and the worst one corresponded to the Ecosim form. These models showed many similar behaviours but also showed marked differences in some exploitation scenarios. This suggests that using a single model structure as the basis for managing these stocks could lead to misleading, and potentially dangerous, conclusions.