Metapesca: a simulation model to explore management options in benthic invertebrate fisheries

J.L. VALERO; A.M. PARMA; B. ERNST; J.M. ORENSANZ

Vancouver

Congreso; Fourth World Fisheries Congress; 2004

American Fisheries Society

Sedentary marine resources challenge most assumptions of conventional fisheries assessment and management. Spatial heterogeneity in stock dynamics (growth, reproduction and recruitment dominated by density-dependent or environmental local effects) and the fishing process (local persistence of fishing effects, serial depletion) often complicate data collection and interpretation, and limit the effectiveness of catch and effort controls at the global scale. Metapesca is a general model of the dynamics of an exploited metapopulation of benthic invertebrates. The stock is divided into subunits (subpopulations) of sedentary adults inter-connected by dispersing larvae. Population dynamics are age-structured. Compensatory and depensatory effects are modeled for pre- and post-dispersal stages. The fishing process is modeled with algorithms of effort allocation. Global (total catch, effort) and spatial (rotation, temporary closures, permanent reserves) controls can be used to explore management strategies. There are two versions of the model: a user-friendly version used as a tool for setting up relevant scenarios in workshops, and an optimized version to be used as operating model for exploring alternative management procedures specific to each fishery. This approach will allow a formal evaluation of alternative harvest rules in concordance with data collection and analysis that will assist management decisions and provide a robust alternative to assessment-based approaches. Case studies of our modeling approach are Tehuelche scallop (Aequipecten tehuelchis) in Argentina, sea urchin Loxechinus albus) and loco (Concholepas concholepas) in Chile, and geoduck clams (Panopea spp.)in USA-Canada and Argentina.