Bionomic modelling of hyperstable fish populations. The gulf corvina, Cynoscion othonopterus, fishery as case study

Abstract

Catch and fishing effort data are generally available, hence surplus production models are commonly used to conduct assessments. However, hyperstability resulting from spawning aggregations (SA) pose challenges to determine status and inform management of many fisheries resources. Using data from 1991 to 2019, we develop a method to study hyperstable fished stocks relaxing the assumption of constant catchability, hence direct dependence of catch-per-unit-effort and biomass. Information criterion was used to choose the best model including a Cobb-Douglas function for gulf corvina (Cynoscion othonopterus), a sciaenid fish endemic to the gulf of California managed through annual quotas. Bionomic stock-reduction models were fit using catch, effort, published natural mortality, virgin biomass, and economic structure. Models were solved using maximum likelihood and the best model chosen with Akaike information criterion. Current fishing effort is beyond bionomic optimum. This deserves a precautionary approach to protect this endemic species and sustain the fishery.