Incentives for optimal management of age-structured fish populations

We characterize optimal fishery management in an age-structured, bio-economic model where two age groups are harvested with costly and imperfect selectivity. We show that a system of tradable fishing permits, each allowing to harvest a specific number of fish that differs with age group, implements optimal age-structured harvesting, while traditional biomass quotas fail to solve the problem of growth overfishing. With our system, gear restrictions (such as mesh-size prescriptions) become obsolete. We apply our model to the Eastern Baltic cod fishery and quantify the benefits of optimal age-structured management.

► We develop an age-structured fishery model with costly selectivity of age groups.
► We propose a new regulation with tradable fishing permits based on the number of fish.
► A permit allows to harvest specific numbers of fish that differ with age group.
► With our system gear restrictions (e.g. mesh-size prescriptions) become obsolete.
► We quantify and apply the model to the Eastern Baltic cod fishery.