Individual Vessel Quotas and Increased Fishing Pressure on Unregulated Species

When individual vessel quotas are used in fisheries management, quotas are in most cases set species by species. In general, it is only the most important of the target species that are regulated by quota. There is a growing concern that the introduction of individual vessel quotas by removing fishing capacity from quota species leads to increased fishing pressure on unregulated species. To model fishermen behavior with this regulatory structure a constrained profit function where the quota species are treated as fixed while the unregulated species are variable is used. An empirical analysis is provided for Norwegian purse seiners, and the empirical results indicate that for the most valuable species there is a one to one relationship between changes in quota and changes in the harvest of unregulated species.