Aquaculture and fisheries

The interrelations between aquaculture and fisheries are discussed in a simple two-species system of feed fish and edible fish which can either be caught wild or farmed. Equilibria under three regimes are considered, open access, maximization of returns from each species in isolation, and global maximization. It is shown that the overfishing problem arising under open access would not be significantly ameliorated by aquaculture; the latter leads ultimately to overexploitation of feed fish. Maximizing rents from feed fish and edible fish in isolation would lead to suboptimal results, an untimely expansion of aquaculture and less total supply than possible at high enough prices. The dynamic effects of falling production costs and rising prices of edible fish are analyzed for the case of open access in capture fisheries.