The Optimal Allocation of Ocean Space: Aquaculture and Wild-Harvest Fisheries

Research PaperIn many estuarine and ocean areas, aquaculture is seen as an alternative to traditional commercial fish harvesting practices. A significant problem hindering the emergence or the continuing growth of aquaculture in many areas is the conflict that arises among it and other competing ocean uses. Real world examples include the incipient conflict between rights-based commercial fisheries and the marine culture of the green-lipped mussel (Perna canaliculus) in New Zealand and the debate over shellfish leases and wild-harvest production of hard clams (Mercenaria mercenaria) in small estuaries on Cape Cod. We consider the resource manager’s problem of allocating ocean space in a circumscribed region defined by a fishery. We develop a bioeconomic framework to help clarify the choice of the optimal scale of aquaculture when that use impacts the fishery. We identify a range of potential impacts, both positive and negative, but we focus on negative impacts that affect the carrying capacity of the fish stock. Numerical simulations are developed to illustrate two cases: (1) aquaculture and fishery uses compete only over ocean space; and (2) these uses compete both over ocean space and in the downstream product market. Preliminary simulation results for a hypothetical case focusing on fluke (Paralicthys dentatus) in Rhode Island Sound suggest that social optima often may be associated with corner solutions (i.e., the ocean area should be devoted exclusively either to aquaculture or to the fishery). These results imply that, under certain conditions, the coexistence of both types of uses may not be economically optimal