the local extinction of a species, for example the common skate (Raja batis) in the Irish Sea (Brander 1981); the barndoor skate (Raja laevis) may be near extinction throughout its range in the Northwest Atlantic (Casey and Myers 1998). But the precise nature and timing of the interactions related to multispecies fisheries are very hard to predict (Pikitch 1988).
Finally, many fishery-management agencies have mandates and goals that are potentially in conflict. They are often asked to promote fishing and the fishing industry and to protect the ecosystem and the individual species in it. Sometimes, a goal—often unspoken but occasionally explicit (e.g., Task Force on Atlantic Fisheries 1983)—is the preservation of a fishing community's way of life. How fishery management affects fishing communities is a major issue all over the world. In the United States, the Sustainable Fisheries Act of 1996 requires fishery impact statements that assess the likely effects of management measures on fishing communities. The difficulty of dealing with goals that are not made explicit—much less agreed on by most of the parties involved—is common to many resource agencies, not only fishery agencies. While it can dealt with, it often does not receive the attention it deserves.
Enforcement is often a difficult problem for fishery managers and is related to many of the scientific uncertainties described above (involving biological and social sciences). The incentives to bend the regulations or to cheat are many, and there are so many participants in most fisheries that it is impossible to prevent or catch all violations. Sometimes the regulations themselves are confusing or not well disseminated, resulting in unintentional violations. Recreational fisheries are particularly difficult to monitor, and to some degree they depend for compliance with regulations on an honor system. The problem is well known, and because it involves illegal activities, solutions are made more difficult. We provide one example, that of whaling.
International whaling is controlled by two organizations, the International Whaling Commission (IWC), which allocates catch limits, and the Convention on the International Trade of Endangered Species, which regulates the import and export of endangered species. Both organizations tightly restrict the hunting and trade of all baleen whales plus sperm whales. The IWC adopted a moratorium on commercial whaling in 1986 (Marine Mammal Commission 1998), although some species like the humpback whale and the blue whale have been fully protected since the mid-1960s. About 500 to 600 whales are taken each year for research or aboriginal use, the bulk of which are minke whales taken under scientific permit to Japan. The purpose of the IWC is to sustainably manage the whaling industry and as such it represents an important example of international fisheries control for the benefit of sustainable exploitation of global natural resources.