(FAO 1992). Fisheries provided direct and indirect employment for about 200 million people (Garcia and Newton 1997). In addition, recreational fisheries account for large direct and indirect expenditures, especially in North America, Sweden, Australasia, and elsewhere.

The industrialization occurring in many parts of the world increases the need for foreign currency, and one way to get that currency is to sell seafood. Net fisheries exports in developing countries were worth $U.S. 16 billion in 1994 (FAO 1997a), more than the exports of coffee, bananas, rice, and many other commodities (FAO 1997b). As various fished populations decline, prices can rise. All these factors can increase fishing pressure. Recreational fishing also accounts for large landings, especially for a few game species in North America. In addition, the growing human population, increasingly industrialized, affects the terrestrial and marine environments in many ways, some of which might increase the fisheries catches, but many do not. As described in Chapter 3, destruction of spawning and nursery habitats, disruption of food webs, nutrient and other chemical pollution, and sedimentation can all adversely affect fisheries. Thus, the possibility of increasing global marine fishery catches by increasing fishing effort seems increasingly remote. Indeed, it appears likely that we will need to reduce effort to sustain the current catch rate.

Society's way of looking at marine environments also has changed. International agreements reached over the past two decades increasingly recognize the importance of marine ecosystems, the need to sustain them, and the vital links between terrestrial and marine systems. People are increasingly aware of the effects of fishing on other ecosystem components such as dolphins, turtles, birds, many invertebrates, and others. The value of the goods and services provided by ecosystems is increasingly being recognized. For example, Costanza et al. (1997) estimated the world's ecosystem services at $U.S. 16 trillion to 54 trillion per year, with more than half that value derived from marine ecosystems.

Marine ecosystem services operate over a wide range of spatial and temporal scales. They range from climate regulation, operating at the global scale, to more local services such as the provision of habitat for nursery or spawning grounds or the protection of shorelines from battering by waves. Kelp forests, mangroves, coastal wetlands, and coral reefs provide habitats and protect shorelines from erosion. Estuaries and mangroves trap sediment, thus protecting downstream ecosystems such as coral reefs. Microbes in sediments can detoxify many pollutants, and others are sequestered by the sediments. In addition to food, goods include chemicals like algin and carrageenan from seaweeds. Other services, such as biogeochemical cycling in the oceans, are obviously important, although we know little of their details. Ecosystem values include many nonmarket ones, such as opportunities for recreation and aesthetic enjoyment, as well as the ecosystem services described above (Daily 1997). Some even accrue from merely knowing that the ecosystems and their components exist, even though most people will never see them. There is increasing recognition that sustaining fishery yields



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