The Regional Impacts of Climate Change

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Fishing, although largely artisinal or small-scale commercial, is an important activity on most small islands (Blommestein et al., 1996; Mahon, 1996). Although marine fisheries only account for approximately 1% of the global economy, many coastal and island states are far more dependent on the sector than this statistic would suggest (IPCC 1996, WG II, Section 16.1.1). For example, the annual yield of lobsters from the shelves and banks of the Caribbean islands (excluding the U.S. Virgin Islands) has a retail value in restaurants of approximately US$40 million (Vicente, 1996). Similarly, marine fish account for 16% of global animal protein consumption, but the contribution to protein intake is much greater in developing countries, where animal protein tends to be relatively expensive (Lauretti, 1992; Weber, 1993, 1994; IPCC 1996, WG II, Section 16.2.4).

The modest temperature increases projected for these regions are not anticipated to have a widespread adverse effect on small island fisheries. However, a temperature rise could have a negative effect on productivity in areas-such as shallow lagoons-where hypersalinity may occur, especially if juveniles are sensitive to salinity or temperature (Alm et al., 1993). On the other hand, warming-induced changes in current patterns might increase upwellings at sea, bringing more nutrients to the surface and providing more food for the fish (Aparicio, 1993; Bakun, 1993; Chakalall, 1993; Maul, 1993).

There is some evidence that clam and sea-turtle fisheries could be sensitive to sea temperature changes. Clams, like corals, are known to suffer from bleaching with the expulsion of symbiotic algae, as a result of excesses in temperature or radiation (Gomez and Belda, 1988; Lucas et al., 1988). Bleaching would cause "loss of productivity or devastation in stocks of growout clams on the reef-flats" (Wilkinson and Buddemeier, 1994). One possible option to minimize this possibility in locations where commercial clam mariculture is practiced (e.g., the Solomon Islands, Palau, Samoa) in deeper water, where light and temperature fluctuations would be reduced. This measure, however, will result in lower growth rates and reduced returns to the grower (Lucas et al., 1988; Wilkinson and Buddemeier, 1994). In the case of sea turtles, most species nest during the summer, when temperatures are close to the organisms' upper thermal limit. It is uncertain whether turtles will be able to adapt to warmer temperatures by nesting in the cooler months (Limpus, 1993). If such adaptation is not possible, increased temperatures are likely to result in a higher ratio of females to males because the sex ratio of sea turtles is directly determined by temperature (Wilkinson and Buddemeier, 1994).

Generally, fisheries in the small island states are not expected to be adversely affected by sea-level rise per se. A higher sea level would be a critical factor for fisheries only if the rate of rise were far more rapid than current projections suggest. In such circumstances, the natural succession of coastal ecosystems on which some species depend (e.g., mangroves, seagrasses, corals) would be disrupted (IPCC 1996, WG II, Section In tropical islands, these ecosystems function as nurseries and forage sites for a variety of commercially important species. Fish production obviously would suffer if these habitats were endangered or lost (Costa et al., 1994).

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