habitat and consideration of actions to conserve such habitat (section 110). Congress also required NMFS to convene a panel to consider ecosystem-based approaches to U.S. fishery management (NMFS in press).

Conservative Single-Species Management

The most obvious management approach is to reduce the catch of depleted species on a single-species basis. If Georges Bank is a prime example of the effects of overfishing in the United States, the case of striped bass on the U.S. east coast is a shining example of the effects of catch controls on a single species. Striped bass populations collapsed throughout the mid-Atlantic region and elsewhere in the late 1970s (Richkus et al. 1992). Chesapeake Bay is thought to be the nursery ground for 60 to 80 percent of striped bass off the east coast of the United States. In 1984, Congress passed the Striped Bass Conservation Act, giving states authority to place moratoria on fishing for striped bass. In 1985, Goodyear published calculations showing that control of fishing for bass would lead to a rebuilding of the populations, even if the decline had causes other than overfishing (Goodyear 1985). Led by Maryland, which imposed a moratorium on striped-bass fishing in Chesapeake Bay in 1985, and Virginia in 1988, the east-coast states increasingly controlled fishing effort. In early 1995, striped bass were declared by the Atlantic States Marine Fisheries Commission to be fully recovered (NMFS 1996a).

Other species have also responded to controls applied on a single-species basis. Indeed, Myers et al. (1995) concluded, based on an examination of life-histories, that almost all overexploited fish populations would recover if fishing were stopped. For example, both king (Scomberomorus cavalla) and Spanish (S. maculatus) mackerel catches off the southeastern and Gulf coasts of the United States have been severely restricted since the mid-1980s. Spanish mackerel were removed from overfished status to fully exploited status in 1995, and their populations have shown considerable increases (NMFS 1996a). There is some optimism that king mackerel populations will increase as well. Pacific halibut have long been managed on a single-species basis and have supported a sustainable fishery since the 1920s.

Several specific methods of implementing conservative management have been described. Marine protected areas are discussed in detail below. Another approach is to adopt a fixed exploitation rate (as opposed to a fixed catch) (NRC 1996b, Walters and Parma 1996). Another is to allow fish to spawn at least once before they are fished (Myers and Mertz 1998). Myers and Mertz pointed out that this approach was recommended more than 100 years ago (Holt 1895), but that other approaches, such as maximizing yield from somatic growth, had reduced its influence on management. They also provided practical guidance, emphasizing that susceptibility of populations to overfishing is very sensitive to the age at which they are first caught. Populations that can be caught while young



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