Protection of fish spawning habitat for the conservation of warm-temperate reef-fish fisheries of shelf-edge reefs of Florida

Abstract

We mapped and briefly describe the surficial geology of selected examples of shelfedge reefs (50–120 m deep) of the southeastern United States, which are apparently derived from ancient Pleistocene shorelines and are intermittently distributed throughout the region. These reefs are ecologically significant because they support a diverse array of fish and invertebrate species, and they are the only aggregation spawning sites of gag (Mycteroperca microlepis), scamp (M. phenax), and other economically important reef fish. Our studies on the east Florida shelf in the Experimental Oculina Research Reserve show that extensive damage to the habitat-structuring coral Oculina varicosa has occurred in the past, apparently from trawling and dredging activities of the 1970s and later. On damaged or destroyed Oculina habitat, reef-fish abundance and diversity are low, whereas on intact habitat, reef-fish diversity is relatively high compared to historical diversity on the same site. The abundance and biomass of the economically important reef fish was much higher in the past than it is now, and spawning aggregations of gag and scamp have been lost or greatly reduced in size. On the west Florida shelf, fishers have concentrated on shelf-edge habitats for over 100 yrs, but fishing intensity increased dramatically in the 1980s. Those reefs are characterized by low abundance of economically important species. The degree and extent of habitat damage there is unknown. We recommend marine fishery reserves to protect habitat and for use in experimentally examining the potential production of unfished communities. Ecosystem-oriented and single-species-oriented fishery management are based on very different goals and considerations. Ecosystem management embraces preservation of biodiversity, maintenance of ecosystem structure and function, and broad-scale climatic considerations, whereas single-species management, in practice, is concerned with optimum exploitation of desirable species. Traditional management plans, in this case, involve social, economic, and biological aspects of fisheries but rarely consider the interspecific or physical processes that impinge upon them. A marked departure from this attitude was reflected in the passage of the Magnuson-Stevens Fishery Management and Conservation Act of 1996, which in effect linked the goals of sustainable fishery production and ecosystem preservation by making habitat a central issue in the management of fisheries. Because the act requires the protection and/or restoration of essential fish habitat, it links preservation of habitat with sustainable production of fishery resources and basically encourages the ecosystem approach to fishery management. Habitat is fundamentally important to fishery production because its loss can profoundly affect productivity (Dayton et al., 1995). Benthic trawling and dredging may be especially damaging (Jones, 1992; Kaiser, 1998; Pilskalin et al., 1998; Watling and Norse, 1998), but other practices, such as removal of apex predators (Goeden, 1982) and other ecologically important species (McClanahan et al., 1999), may have equally severe reper