Abstract

Gray’s Reef National Marine Sanctuary (GRNMS) is a large (5,822 ha) expanse of live-bottom reef habitat located in 18 22 m of water, 32 km off the coast of Sapelo Island, Georgia. Designated in January 1981 as a “Sanctuary” that prohibited commercial trawling and fish trapping, GRNMS continues to be one of the most popular near-shore live-bottom reefs for sportfishing on the southeastern U.S. Atlantic coast. In 1993, we initiated a three-year sampling program to use trapping gear to determine species composition and length frequency, to compare catch-per-unit-effort (CPUE) at GRNMS with results from similar habitats and to tag fishes to estimate population abundance and detect movements. Fewer fishes and smaller black sea bass (Centropristis striata) were taken at GRNMS than at other similar, but slightly deeper (26 m) reefs. From 1993 - 1995, as CPUE of black sea bass increased at GRNMS, there was a decrease in the mean length. The CPUE of black sea bass > 20 cm increased from 1993 1994, perhaps reflecting the effect of a regional minimum size (20.3 cm TL) imposed in 1993. In 1995, however, CPUE of fish > 20 cm decreased, indicating that there may have been a loss of the larger sea bass at GRNMS despite good recruitment of juveniles, and that minimum size regulations imposed on heavily fished reefs has the same temporary and negligible effect on Gray’s Reef as it does on other overfished reefs of the region. The increase in abundance of black sea bass at GRNMS determined by the Petersen mark-recapture method from 1993.1995 showed trends similar to trap CPLJE. Tagging results indicated that black sea bass are highly resident in the Sanctuary, as 94% of the tag returns of fish at large for more than one month were recaptured in the same area that they were tagged. Fishery-independent survey data collected by MARMAP indicate declines in abundance of many exploited species and a change in community structure on reefs of the southeastern continental shelf. Data collected from heavily fished reefs in Belize show similar changes in community structure caused by fishing, when compared to completely protected marine reserves nearby. Marine reserves in Belize work to restore populations of exploited species, a size structure including large predatory fish, and a balanced fish community. GRNMS is not functioning as a reserve because of high annual harvests by recreational anglers. We suggest that some reefs, such as Gray’s Reef, must be completely closed to fishing to be true “sanctuaries” and then to be evaluated as marine reserves for non-consumptive recreation, surplus stock production, conservation of biodiversity and fishery management.

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