Evaluation of a conservation strategy:: a spawning aggregation closure for red hind, Epinephelus guttatus, in the US Virgin Islands

Many tropical reef fishes spawn in large aggregations, which are readily targeted by fishers. By the 1980s, at least two grouper spawning aggregations were eliminated by intensive fishing off the island of St. Thomas, U.S. Virgin Islands, and another aggregating species, rad hind, was intensively targeted. By 1988, the average length of red hind had greatly decreased to 295 mm, and the sex ratio was extremely skewed to 15 females per male, suggesting a heavily fished stock. Since this species :is a protogynous hermaphrodite, the loss of large individuals (primarily males) could potentially result in sperm limitation in spawning aggregations. In 1990, a spawning aggregation closure was implemented. By 1997, average size of red hind had increased to 395 mm and sex ratio had shifted to 4 females per male. Fish were observed aggregating only in structurally complex habitat along the insular shelf edge. This habitat type is apparently not common along most of the shelf edge off St. Thomas and may provide shelter while reducing risk of predation during aggregation periods. These data suggest that protection of spawning aggregations is a sound management strategy with considerable potential for aiding the sustainable use of reef fish resources.