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Size, Composition, and Spatial Structure of the Annual Spawning Aggregation of the Red Hind, Epinephelus guttatus (Pisces: Serranidae)
Douglas Y. Shapiro, Yvonne Sadovy and M. Angela McGehee
Vol. 1993, No. 2 (May 3, 1993), pp. 399-406
Stable URL: http://www.jstor.org/stable/1447138
Page Count: 8
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Annual spawning aggregations of the red hind, Epinephelus guttatus, occurring at the time of full moon in Jan., were surveyed off the southwest coast of Puerto Rico between 1983 and 1989. One aggregation in 1984 measured 70 × 140 m and contained a fish density that increased over a period of four days to a maximum of 7.6 fish per 100 m2 on the day of the full moon and then declined over two subsequent days. The female-to-male sex ratio was 5.6 for samples of fish speared on the bottom and 7.1 for those caught from the surface on hook-and-line. This difference is not significant. Within the aggregation, fish formed clusters of two to seven individuals. Speared clusters contained either one male and two to three females or all females. In a 1986 aggregation, the dispersion pattern of all individuals within a large grid was evaluated with nearest-neighbor analysis. During the first two days of the aggregation, fish were distributed randomly. In the final three days, which included the day of full moon and the period when individuals probably spawned, fish were significantly clumped. This statistical pattern of clumping confirmed divers' impressions of fish in clusters, suggesting that spawning is not random but occurs in clusters containing one male and a few females. These results suggest that aggregations function primarily to enable males and females to find mates.