Abstract

The Nassau grouper, Epinephelus striatus, is a large serranid which is widely distributed throughout the western tropical Atlantic. This protogynous species forms large spawning aggregations at spatially and temporally predictable locations along the edge of insular and continental shelves. Larvae may remain in the plankton for over a month, but the extent to which they are dispersed during this period is unknown, and little is known about possible population subdivision within the range of this species. The purpose of this study was to identify any stock separation which may exist among localized populations of Nassau grouper within the western tropical Atlantic from four spawning aggregation in Belize, Central America as well as from Florida, Cuba, and the Bahamas. Microsatellite markers were developed using a DNA cloning procedure. Sample sites were then compared based on genotypes obtained by PCR amplification and electrophoresis of two microsatellite regions of Nassau grouper DNA. Tests for deviations from Hardy-Weinberg equilibrium and heterogeneity among allele and genotype frequency distributions revealed no conclusive evidence for stock separation among sample sites. These result simply that spawning aggregations are not exclusively self-recruiting, and that larvae are at least occasionally dispersed over great distances.

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