Fishery composition and evidence of population structure and hybridization in the Atlantic bonefish species complex (Albula spp.)

Abstract

The distributions, genetic structure, and occurrence of hybrids were explored among three Atlantic bonefishes (Albula spp.), to determine recreational fishery composition, using 19 microsatellite loci. Between 1977 and 2012, study specimens were obtained from 14 locations across the Caribbean Sea and western Atlantic Ocean, with an external collection from the eastern Atlantic. The species were broadly sympatric across the region, though occurrence at the local level was variable, likely due to habitat partitioning. Albula vulpes appeared to be the primary contributor to the recreational fishery, which occurs predominantly in coastal flats habitats. Unexpected, non-geographic population partitioning was identified within all three species. Robust evidence for two genetic populations of A. vulpes was further supported by hypothesis testing for migration patterns between them. The potential existence of two quasi-discrete spawning groups (fall and spring) within species may explain the observed partitions. Patterns of interspecific hybridization were explored to further inform management and conservation efforts. Hybrids were observed at low frequency (40 individuals, equaling a 1.5 % hybridization rate), and most were collected from Florida and The Bahamas. Our results suggest that a combination of intrinsic and extrinsic semipermeable barriers to gene flow exists among these divergent species. These findings are congruent with previous studies that revealed substantial genetic divergence among these secondarily sympatric bonefishes. Further, clarification is provided on regional distributions and the composition of the economically and culturally important recreational fishery. On first order, management efforts would have the greatest impact if focused on A. vulpes populations and their preferred habitat.