Abstract

The Atlantic Sharpnose Shark, Rhizoprionodon terraenovae, and the Caribbean Sharpnose Shark are small coastal-temperate and tropical sharks of the continental shelves that overlap in distribution along the Gulf of Mexico, Florida and around the Yucatan Peninsula to the Caribbean Sea. In order to properly distinguish between the two species, current methods require counting caudal and precaudal vertebrate. These species used to be higbly abundant within their prospective ranges, but current fishery pressures have caused declines in landing. Assessment of population size and structure is necessary to determine future management plans for this species. Use of SSCPs is a viable method to differentiate between the two species and to measure population structure. SSCP analysis was able to detect unique haplotypes indicative to a particular species. Use of sequencing confirmed the variation between the species with an estimated nucleotide divergence as high as 1.08 %. AMOVA analysis comparing Atlantic sharpnose sharks collected in the Bay of Campeche with samples obtained from four other sites throughout the Gulf of Mexico and along the Northwestern Atlantic Ocean found that the eleven haplotypes observed were evenly distributed throughout the range (Öst = 0.022, p = 0.191). However significant differences were observed in pairwise analysis between the Bay of Campeche and other sites. These differences disappeared when samples were examined based on temporal data suggesting that genetic bottlenecking is occurring in the R. terraenovae along the Mexican Coast.

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