Conservation genetics of the bonnethead shark Sphyrna tiburo in Bocas del Toro, Panama: Preliminary evidence of a unique stock.

Abstract

The bonnethead shark, Sphyrna tiburo, is a small elasmobranch distributed in the Eastern Pacific from southern California to Ecuador, and along the Western Atlantic, with preferences for continental margins of North, Central and South America, the Gulf of Mexico, and the Caribbean. Recent studies have suggested that it could be under a process of cryptic speciation, with the possibility to find different species in similar geographic locations. Here we assessed the population structure and genetic diversity of this highly philopatric and non-dispersive species in the Bocas del Toro Archipelago, Panama. Fragments of the mitochondrial genes cytochrome oxidase I and control region, were used to test the genetic structure of adult and juvenile S. tiburo in this area, and were compared with other locations of the Western Atlantic and Belize. We found significant genetic differentiation between Caribbean bonnethead sharks from Bocas del Toro and Belize, when compared to bonnetheads from other locations of the Western Atlantic. These results also suggest that Bocas del Toro could constitute a different genetic population unit for this species, whereby bonnethead sharks in this area could belong to a unique stock. The information obtained in this study could improve our understanding of the population dynamics of the bonnethead shark throughout its distribution range, and may be used as a baseline for future conservation initiatives for coastal sharks in Central America, a poorly studied an often overlooked region for shark conservation and research.