Population structure and connectivity of tiger sharks (Galeocerdo cuvier) across the Indo-Pacific Ocean basin

Abstract

Population genetic structure using nine polymorphic nuclearmicrosatellite loci was assessed for the tiger shark (Galeocerdocuvier) at seven locations across the Indo-Pacific, and onelocation in the southern Atlantic. Genetic analyses revealedconsiderable genetic structuring (FST > 0.14, p < 0.001) betweenall Indo-Pacific locations and Brazil. By contrast, no significantgenetic differences were observed between locations fromwithin the Pacific or Indian Oceans, identifying an apparentlarge, single Indo-Pacific population. A lack of differentiationbetween tiger sharks sampled in Hawaii and other Indo-Pacificlocations identified herein is in contrast to an earlier globaltiger shark nDNA study. The results of our power analysisprovide evidence to suggest that the larger sample sizesused here negated any weak population subdivision observedpreviously. These results further highlight the need for cross-jurisdictional efforts to manage the sustainable exploitation oflarge migratory sharks like G. cuvier.