A grey nurse shark from the Northern Territory of Australia shares a mitochondrial haplotype only recorded from the western Australian population

Context The critically endangered grey nurse shark (Carcharias taurus) is a widely distributed coastal to near coastal species. Overexploitation has resulted in severe global population declines, including in Australian waters, where two genetically distinct populations are known to exist in temperate to subtropical waters off the eastern and western coasts of the continent. However, occasional sightings of C. taurus have been reported in the Timor Sea and Northern Territory waters. Aims In this small-scale study, we aimed to evaluate whether a single C. taurus individual captured in waters off the Northern Territory of Australia belongs to the Critically Endangered eastern Australian population. Methods On the basis of previously identified mitochondrial haplotypes for this species, we aligned the mtDNA control regions of the Northern Territory individual with sequence data from eastern and western Australian samples. Key results The sequence alignment showed a haplotype unique to western Australia (Haplotype E). Conclusions The individual caught in Northern Territory waters is genetically compatible with the western Australian population. Implications These data suggest that C. taurus occurring off the Northern Territory do not represent an extension of the Critically Endangered eastern coast population and also highlighted the need for future research on the understudied grey nurse shark in tropical waters off northern Australia.