Population structure of the Australian gummy shark (Mustelus antarcticus Gunther) inferred from allozymes, mitochondrial DNA and vertebrae counts

The gummy shark (Mustelus antarcticus) is the main target of southern Austr alian shark fisheries. Its stock structure was investigated through allozym es (up to 28 loci), mitochondrial DNA (up to 10 restriction enzymes) and ve rtebrae count. The average heterozygosity per allozyme locus (0.099) and de gree of polymorphism (0.255) was high for sharks. Composite mitochondrial D NA haplotype diversity (0.534) and mean nucleotide sequence diversity (0.16 %) were also moderately high. Three of the seven polymorphic allozyme loci (CK-A*, LDH-1*, PEP*) and the mtDNA haplotypes showed significant spatial d ifferentiation. Two genetic stocks were identified: one along the southern coast of Australia from Bunbury in Western Australia:to Eden in New South W ales and one off northern New South Wales (in the region of Newcastle to Cl arence River). There was some evidence for a third stock off Townsville, Qu eensland. The northern occurrences extend die known geographical range of t his species. Vertebrae counts from Eden northwards increased, supporting th e conclusion of population heterogeneity off eastern Australia.