Genome-wide evaluation of Scylla serrata (giant mud crab) population structure between and within two continental shelf regions of northern Australia

Context Offshore spawning and larval distribution of the wide ranging Scylla serrata (giant mud crab) provides genetic connectivity potential across large spatial scales. Aims We examined the genetic connectivity of S. serrata between and within two large continental shelves of northern and eastern Australia, to inform fisheries assessment and management. Methods Over 300 individuals were sampled from 14 locations, within 6 oceanographic regions, across the 2 continental shelves, providing 40,364 single nucleotide polymorphisms (SNPs) for analysis. Key results Results indicated a single genetic stock along the eastern continental shelf of Australia with no evidence of north to south structuring. A separate genetic stock on the northern continental shelf of Australia was indicated, with evidence supporting a degree of east–west structuring of S. serrata populations within the Gulf of Carpentaria. Conclusions The spatial extent of genetically connected S. serrata metapopulations is likely dependent on the oceanographic features of a region. The spatial scale of S. serrata stocks should be assessed on a case-by-case basis, confirmed by empirical evidence (e.g. SNP analysis) given connectivity is likely dependent on regional oceanographic conditions. Implications The outcomes of this study have implications for management of fished S. serrata stocks, especially where fishing mortality may (or may not) have effects beyond the jurisdiction of interest.