Elucidation of fine-scale genetic structure of sandfish (Holothuria scabra) populations in Papua New Guinea and northern Australia

The development of a sandfish (Holothuria scabra) mariculture industry within Papua New Guinea (PNG) is of great socio-economic importance. However, the lack of knowledge surrounding the current population genetic structure throughout the region has raised concern about the genetic impacts of hatchery-augmented sea ranching on already diminished wild populations. The present study evaluated the current population genetic structure of sandfish within PNG, and more broadly across northern Australia, to inform sustainable mariculture practices and provide baseline genetic data within these regions. Microsatellite-based population genetic analyses were used to determine the genetic diversity within subpopulations. This analysis found that although microsatellite loci varied widely in the number of alleles (3–28), the overall allelic diversity was similar among all populations sampled. The level of genetic substructuring among all populations sampled was low, although significant (FST = 0.037, P = 0.000). Most of these differences were driven by distinctness of the Australian populations from those in PNG, whereby results indicated that PNG populations exhibited a panmictic stock structure. No distinct patterns of genetic isolation by distance were detected among the populations examined. Information obtained from the present study will improve the management of restocking programs and support a sustainable future for the PNG sandfish mariculture industry