Population genetic structure of barramundi (Lates calcarifer) across the natural distribution range in Australia informs fishery management and aquaculture practices

Clarifying population structure of fish stocks is important for the sustainable exploitation of fisheries, along with informing collection of founder broodstock for the genetic improvement of aquaculture programs. Using 16 microsatellite DNA markers, the most comprehensive genetic survey to date (1297 individuals from 49 sample collections) of the population structure and genetic diversity of wild Australian barramundi (Lates calcarifer) was undertaken. The results point to the existence of two distinct genetic stocks (east and west) with isolation by geographic distance (IBD), and a central region of admixture between the stocks, located in an area where a historic land bridge once connected northern Australia with Papua New Guinea. Global levels of population differentiation were moderate (fixation index, F_ST = 0.103, P < 0.001) and IBD was identified as a factor influencing population structure across the sampled region. There was also evidence of temporal stability of population genetic structure over a period of 25 years. This study provides valuable information for improving programs of translocation, restocking and captive breeding for both the wild barramundi fishery and the aquaculture industry.