Population structure and demographic history of Genypterus blacodes using microsatellite loci

Three loci microsatellites were used to determine genetic variability and population structure at 15 locations within three zones where Genypterus blacodes is being fully exploited in Chilean waters. A total of 209 individuals were used: 77 from Cuadra Meulin (CM), 65 from the northern Magellan Strait (NMS), and 67 from the southern Magellan Strait (SMS). The genetic variability found, measured as observed heterozygosity, was Ho = 0.841 ± 0.016. The levels of population subdivision found were Fst = 0.0032 (p = 0.687 ± 0.004) and Rst = 0.0059 (p = 0.160 ± 0.003). Both the Fst and Rst values were near zero, with non-significant probability values, indicating that the three studied zones were not significantly different. The demographic history analyses did not exhibit significant differences between the observed and expected diversity, under a scenario of reduced effective population size. Therefore, the results obtained in the present study show that there was no population level genetic differentiation of G. blacodes between the analyzed zones in austral Chilean waters (between 41 and 57° S), confirming the presence of a single genetic stock. This result should be included in the management strategy by which harvest quotas are set, and used to improve the application of government management policies, with the aim of increasing the sustainability of this important fishery resource.