Allozyme and microsatellite DNA markers of toothfish population structure in the Southern Ocean

Abstract

Toothfish represent a major finfish resource in the Southern Ocean, where there has been a rapid increase in exploitation of the Patagonian toothfish Dissostichus eleginoides. Molecular genetic methods have been applied to address questions relating to stock discrimination in D. eleginoides. Eight microsatellite loci were tested in population samples from the Atlantic, Indian, and Pacific Ocean sectors of the Southern Ocean. Some loci were characterised by a large number of alleles, but no alleles were restricted to specific ocean basins. However there was a significant allelic heterogeneity in the total data indicative of population differentiation, and a high level of genetic sub‐division was measured with FST and RST. Seven polymorphic allozyme loci revealed no significant heterogeneity among Pacific and Indian Ocean sector samples. The microsatellite DNA heterogeneity suggests that there is restricted gene flow through the Southern Ocean, and that the different fishing grounds may support independent stocks.