For this study, Antarctic toothfish samples were collected from CCAMLR Subareas 48.2, 48.4, 48.6, 88.1, 88.2 and 88.3, Divisions 58.4.1, 58.4.2 and 58.5.2, and the SPRFMO area north of Subarea 88.1. Using approximately equal sample numbers spatially across CCAMLR Areas, DNA from 761 toothfish samples were extracted and of these 547 were deemed to contain sufficient quantity and quality to be sequenced by Diversity Arrays to identify variable nucleotide SNPs sites.
The analysis of SNPs indicated that the genetic structuring of Antarctic toothfish across the Southern Ocean is very weak. The sampled toothfish shared over 99.9% of the observed variation between sites. While some genetic differences could be attributed to the longitude the samples were collected from, these differences were not sufficient to assign samples back to their location.
The combination of large-scale egg and larvae dispersal and long-distance fish movement, even at only low levels, would be sufficient to contribute to the dissolution of the genetic stock structure and explain the results found in this study. However, the actual level of genetic stock exchange is difficult to determine.