Analysis of Meristic Characters and Genetic Differentiation in Greenland Halibut (Reinhardtius hippoglossoides) in the Northwest Atlantic

Abstract

A stock identification study of Greenland halibut (Reinhardtius hippoglossoides) in the Northwest Atlantic was carried out based on samples from off eastern Newfoundland, Davis Strait, three West Greenland fjords and Denmark Strait. Meristic characters and frequencies of electrophoretically detectable alleles of protein loci were analyzed. Mean number of vertebrae showed significant heterogeneity among areas, while fin-ray numbers showed no difference. Offshore areas were very alike in terms of mean numbers of vertebrae, while those from the inshore areas of West Greenland differed both among themselves and from those of the offshore areas. The genetic variation between samples was small. In all samples the phenotypic distribution of four polymorphic loci was in accordance with the expectation from the Hardy-Weinberg proportions. Pair comparisons of the allelic distributions between samples showed that more than one breeding stock must exist. Although the Denmark Strait stock could not be separated from the stock in the area between West Greenland and Canada, results support the conclusion that at least two spawning stocks exist in the Northwest Atlantic. Results are consistent with the prevailing theory that Greenland halibut form a single, interbreeding stock in the offshore area between Canada and West Greenland, but also agree with other evidence that Greenland halibut in West Greenland fjords are partially isolated from the offshore stock.