Morphology and biochemical genetics of Atlantic halibut, Hippoglossus hippoglossus (L.), from various spawning grounds

Potential phenotypic/genotypic differentiation of Atlantic halibut, Hippoglossus hippoglossus (L.), samples from two spawning grounds in north Norway (Malangen and Sørøysund) were studied. In addition, the genetic relationship between fish from north Norway, mid–Norway (Folia) and western Greenland (off Fredrikshåb) was investigated. Uni– and multivariate analyses of 15 morphometric measurements and six meristic counts revealed a considerable degree of homogeneity between Malangen and Sørøysund. No morphological characters were thus found suitable as diagnostic tools in the classification of potential halibut stocks. As determined from electrophoretic studies, the allelic distribution at the four polymorphic loci ADA, PGI–2, PGM–2, and UTP (unidentified tissue protein) did not vary significantly when all four samples (Folia, Malangen, Sørøysund and Greenland) were considered together. However, when the Norwegian coast samples were split into a northern (Sørøysund and Malangen) and a middle (Folla) area, and each locus was regarded isolated, significant heterogeneity was detected at the PGM–2 locus, thus giving evidence for a potential heterogeneity along a north–south axis.