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The genetic structure of Atlantic herring Clupea harengus was investigated in its north-easterly distribution at the Norwegian Sea and adjacent waters, using 23 neutral and one non-neutral (Cpa111) microsatellite loci. Fish from the two main suspected populations, the Norwegian spring-spawning herring (NSSH) and the Icelandic summer-spawning herring (ISSH), were collected at spawning locations/seasons from 2009 to 2012. Samples were also collected from Norwegian autumn spawning locations and from different local Norwegian fjords such as inner part of Trondheimsfjorden, Lindås pollene, Landvikvannet and Lusterfjorden, as well as from suspected Faroese spawning components. The observed level of genetic differentiation was significant but low (F ST = 0.007) and mostly attributable to the differentiation of the local Norwegian fjord populations. The locus Cpa111, which was detected to putatively be under positive selection, exhibited the highest F ST value, (F ST = 0.044). The observed genetic patterns were robust to exclusion of this locus. Landvikvannet herring was also genetically distinguishable from the three other fjord populations. In addition, the present study does not support genetic structuring among the Icelandic summerspawning herring and the Norwegian spring-spawning herring.

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Chemometric analysis of fatty acid profile in the heart tissue of redfish (Sebastes mentella, Travin 1951) from 11 locations in the waters off Norway, Faroe Islands, Iceland, and from two strata at different depths in the Irminger Sea revealed the presence of four separate stocks in the North Atlantic Ocean. The investigation has, statistically, shown: (i) a clear distinction between S. mentella on the Faroe Plateau and S. mentella in the deeps south-west of the Faroe Bank and on the Wyville Thomson Ridge; (ii) a relationship between S. mentella inhabiting the Faroe Plateau and the Norwegian Sea; and (iii) two significantly distinct stocks of S. mentella dwelling on the Icelandic Plateau. The chemometric method, consisting of methanolysis, gas chromatography of the resulting fatty acid methyl esters, and multivariate statistical treatment of the analytical data, has a discriminating power high enough to differentiate at stock level and individual level.