Discrimination of the redfish (Sebastes mentella) stock components

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The study material was collected in 2004 and 2005 during commercial cruises to the Irminger Sea on board the Polish vessel MT “Wiesbaden”. The ichthyological studies of the pelagic Sebastes mentella include detailed biological analyses, length measurements, otolith collection for age determinations, and digital images of the redfish for meristic and morphometric characters analysis. Comparison of the pelagic redfish from the northeastern and southwestern areas of the Irminger Sea indicates that there are a number of differences, including differences in spatial and vertical distribution, ambient temperature, length and age composition and morphometric–meristic characteristics. Significant differences between fish samples from the northeastern fishing grounds at depths greater than 500 m and fish from the southwestern fishing grounds at depths shallower than 500 m were observed in the number of fin rays in the back part of the dorsal fin, in the pectoral fin, and in the number of gillrakers. The share of the “pelagic deep‐sea” component in the northeastern area was nearly 92%, whereas the “oceanic” component dominated in the southwestern area and comprised more than 88% of the fish there. Cluster and principal component analyses suggest that the oceanic component is a more homogeneous group than the deep‐sea component. The results support the management units recently advised and established by ICES.