A Review of the Population Structure and Ecology of Redfish in the Irminger Sea and Adjacent Waters

Abstract

Three types of Sebastes mentella in the Irminger Sea and adjacent waters have been described and there is a strong controversy about whether these types are more than one stock. Preliminary genetic studies have shown the existence of three different groups, characterised by genetic differences. The biological or ecological significance of these between-group differences, however, has not been evaluated yet. In the present paper, we review the S. mentella life cycle in the area from published data. Spawning of S. mentella in the Irminger Sea takes place in a single area above Reykjanes Ridge. The larvae drift towards East Greenland and from there they are carried to West Greenland (NAFO Subareas 0+1). Afterwards, they return to East Greenland where the main nursery area has been identified. There is an evident migration of juvenile fish from the nursery area into the open Irminger Sea, where many different cohorts are involved in the spawning fraction of the population. We also compare these data of the ecology of the species with the genetic results and we conclude that the observed genetic differences can be derived from possible genetic drift, selection or mostly from temporal variation (age dependency) which has been reported in other species with as high longevity as S. mentella. We conclude that S. mentella in the Irminger Sea and adjacent waters comprises one single stock