Migration and recruitment to the commercial stock of Greenland halibut, Reinhardtius hippoglossoides (Walbaum), in the Svalbard area

Abstract

Results of stratified bottom trawl surveys in the Svalbard area during the period 1983-1985 show that depth distribution of Greenland halibut is size dependent. Higher proportions of large fish are found in deeper strata. The species exhibits geographically heterogeneous length distributions with a relatively high proportion of small fish north of 76°K. This inter-area heterogeneity could be attributed to a southwards migration of larger fish from nursery grounds in the north. Recaptures of fish tagged in the northern area supports this view in that fish not recaptured in the release area had moved southward. During the period of investigation a general decrease in the abundance of small Greenland halibut was observed in the Svalbard area. This is interpreted as indicating reduced recruitment success. 4 possible connection between the decreasing recruitment of Greenland halibut and an increase of young cod. Gadhus morhua (L.), abundance is discussed.