Issue_1_09

Over the recent decades, Greenland Institute of Natural Resources (GINR) has studied Greenland halibut (Reinhardtius hippoglossoides) in Greenland waters. The studies have produced much needed information on the Greenland halibut stock structure for fisheries use. Today the emphasis in research is focused on improving biological knowledge as basis for a sustainable fisheries management.

Greenland halibut stock structure and migratory behavior has been poorly determined in the past which has resulted in inadequate stock and fisheries management. Since the mid 1980s conventional tagging with T-bar tags has improved the overall perception of large scale migration. Tagging projects and other methods in genetics and meristics have given us a better picture of the Greenland halibut stock structure.

Since 2001 The GINR has used Star-Oddi DSTs (with temperature and depth sensors) in tagging projects on the Greenland halibut. Tagging has been done in some fjords in western Greenland, where commercial fishing is high ensuring a recapture rate of approximately 10%. Acquired depth measurements have been compared to the depth contours in the area increasing the knowledge on the seasonal migration of Greenland halibut.

In September 2008 the GINR tagged 43 Greenland halibut with DST comp-tilt loggers (sensors for tilt in three dimensions, relative compass heading, temperature and depth) and 50 halibut with DST centi tags (temperature and depth). Scientists hope to recover new information on the halibut's spawning behavior - which still remains a mystery - with the new compass and tilt tags. The tagged Greenland halibuts were released in Denmark Strait (deep sea area between Iceland and Greenland), where the halibut is expected to migrate long distances as part of feeding and spawning migrations. Relative compass readings will hopefully shine light on the migratory routes over longer period of time. Further more information on important retention areas where fish spend more time spawning and feeding could be recovered.

So far only a few tags have been recovered from this study (the area where tagged halibuts were released is vast and thus expected recapture rate low). Denmark Strait is one of the most important international fishing areas for Greenland halibut in the Northwest Atlantic, and the GINR will continue the research in this area in order to further improve the fisheries management.

*DTU Aqua has a close cooperation with the Greenland Institute of Natural Resources