Investigations on demersal fish in the Svalbard area autumn 2003, with special attention on juvenile Greenland halibut

Abstract

Institute of Marine Research in Bergen started in 1996 a program to investigate to what degree Greenland halibut’s nursery grounds extended to the north and east of Spitsbergen, and Norwegian vessels executed this survey until 1999 with coverage with some stations into the Russian EEZ in 1998 and 1999. The annual meeting between Russian and Norwegian scientists decided to extend this survey to a joint survey, and the first year with joint effort with a Russian and a Norwegian vessel was year 2000. The survey was conducted as a traditional bottom trawl survey with main focus on Greenland halibut, but also analyses were carried out for cod, redfish and long rough dab. The main results in 2003 were: - Ice conditions in 2003 were the worst in the survey history and this caused significant limitation of surveyed area. - Water temperature on the investigated area at surface was less than in 2002, and near bottom slightly lower in the eastern part and higher in the northern area. - Due to heavy ice conditions it had been impossible to conduct observations in the important areas where dense concentrations of young Greenland halibut had been found in previous years. - It leads to a decline in the abundance indices of all Greenland halibut length groups in comparison with estimates obtained in 2002. - Abundance index for cod in 2003 was four times less than in 2002 and interpreted as the second smallest in the time series, only the result from 1998 was lower. The reduction was observed in all length groups with the exception of the young fish within 10-14 cm. - The abundance of redfishes (both S. marinus and S. mentella) was about two times higher than in 2002 in spite of the reduced distribution area. - Long rough dab abundance indices in 2003 were higher than what was found in 2002, but still remained at the low level in comparison with 1999-2001.