| dc.description.abstract | A combined acoustic and bottom trawl survey to obtain indices of abundance and estimates of length and weight at age has been carried out each winter (4-6 weeks in January- March) since 1981 in the Barents Sea. The target species are cod and haddock, but in recent years abundance indices have also been worked out for the redfish species and Greenland halibut. Since 1993 the survey area has been extended to the north and east in order to obtain a more complete coverage of the younger age groups of cod. In winter 1997 only the Norwegian part of the Barents Sea and a small part of the Svalbard area was covered, while in 1998 also a small part of the Russian EEZ was covered. In 1999 and 2000 the Norwegian vessels had full access to the Russian EEZ, In 2001 and 2002 a Russian research vessel covered most of the areas where the Norwegian vessels did not have access, and a sufficient coverage was obtained. The main results in 2002 were: - the 2001 year class of cod is very weak and the 2000 year class is indicated to be somewhat below average. The 1999 and 1998 year classes is slightly higher than expected from last years survey; - the abundance indices of 5-8 year old cod (1997-1994 year classes) are as expected from the last years survey; - the numbers of 9 year and older cod are very low; - lengths and weights at age and weight increments are similar to those observed in 2001, while some increase was observed from 2000 to 2001; - the mortality rate has been reduced compared with the previous years for age group 6 and younger, while it has remained high for older age groups; - for haddock all the year classes 1998, 1999, 2000 and 2001 are indicated to be at or above average. The 1996 year class is below average, but considerably larger than the year classes 1992-1995, which are very weak; - length and weight at age and weight increment seem to have stabilized, after a period of increase over the years 1998-2000; - the abundance indices of the redfish species are among the lowest in the time series and there are no signs of unproved recruitment; - compared to the 2001-results the abundance indices of Greenland halibut in the size range 15 to 44 cm have decreased, while they have increased for the other size groups. | en |
