Undersøkelse av torsk, hyse og uer i Barentshavet vinteren 1990
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The combined acoustic and bottom trawl survey in the Barents Sea in winter has been carried out since 1981. The target species are cod and haddock, but in recent years the redfish species in the area have also been included. In 1989, rock hopper gear was introduced in the bottom trawl survey. This gives considerably higher catchers of the smallest individuals than the bobbins gear. A double set of indices are presented for the bottom trawl survey, one for bobbins gear and one for rock-hopper gear, with indices back-calculated ffrom one gear to the other in the appropriate years. For cod, the acoustic survey gave a total estimate in numbers which was 73 % higher than in 1989, and the bottom trawl survey (rock-hopper gear) a total 16 % higher than in 1989. The corresponding figures for haddock are 85 % and 169 %. The increase is in both surveys largely due to increase in the number of 1-group fish. Thus, the 1989 year class of both species appears to be stronger than the 0-group survey in August-September indicated, and may be of average abundance. Otherwise, the results seem to be in reasonably good agreement with the predictions of stock numbers at age of cod and haddock in the last assessment. For redfish, the bottom trawl indices have not been corrected for the change from bobbins to rock-hopper gear and the effect of the change is not known. The abundance indices from both surveys indicate that the stock situation for Sebastes marinus and Sebastes mentella is stable within the investigated area. The indices for Sebastes viviparus increased in 1990. Indices for the smallest length group are considered unreliable for all three species.