Abundance indices for the Arcto-Norwegian cod for the period 1979 -1986 based on investigations in June/July

Abstract

Postlarvae Surveys have been carried out in the western part of the Barents Sea in June/July since 1977. The aim of the investigations has been to study the distribution pattern of fish larvae and their relation to the distribution of water masses; and to establish abundance indices. It has been shown that mesoscale features of the larval distribution are very pronounced, and that they are connected to the circulation features. The survey strategies were changed in 1983, and emphasis was laid on the investigation of cod larvae. For all years, except for 1986, postlarval cod have been especially abundant at the bank Tromsøflaket. It is partly due to the reduced diffusion by the existence of the anti-cyclonic vortex above the bank. After three strong year classes in 1983, 1984 and 1985, the results for 1986 indicate a very poor year class, and practically no larvae were found at Tromsøflaket. The anomalous distribution in 1986 is discussed. Postlarvae and 0-group indices arc discussed and compared, and a correlation coefficient of 0.82 was found for the period 1979 -85.