Recruitment indices of Norwegian spring-spawning herring for the period 1965 -1984 based on the international 0-group fish surveys

Abstract

The trawl data from the International 0-group fish surveys in the Barents Sea are analyzed. The fishing powers of the participating vessels are estimated and corrected for. A relative index of year class strength is computed on a logarithmic scale applying the method described by RANDA (1982). The average yearly recruitment of Norwegian spring-spawning herring is very low in the period, and only the 1983 year class can be caracterized as a strong one. A few other year classes, 1966, 1973, 1979 and 1984 may be rated as slightly above the average if the 1983 year class is not taken into account. In the period 1975-82 an index of recruitment of herring was obtained through bioacoustic measurements in the fjords of northern Norway. In 1983 and 84 the distribution of 0-group herring changed and most of the 0-group herring was concentrated in the Barents Sea.