Recruitment indeces of the Arcto-Norwegian cod for the period 1965-1979 based on the international 0-group fish surveys

Abstract

The trawl data from the International 0-group fish surveys in the Barents Sea are analysed. The fishing powers of the participating vessels are estimated and corrected for. Relative indices of yearclass strength are computed on a linear and a logarithmic scale. The strongest yearclasses are found to be, in order, 1970, 1975 and 1973. Medium year classes are 1971, 1977, 1972 and 1974, the rest, for the period 1965-1979, is poor. These indices, when excluding the 1969 yearclass, give a correlation of 0.93 for the linear index and 0.96 for the logarithmic index for the period 1965-1975, with VPA estimates of 3-years old cod. Linear regression are used to predict the absolute size of the recruitment 1976-1979 yearclasses, and indicates an average recruitment of about 300 mill. 3-years old fish .