Growth in the Norwegian spring-spawning herring for the year-classes 1950 -1960 and 1973 -1983

Abstract

Two periods with great differences in year-class abundance and recruitment where chosen for growth studies. In the first period the mean year-class strength at 3 years was 6 790 x 10[6] individuals while in the second period the average recruitment at age 3 was 436 x 10[6]. The growth in each year-class, as observed by the length and weight at age, is compared to the year-class strengths in the two periods in question. Variations in growth is observed and before maturation, strong year-classes has remarkable less growth both in length and weight than weak year-classes. The latter period in question is therefore characterized by far better growth in these early years of life than the former. After maturation however, the difference in growth between the two periods is far less distinct.