Formation of year-class strength in the bream population in the shallow eutrophic Lake Tjeukemeer

Formation of year-class strength of bream Abramis brama, the most abundant fish in shallow eutrophic Lake Tjeukemeer, was studied during a 14-year period. Although the size of the spawning stock of bream was rather stable during this period, analysis of length-frequency distributions indicates that it comprised only a few year-classes. The strength of a year-class was determined at a fork length of about ii cm, at the end of the second summer. Mortality rates of fish larger than 11 cm were low