Formation of year‐class strength of breamAbramis 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 11 cm, at the end of the second summer. Mortality rates of fish larger than 11 cm were low (<50% year−1). As the number of fish at the end of the second summer was not correlated to the number of 0+ in the previous year, mortality rates during the second summer (ranging from 75.6 to 97.7% year−1) determine the final year‐class strength. These mortality rates were positively correlated to the year‐class strength of 2‐ to 4‐year‐old pikeperch. The abundance of this predator, therefore, is likely to be the most important factor controlling the year