Task 2: Broodstock management. sub-task 2.1: Extension of the natural reproduction period - early or delayed spawning (WP2)

The overall objective of the task was to extend the spawning period of ‘wild’ common perch from some weeks (generally 3 or 4) to 6 months. In order to reach this objective three experiments were performed. During all experiments high mortalities (mostly due to fungal infections) were observed. In previous studies also high mortality rates of wild breeders were observed after capture and in the first phase of captivity conditions. The present results indicate that these mortalities were related to a weakness in immune defences, such as the decrease in temperature (winter syndrome).