Salmonid fishes represent an important component of the fisheries in Poland as well as in other countries. The stocks of salmonid fish in the natural waters depend to a large extent on the feeding conditions of the streams into which their larvae or fry are released. Rearing the fry on artificial diets prior to stocking, in a controlled environment, leads to a higher stocking success, primarily due to better survival rates compared with the free swimming fry. There is a hypothesis, however, that rearing the sea trout fry on a natural diet in the form zooplankton could considerably improve the chance of survival in the stream. Natural diets, contrary to the artificial ones, enhance the fry hunting instincts, which may often become a critical survival factor. This report presents the results of rearing sea trout fry on natural diets, which has been compared with artificial feeding as well. The food reservoir comprised the zooplankton collected from the outlets of an artificial and a natural water body.

15-30