Fisheries Research Report No. 1732, 1967

Michigan Department of Conservation
Research and Development Report No. 92
Institute for Fisheries Research Report No. 1732, 1967
Mortality of Recently Hatched Bluegill Fry Due to Hydra

Michael D. Clady and Gerald U. Ulrikson

Introduction.-There are numerous accounts of predation on young fish by hydra. The majority of these incidents were observed in rearing ponds or raceways. Because of the small size of these predators, only the very young stages in the life history of the fish are affected. Eisler and Simon (1961) have summarized much of the literature on hydra as enemies of fish. Our paper describes mortalities of several broods of newly hatched bluegills, Lepomis macrochirus, caused by hydra in an artificial situation. The apparent movement of the hydra to active bluegill nests has not been described before.