Survival of Freshwater Drums Released from Lake Erie Commercial Shore Seines

Abstract

Catch size and oxygen concentration affected survival of commercially seined fresh-water drums Aplodinotus grunniens intended for release back to Lake Erie or for live transport to fishing ponds. Survival was inversely related to the time that fish in beached seines were exposed to deoxygenated water and, in general, survival was greater in smaller catches (1-3 tonnes) than in larger catches (7-30 tonnes). Dissolved oxygen (DO) concentrations declined drastically with the length of time fish remained in the beached seine and with increased catch size. Fish sampled from water with more than 6 mg DO/L had greater survival than fish taken from water with 2-6 mg DO/L; oxygen levels below 2 mg/L were associated with high mortality. Survival was not related to water temperature (14.5-19.5°C), and large fish were less affected by seine capture than were smaller fish. Maintenance of oxygen levels in the seine by encouraging water flow into the beach seine, direct delivery of oxygen, or less crowding of captured fish are proposed to improve survival of released fish. A model to predict the survival of released fish indicated that approximately 85% of the freshwater drums die after release from Sandusky Bay (Ohio) shore seines during the spring fishing season.