Winter habitat use of fishes in the Ohio River

Winter Habitat Use of Fishes in the Ohio River Benjamin Ernst Lenz Winter is a critical period during which fishes may suffer increased mortality. To identify the habitats that fishes use in large rivers during winter conditions, we electrofished six habitat types in the Belleville Pool, Ohio River. We collected the greatest diversity and numbers of fishes in low-velocity tributary confluences when water temperatures were > 4 °C. When water temperatures were < 4 °C, certain species were collected in greater abundance in faster-velocity main channel and back channel habitats while other species continued to associate with lower flows in tributary mouths. Differing habitat use between species obscures broad generalizations about when and how fishes use overwintering refuges. In an additional habitat sampled, an embayment, 85% of all fishes collected were juveniles. Centrarchids, rarely collected in the mainstem portion of the river, were one of the dominant fishes collected in the embayment. Protecting large river embayments may prove important for managing recreational sunfish fisheries. Channel catfish, Ictalurus punctatus, and freshwater drum, Aplodinotus grunniens, the most abundant fishes collected in the Belleville Pool, exhibited growth comparable to other populations in temperate large rivers in eastern North America. Conversely, white bass, Morone chrysops, growth was slower compared to other populations, possibly explaining why none of the white bass individuals collected were harvestable size. Population growth and the probability of survival of all fishes may increase by protecting and enhancing tributary and embayment habitats in large rivers during winter.