Tumor rates and population estimates of brown bullhead (Ameiurus nebulosus) in Presque Isle Bay, Lake Erie

Tumor rate and population estimates for brown bullhead (Ameiurus nebulosus) in Presque Isle Bay, Lake Erie were monitored between 1992 and 1999. Fish were collected by electrofishing and trapnet. Skin rumor (grossly observabl e external lesions) rare decreased from 61% in 1992 to 19% in 1999. Liver t umor rate decreased from 22% in 1992 to 0% in 1999. Length-frequency histog rams, collection of young of year in seines, and field observations of repr oductively active adults indicate that the population is reproducing. Popul ation estimates from a mark-recapture index resulted in similar estimates f or 1992 and 1999. These results suggest an improvement in habitat quality a nd the general health of the brown bullhead population.