Handling as a factor in mortality of trout with or without furunculosis

Mortalities of brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Salmo gairdneri) in 1978 and 1979 were significantly higher in clinically diseased than in subclinically diseased or healthy fish in both years. Mortalities in diseased fish within 24 h after sampling were not statistically different from those in specific-pathogen-free controls; however, the crowding offish lots for stocking resulted in significantly higher mortalities in furunculosis-infected brown trout in 1979. Crowding and handling for stocking thus caused higher mortality in diseased fish than just sampling. Healthy trout were able to tolerate more handling stress.