EFFECTS OF ROUTINE HANDLING AND TAGGING PROCEDURES ON PHYSIOLOGICAL STRESS RESPONSES IN JUVENILE CHINOOK SALMON

Juvenile chinook salmon Oncorhynchus tshawytscha were subjected to han dling and tagging protocols typical of normal hatchery operations and monitored for their physiological response to stress. Treatments inclu ded coded-wire-tagging, counting, ventral fin clipping, adipose fin cl ipping, and a procedure simulating a pond split. Treatment fish were a lso subjected to a standardized stress challenge (1 h confinement) to evaluate their ability to deal with disturbances subsequent to a handl ing or tagging procedure. Circulating levels of cortisol and glucose w ere used as indicators of stress. Each of the treatments elicited very similar responses among treatment groups. Cortisol increased from res ting levels of about 20 ng/mL to about 90 ng/mL by 1 h poststress and returned to near resting levels by 8 h poststress. Glucose levels incr eased from 50 mg/dL to about 80 mg/dL by 1 h poststress and remained e levated for much of the experiment. The cortisol and glucose responses to the confinement stress did not differ over time or among treatment s. However, the confinement stress results do suggest a small but sign ificant cumulative response, indicating small residual effects of the original handling protocols. No deaths were noted among treatment grou ps.