Plasma Cortisol Stress Response of Juvenile Chinook Salmon to Passage through Archimedes Lifts and a Hidrostal Pump

Abstract

We examined the cortisol stress response of juvenile chinook salmon Oncorhynchus tshawytscha to passage through Archimedes lifts and a Hidrostal pump operating at speeds used for commercial water delivery. In 1998, plasma cortisol was measured for Archimedes-passed salmon at 0, 1, 3, 6, 12, and 24 h after passage. Concentrations among treatment groups did not differ significantly from those among control groups, which were treated similarly but not passed through pumps. In 1999, cortisol was measured at 0, 1, 1.5, 3, 6, and 12 h after passage for both pump types. Concentrations did not differ significantly between treatment and control groups for the Archimedes lifts. A relatively small pump effect, less than 50 ng/mL of cortisol, was measured for the Hidrostal pump 3 h after passage. A handling control comparison demonstrated that much of the measured stress response was due to capture, confinement, and transport of fish before insertion into pumps. In general, these results indicated that pump-induced physiological stress in juvenile chinook salmon was relatively low.