Physiological Stress Responses of Cutthroat Trout to Loading by Fish Pump, Conveyor, or Dip Net

Abstract

The physiological stress response of cutthroat trout, Oncorhynchus clarki, to three methods of loading into truck tanks for transport was evaluated. All loading methods caused a significant decrease in chloride and increase in plasma cortisol levels, relative to the baseline sample of unstressed fish. Based on plasma chloride changes, the conveyor method appeared the least stressful to the fish, while fish pump and dip netting were not significantly different from each other. Differences in plasma cortisol responses suggested that the conveyor and dip net method were less stressful than the fish pump. Plasma glucose concentrations in the fish were not elevated after loading and did not differ among loading methods. Overall, the conveyor method was the least stressful method of loading, but the differences were not sufficient magnitude to preferentially use one method over another.