Stress response associated with hatchery conditions in developing chum salmon (oncorhynchus keta).

To assess the impact of hatchery techniques on the stress response of Chum Salmon, developing fish were subjected to treatments of formalin, low-medium-high densities, thermal shock, and mechanical distress. Mean cortisol levels for formalin treated eggs immediately increased ~350% and remained elevated for 60 minutes until returning to control treatment levels. Mean cortisol levels differed significantly between formalin treatment and control at all density levels. Both mortality rate and mean cortisol differed significantly between low, medium, and high densities. Shock and pick, as well as transport of salmon fry, was mimicked with mechanical distress and cortisol levels did not increase until mechanical distress continued for 90 minutes whereby cortisol concentrations increased ~295% above control levels. These results should help identify stress responses during early life stages of chum salmon as well as identify potential sources of anthropogenic stress associated with hatcheries.