Liver Glycogen, Enzyme Activities, and Pancreatic Hormones in Juvenile Atlantic Salmon ( Salmo salar ) during Their First Summer in Seawater

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Plisetskaya, Erika M., Moon, Thomas W., Larsen, Donald A., Foster, Glen D., Dickhoff, Walton W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1994
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1139/f94-059; http://www.nrcresearchpress.com/doi/pdf/10.1139/f94-059

Our observation of very low liver glycogen concentration in 1-yr-old feeding Atlantic salmon (Salmo salar) in seawater net-pens in Puget Sound, Washington, led to studies of their metabolic status. We assessed liver glycogen concentration, activities of some hepatic enzymes involved in glycogen synthesis, depletion, and gluconeogenesis, and plasma profiles of glucose and pancreatic hormones (insulin and glucagon) in yearling Atlantic salmon before and after seawater transfer. Liver glycogen concentration in Atlantic salmon during the several months after seawater entry was much lower than in coho salmon (Oncorhynchus kisutch) of the same age in seawater. Other metabolic and hormonal indices throughout the study did not differ substantially between the two species. During their first summer in seawater net-pens, seemingly healthy, feeding 1-yr-old Atlantic salmon smolts are prone to high mortality. We hypothesize that the virtual absence of glycogen reserves in the liver makes seawater-adapted 1-yr-old Atlantic salmon juveniles particularly susceptible to stress and may contribute to high summer mortality.