Modification of Swimming Mode and Stamina in Two Stocks of Coho Salmon (Oncorhynchus kisutch) by Differing Levels of Long-Term Continuous Exercise

Abstract

Coho salmon (Oncorhynchus kisutch) smolts from two different stocks were exercised continuously for 40 d at water velocities of 0.2 (control), 1.0, 1.5, and 2.0 body fork lengths per second. Their critical velocities and swimming characteristics were determined using a Blazka-type respirometer–stamina swimming chamber immediately after training and after 2 mo of rest. Endurance increased in exercised fish compared with control groups and the improvement was maintained after the period of rest. Swimming modes in freshwater differed between the two stocks, and it is suggested that these were adaptations resulting from differing genetical backgrounds. Continuous moderate exercise modified swimming modes in seawater. Long-term low water velocity regimes before release in the ocean might be a profitable rearing strategy for the survival of coho salmon because it allows an economy of energy during their oceanic migrations and improves their homeodynamic capacity.