Underyearling pink and chum salmon in the western Bering Sea during the fall season (September and October 2013): Distribution, feeding habits, and growth patterns

Abstract

The ontogeny of a year class of pink and chum salmon is described for the period after the redistribution of underyearling individuals from coastal waters to deep-sea areas of the western Bering Sea in September and October, 2013. The intensity of their feeding was high; their diet included hyperiids, pteropods, and juvenile euphausiids. The metabolic costs of growth reached only 20% of the consumed food, which indicates significant energy costs for locomotion; moreover, as the body size increases, the level of metabolic functions rises at a decreasing rate, which causes the body growth to slow down and food consumption to decrease. The main items in the diet of underyearling salmon are characterized by a low content of dry matter, low lipid content, and, consequently, a low calorie content, i.e., underyearlings mainly consume protein-rich food with a low fat content. The chemical composition of the tissues almost did not differ between underyearling pink and chum salmon. Both species typically had a low fat content in their muscles. Thus, fat is not accumulated at this stage of ontogeny; all energy that is obtained with food, after being used for locomotion and metabolism, is spent for linear growth.