Juveniles of pink and chum salmon in the southern Okhotsk Sea in their late marine stage (August-October 2012). Distribution, feeding, patterns of growth
Аннотация:Ontogeny of one generation of pink and chum salmons is described for the period after their juveniles redistribution from coastal waters to deep-water areas in the central and southern Okhotsk Sea in August-November, 2012. The juveniles fed very intensively in August when their diet had about 85 % of proteins and 15 % of lipids due to prevalence of hyperiids and oikopleuras with low fat content. Their growth rate was high at this stage, and energy expenditure on growth took about a half of the ration (56-63 % for pink salmon and 40 % for chum salmon). The feeding intensity became lower in October, but caloric content of the food increased because of partial replacement of its protein fraction by lipids, which content exeeded 75 %. Linear growth rate decreased in October in 3.8 times for pink salmon and in 1.8 times for chum salmon, it took 21-27 % of food energy for the pink and almost the same portion as in August for the chum. Both feeding activity, growth rate, and fat deposit depended on temperature. Temperature in August was more favorable for feeding and metabolic processes, in particular for pink salmon that was able to consume daily up to 1/10 of its body weight and spend > 50 % of the energy for the growth, but water cooling in October caused lesser feeding, lower metabolism, and slower growth.
