Specific features of feeding and trophic status of mass species of the family Macrouridae in the northwestern part of the Pacific Ocean

Based on materials of expeditions of TINRO-Center into the northwestern part of the Pacific Ocean, we analyze data on feeding of mass species of Macrouridae. Grenadiers Albatrossia pectoralis and Caryphaenoides longifilis are consumers (in order of importance) of cephalopods, fish, and crustaceans and C. acrolepis and C. cinereus are consumers of crustaceans, cephalopods, and fish. All grenadiers demonstrate age-related variability of food composition from polychaetes and small crustaceans to fish, squids, and large crustaceans. The change in dominant prey of A. pectoralis occurs upon its reaching a length of 50?C60 cm, and that in C. cinereus occurs upon its reaching a length of approximately 50 cm. Changes in the feeding spectra from prey of in- and epifauna to macroplanktonic and nektonic organisms indicate the widening of trophic niches of grenadiers in ontogenesis. The spatial position of each species of grenadiers correlates with its size: the smaller the species, the less it is separated from the ground trophically. According to the type of feeding, C. cinereus is a bentho-planktonic feeder, A. pectoralis is a nekto-benthonic feeder, and C. acrolepis occupies an intermediate position between them. According to the calculated values of trophic levels, the studied species are (in order of decrease) A. pectoralis, C. acrolepis, and C. cinereus; the trophic level of C. longfilis can be preliminarily assessed as close to that of A. pectoralis.