Trophic groups of the sculpins (Cottidae) in the waters near Kamchatka

Sculpins (Cottidae) is one of the most characteristic families of fish of the North Pacific ocean, many species of which in the far Eastern seas have a fairly high number and biomass. They play a significant role in bottom ichthyocene as predators and potential food competitors of commercial fish. Such numerous species as great sculpin Myoxocephalus polyacanthocephalus, plain sculpin M. jaok, yellow Irish lord Hemilepidotus jordani, purplegray sculpin Gymnacanthus detrisus and armorhead sculpin G. galeatus are objects of coastal fishery. Based on the comparison of feeding spectra of 27 species of sculpins (Cottidae), six trophic groups of these fishes - ambuscade predators (4 species), benthoichthyophages (4 species), nektobenthoichthyophages (2 species), benthophages (8 species), nektobenthophages (7 species) and benthomacroplanktophages (2 species) are identified in the waters near Kamchatka. Representatives of each of these groups differ in the type of food, composition and size of food organisms. The main food of ambush predators is fish and crabs, basic forage objects of the species of benthoichthyophages trophic group are 2-3 groups of bottom and near bottom crustaceous (Cirripedia, Amphipoda и Decapoda) and juveniles of fishes. Species of nektobenthoichthyophages trophic group feed on different benthic organisms, juveniles of fishes and shrimps of Thoridae family. Most species of benthophages trophic group consume mainly different Polychaeta, Amphipoda and small Decapoda, while in some species of this group (armorhead and threaded sculpins), certain food specialization is observed. Forage objects of nektobenthophages are both typical benthic organisms and invertebrates inhabiting near- bottom layer of water (Mysidacea, small shrimps, hydroid jelly-fish and Ctenophora), and benthomacroplanktophages, together with typical benthic organisms, consume plankton crustaceous (mainly, Thysanoessa raschii) concentrating in near- bottom layer of water.