Features of feeding for pacific herring <i>Clupea pallasii,</i> walleye pollock <i>Theragra chalcogramma</i>, and arabesque greenling <i>Pleurogrammus azonus</i> in Peter the Great Bay (Japan Sea) in summer season

Qualitative and quantitative indices of feeding and competitive relationships are investigated for pacific herring Clupea pallasii , walleye pollock Theragra chalcogramma , and arabesque greenling Pleurogrammus azonus on the data of bottom trawl surveys conducted over the shelf and upper continental slope of Peter the Great Bay in June-September of 2002-2009. Daily rations of these species in summer are estimated as 4.5, 3.0 and 4.3 % of body weight on average, respectively. The diet depends on their bathymetric distribution and structure of prey: generally, the portion of plankton and nektobenthos reflects the species ability to dwell beyond the bottom and changes from 66.9 and 32.1 % for herring and 45.2 and 46.9 % for pollock to 30.2 and 31.8 % for greenling. The rest of the greenling diet is presented by benthic invertebrates (24.8 %) and nekton (13.2 %). Mysids are the main common diet component for all three species, their portion in the herring and pollock diets is extremely high in Peter the Great Bay comparing with other habitats of these species, obviously because of high abundance of mysid shrimps and low concentrations of large-sized zooplankton (particularly euphausiids) in the Bay. Role of the considered species in demersal ichthyocenosis of Peter the Great Bay is not high enough for food competition between them, taking into account their active seasonal migrations and low stocks of herring and pollock in recent times

Feeding and food relations of mass species of sculpins (Cottidae, Pisces) in Peter the Great Bay (Japan Sea) in summer

Feeding and competitive relationships are considered qualitatively and quantitatively for 9 common species of sculpins (Cottidae) on the data of bottom-trawl surveys of the shelf and upper continental slope of Peter the Great Bay conducted in June-September of 2002-2009. Most of these species are facultative predators (elkhorn sculpin Alcichthys elongatus , blackedged sculpin Gymnocanthus herzensteini , plain sculpin Myoxocephalus jaok , snowy sculpin M. brandti , and great sculpin M. polyacanthocephalus ), two of them are euryphages (thorny sculpin Icelus cataphractus and graypurple sculpin G. detrisus ), and two other are benthophages (antlered sculpin Enophrys diceraus is benthophagous polyphage and thread sculpin G. pistilliger is benthofagous worm-feeder). Daily ration of these species is estimated as 2.4-3.6 % of body weight, with exception of antlered sculpin that is distinguished by lower feeding intensity (on average 1.0 % per day) due to features of its physiology. Food competition between sculpins is estimated as very low, at least in summer feeding season. Cases of significant overlapping of trophic niches noted for the predatory species, as common consumption of echiuran Echiurus echiurus and snow crab Chionoecetes opilio , are reasoned by high abundance and availability of these prey, not by real competition