Results of the bottom trawl survey conducted over the shelf and continental slope in the Russian waters of the Japan Sea from Peter the Great Bay to the Soya Strait in the period from March 31 to July 8, 2015 are presented. Species composition, biomass and spatial and bathymetric distribution of benthic and demersal fish are determined. Bulk of the biomass (> 90 %) was formed by 4 families: gadids, flounders, sculpins, and herrings. The species structure varied considerably by areas: pollock and plain sculpin dominated in Peter the Great Bay, pollock and sealyeye plaice - at southern Primorye beyond the Bay, herring - at northern Primorye, and sealyeye plaice and longsnout flounder - at southwestern Sakhalin. The highest density of distribution was recorded in Peter the Great Bay at the depths 500-700 m - 26.8 t/km², with domination of pollock, the lowest density was at southern Primorye in the depth range of 700-800 m - 2.4 t/km² with domination of sealyeye plaice. Peter the Great Bay was surveyed in conditions of winter distribution of fish distinguished by their high concentrations at the continental slope; their shift towards lower depths was observed at Primorye coast, and almost summer type of bathymetric distribution with the high concentrations on the shelf was found at southwestern Sakhalin. The biomass of benthic and demersal fish has increased slightly in compare with the 1980-1990s.

Dynamics of demersal fish biomass is considered on results of trawl surveys conducted in Peter the Great Bay (Japan Sea) in 1977-2015. Fishery did not have a significant impact on this complex of fish species, including both fluctuating species (walleye pollock, arabesque greenling, pacific herring) and species with stable stock, because of low intensity. Annual landings in the bay were much lower than recommended volumes (TAC). However, a tendency to the total biomass decreasing was observed, accompanied with growth of the sculpins (Cottidae) portion in the ratio of species biomass. The sculpins prey on juveniles of many other species, so maybe their higher abundance was one of reasons for general depletion of the benthic fish community. Other predators, as marine mammals, were not abundant in Peter the Great Bay. For rational resource management, the fishery impact should be distributed proportionally between populations, taking into account their state, so both traditional commercial objects and predators with growing abundance should be landed. This ecosystem approach requires permanent monitoring to all groups of fish species.