Long-term dynamics of biomass and dominant species of the bottom fish complex in Peter the Great Bay

Abstract

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.