Impact of eddies on spatial distributions of groundfishes along waters off the northern Kuril islands, and southeastern Kamchatka (north Pacific Ocean)

Distributional peculiarities of groundfishes, inhabiting the Pacific waters off the northern Kuril Islands and southeastern Kamchatka, where three quasi-stationary eddies occur, are considered in this paper. The possible influence of eddies on occurrence of groundfishes are discussed. Existing eddies off underwater plateau and small banks in the southern part of the study area provides specific environment (bottom relief, temperature, and currents) for fish inhabitation essentially differed from that of adjacent waters. Composition of ichthyofauna, off plateau area, is very specific. There are several species widely distributed in the North Pacific that were caught only within plateau area. Some species widely distributed within the Pacific waters off the Kuril Island and eastern Kamchatka are abundant only in the area off plateau and banks. Feeding aggregations of plankton-feeders Atka mackerel and Pacific Ocean perch (these species are targets of specialized fishery) occur here throughout the year, probably related to fine foraging conditions in the enlarged plankton biomass in the area. Pelagic larvae and juveniles of some fishes, permanently dwelling the area, probably grow there until settlement. The study area serves as nursery ground for some fishes, which spawn outside the area. Currents transport pelagic larvae and juveniles of these species from main spawning grounds (eastern Kamchatka and Paramushir Island coasts) to the south. The larvae fall into eddies, inhabit these waters until settlement, feed on plateau slopes and later with increase in size start reverse migrations. Thus, eddies affect occurrence and distributional patterns of various groundfish species, having different types of life cycle.