Current Data on the Taxonomic Composition and Distribution of the Trawl Macrozoobenthos in Russian Waters of the Sea of Japan

Abstract

A complex bottom trawl survey (430 stations) was conducted over all of the shelf and continental slope (within a depth range of 10–750 m) in the Russian waters of the Sea of Japan from April 1 to July 8, 2015. A total of 211 taxa of invertebrates were recorded from trawl catches. The most widely represented of them were starfish (36), shrimps (32), gastropods (27), bivalves (23), brachyuran and anomuran crabs (11), polychaetes (11), coral polyps (10), and sponges (10). The total recorded biomass of macrozoobenthos in benthic biotopes of the northern Sea of Japan reached 1 572 500 t (136 600 t in Peter the Great Bay, 341 500 t in the Southern Primorye area, 686 000 t in the northern Primorye area, and 408 400 t in the Western Sakhalin subzone), which is higher than the mean long-term level. The total stock of commercial invertebrates was estimated at 630 000 t. Its largest portion (265 200 t, or 42.1%) was concentrated in the northern Primorye area (western Tatar Strait). The mean specific biomass of the trawl macrozoobenthos constituted 13.5 ± 1.1 g/m2 (including 6.3 ± 0.5 g/m2 of commercial benthic species). The most abundant groups were brittle stars (372 200 t), brachyuran crabs (231 600 t), anomuran crabs (48 700 t), shrimps (226 900 t), sponges (182 900 t), sea lilies (167 500 t), starfish (77 200 t), sea urchins (59 000 t), and bivalves (49 500 t). The vertical distribution of the total benthos and its commercial portion was characterized by maxima in the upper shelf (10–50 m) and within a depth range of 300–400 m. In the northwestern Sea of Japan, 18 biocenotic complexes of trawl macrozoobenthos were identified. The largest areas were occupied by the group of the sedentary seston-feeding sea lily Heliometra glacialis (biomass 5.5 g/m2, depth range of 104–692 m, 131 stations), the group of the polyphagous snow crab Chionoecetes opilio (4.4 g/m2, 27–552 m, 71 stations), the group of the mobile seston-feeding basket star Gorgonocephalus eucnemis (6.6 g/m2, 58–372 m, 40 stations), and the group of the polyphagous pale yellow sea urchin Strongylocentrotus pallidus (4.7 g/m2, 17–351 m, 40 stations).