816 BIOLOGY OF THE SEAS OF THE U.S.S.R. 



As may be seen from the lists of the mass forms given, the fauna of Shelek- 

 hov Bay has on the whole an Arctic aspect (N. Vinogradova, 1954), boreal 

 forms being predominant in the southeastern part of the Bay (Venericardia 

 borealis ovata, V. crassidens, Crepidula sp. and others); and Arctic-boreal 

 and lower Arctic forms in the northwestern part of it (Macoma calcarea, 

 Leda pernula, L. minuta, Yoldia myalis, Mya truncata, Musculus substriatus, 

 Axinus gouldi and others). Arctic and high- Arctic forms are concentrated in 

 the central, deep-water part of the Bay {Macoma torelli, M. loveni, M. maesta, 

 Musculus corrugatus, Axinopsis orbiculata and others). Although this zoo- 

 geographical analysis is adduced only for the bivalves, it reflects the general 

 aspect of the Shelekhov Bay fauna well. 



Abundant material on the qualitative and quantitative distribution of the 

 bottom fauna of the most important fishery region of the Sea of Okhotsk — 

 the western Kamchatka shelf — was studied by K. Gordeeva (1948). Spacious 

 feeding grouds of Kamchatka crab, flatfish, cod and others are situated within 

 this area, which is undoubtedly one of the richest regions of life in the Far 

 Eastern Seas. The mean biomass of the whole western Kamchatka shelf 

 is 482-7 g/m 2 and the feeding part of the fauna is on the average 230 to 

 300 g/m 2 . 



The surface zone of water heated up to 1 1° or 12° in summer lies at about 

 50 to 70 m. The cold intermediate layer is situated at a depth of 70 to 1 50 m 

 (temperature down to — 1-8°). The lower part of the shelf and the edge of the 

 bathyal (150 to 250 m) have a temperature above freezing point; crabs 

 migrate there for wintering. 



The most characteristic forms on the sand soil are: the large Mollusca 

 Siliqua media, Tellina lutea, and at times Mya truncata and Spisula alascana ; 

 the worms Nephthys coeca, Travisia forbesi; the Echinodermata Echinarach- 

 nius parma ; the Crustacea Crangon dalli : below the sand on the gravel bed, 

 there are numerous epifauna organisms, such as the Actinia Halcampella; 

 the Mollusca Mytilus edulis; and the bed itself is inhabited by Mya spp., 

 Serripes laperousi and Macoma middendorfi. The oozes (50 to 120 m) of the 

 southern part of the shelf contain many bivalves (Macoma, Nucula, Yoldia, 

 Liocyma and others); Gastropoda (Cylichna, Retusa and others); and an 

 abundance of the Maldanidae ; of Echinodermata Ophiura and Holothuria. 

 Still lower down, the zone of the cold intermediate layer is inhabited by bio- 

 coenoses of the most cold-water forms such as Macoma calcarea, Nucula 

 tenuis and Leda pernula. 



Fish 



The list of fish in the Sea of Okhotsk includes, according to Rass, about 300 

 species and subspecies (P. Schmidt, 1950, with T. Rass's corrections). Among 

 them 140 species are common with the Sea of Japan, and 112 species with the 

 Bering Sea. About 85 species, i.e. 28 to 30 per cent, are endemic. 



Most of the species are cold-water ones ; however, only a few are properly 

 Arctic forms. The families Cottidae (53 species), Liparidae (43), Zoarcidae 

 (41), Pleuronectidae (21), Stichaeidae (17), Agonidae (15), Cyclopteridae (13) 

 and Salmonidae (10) are the most numerous. 



