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



are rich in benthos ; in winter they migrate into deeper parts, avoiding the 

 considerably cooled surface waters (P. Moiseev, 1955). 



In 1955 about 1-6 million tons offish were taken from the Sea of Japan. 

 In 1936 the total catch was considerably higher, reaching 3 million tons 

 (T. Rass, 1948), mainly owing to a much greater catch than in 1955 of sar- 

 dines (Sardinops sagax melanosticta) and pollack (Theragra chalcogrammd). 



The Primor'e is exceptionally rich, both qualitatively and quantitatively, in 

 commercial sea-weeds and in invertebrates. Among the bivalves the follow- 

 ing either are commercially significant or could become so : Ostrea gigas. 

 Mytilus grayanus, Pecten jessoensis, Mactra sachalinensis and Mya arenaria, 

 There are more than 20 species of bivalves of secondary significance. The 

 cephalopods Ommastrephes sloanei pacificus, Octopus dofleini, Paroctopus 

 conispadiceus and Octopus gilbertianus are of great commerical importance. 

 Trepang — Stichopus japonicus — has for a long time been an important item in 

 the fisheries of the Sea of Japan. 



Apart from Kamchatka crab, the decapod crustaceans Pandalus latiro- 

 stris, Sclerocrangon selebrosa, Crangon septemspinosa and some others 

 are of great importance in the fisheries of the waters of the Primor'e and 

 southern Sakhalin. Stocks of all these invertebrates are very large in the Sea 

 of Japan, and the prospects of their commerical development are immense. 



