738 



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



stenobathic forms. Horizontal movements are more difficult to explain. It 

 may only be suggested that their propagation is restricted by some chemical 

 characteristics of the medium. Moreover, it may be assumed that deep-water 

 animals have a much increased sensitivity to changes in the factors of en- 

 vironment, since they are not subject to daily, seasonal or secular variations. 



Fig. 362. Bipolar distribution of deep-water animals of the Ocean (Vinogradova). 

 1 Phascolion eutense (Sipunculoidea) ; 2 Tatianellia grandis (Echiuroidea) ; 3 Scina 

 wcgleri var. abyssalis (Amphipoda) ; 4 Munidopsis antonii (Decapoda) ; 5 Glypho- 

 crangon rimapes (Decapoda) ; 6 Nymphon procerum (Pantopoda) ; 7 Hymen- 

 aster anomalus (Asteroidea) ; 8 Kolga nana (Holothurioidea) ; 9 Culeolus shumi; 

 10 C. murrai (Ascidia). (2,000-7,300 m.) 



V. COMMERCIAL IMPORTANCE OF THE FAR EASTERN 



SEAS 

 The Far Eastern Seas are commercially very rich. They contain about 800 

 species offish and approximately 200 of these are commercial or may become 

 so (P. Moiseev, 1953). 



It is to be noted that 60 years ago fishing in Russian waters was confined to 

 river estuaries and the coastal zones. 'More than 96 per cent of the catch was 

 composed of salmon, Oncorhynchus keta, Oncorhynchus gorbusha and 

 others, which entered the river from the sea for spawning, and about 2-6 per 

 cent was herring, caught in the coastal, low-salinity areas ; the remaining yield 

 was composed mostly of Osmerus spenlanus dentex, navaga {Eleginus navaga 

 gracilis) and the Acipenseridae, also caught in the rivers' (T. Rass, 1955). Now 

 the Acipenseridae constitute no more than a third of the yield, and the fisheries 

 have mostly moved into the open sea. The Salmonidae trade, in particular, 

 has mostly moved into the northwestern part of the Pacific Ocean (Fig. 363a). 



