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



grey mullet. Some fish, for instance hardtail and Gadus (gaidropsarus) medi- 

 terraneus, have a mixed diet. 



Table 189. Composition of the food of three species of Black Sea herrings as a 



percentage 



Higher Lower 



Fish crustaceans crustaceans Sea-weeds 



C.pontica 74-1 9-7 — 



C. maeotica 95-4 3-4 — — 



C. tanaica — — 49-7 50-3 



The ratio of planktophages to benthophages in the Black Sea is the 

 exact reverse of that in the Sea of Azov. The pelagic carnivores are hardly 

 represented at all. Azov predatory fish feed mainly on small bottom-living 

 fish, as, for example, pike-perch. Marti's idea that considerable development 

 of pelagic carnivores is impossible in the Sea of Azov because of the low 

 transparency of its waters is very interesting. In the Black Sea, however, 

 large accumulations of pelagic carnivores shoal in the region near the Kerch 

 Straits in autumn, as if waiting for the anchovy to come out of the Sea of 

 Azov. 



V. Wodjanitzky (1941) notes that the ratio of pelagic to benthic fish in the 

 commercial yields is 7:1. Actually this ratio of the two groups of fish is even 

 higher, since fishing in the open parts of the Black Sea is still undeveloped. 



Since the Black Sea plankton biomass is two or three times smaller than 

 that of benthos, the cause of this sharp predominance of pelagic fish over the 

 benthophages should, in Wodjanitzky's opinion, be sought in the fact that 

 'with its small biomass plankton is highly productive throughout the year, 

 doubling its biomass several times . . . and in the food-chain plankton-fish 

 we have, undoubtedly, a more complete and direct utilization of substances 

 for the building up of commercially useful organisms than in the food-chain 

 benthos-fish, as in the complex chain of feeding on benthos and the feeding 

 of benthos we find a large number of dead ends which finish up in useless 

 organisms'. Many benthos-eating fish feed in the northwestern part of the 

 Black Sea. 



L. Arnoldi and E. Fortunatova (1941) have carried out a comprehensive 

 investigation of the biology and physiology of the nutrition of small, bottom- 

 living coastal-water fish. They have elucidated the standards of the daily 

 consumption of food, the feeding intensity, the gain in weight for various 

 standards of feeding, the rate of digestion, the assimilation of food, etc., and 

 the changes in all these indices with the season and with temperature. 



Fisheries. The situation and the prospects of development of the Black Sea 

 fisheries reflect in a most characteristic manner some peculiarities of the 

 distribution of fauna in it. 



Before 1939 the yield of our fisheries in the Black Sea was about 500,000 

 centners. The yield of those of other countries was about 360,000 centners 



