164 



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



feeding place, the highest indices of repletion of its intestines coincide with 

 low temperatures (from -f 1° to — 1°) or almost zero. 



The cod's characteristic range of feeding is already established when it is 

 25 cm long. 



Western Fishery 

 Grounds 



Central Fishery 

 Grounds 



Eastern Fishery 

 Grounds 



Fig. 65. Diagram of food cycle of Barents Sea cod (Zatzepin and Petrova, 1939). Con- 

 tinuous lines — immature cod ; broken lines — mature cod ; / Summer fattening ; // 

 Main autumn feeding ; Ilia Period of lesser feeding during spawning migrations ; 

 Illb During spawning; IV Spring fattening in (a) central and (b) western fishing 

 regions ; V Period of forced starvation. Areas of circles correspond to repletion 

 indices. 1 Plankton organisms; 2 Euphausiaceae ; 3 Prawns; 4 Bottom-living 

 crustaceans ; 5 Other bottom-living animals ; 6 Herring ; 7 Caplin ; 8 Cod and had- 

 dock young; 9 Arctic cod; 10 Other fish. 



For some sea areas, where cod gathers in dense shoals, migrating from one 

 region to another, an inverse ratio has been recorded between the index of 

 repletion of its intestines and its likelihood of being caught. In other areas, 

 however, abundant cod yields were taken during its periods of intensive feed- 

 ing. The cod's daily feeding routine of the Barents Sea is not expressed pre- 

 cisely (E. Zadulskaya and K. Smirnov, 1939). The hours of greatest repletion 



