THE BARENTS SEA 



171 



bottom crustaceans, as for example Gymnacanthus tricuspis, Icelus bicornis, 

 Aspidophoroides olriki, Triglops pingeli and Lycodes pallidus. Still others 

 thrive almost exclusively on bottom crustaceans, as Myoxocephalus quadri- 

 comis, Lycodes seminudus and L. agnostus ; some feed equally on benthic and 

 pelagic organisms (crustaceans) like Careproctus reinhardti and Liparis major ; 

 and finally a fifth group lives exclusively on 

 pelagic crustaceans, as for example Gadus 

 poutassou and Ammodytes tobianus. 



Diet of herring and some other plankton-eating 

 fish. Herring, caplin, Boreogadus saida and bass 

 are the most characteristic plankton-eating fish 

 of the Barents Sea. The southwestern parts of the 

 Sea are the best feeding grounds for pelagic fish, 

 and the eastern ones for benthos feeders. In the 

 western part of the Sea even cod feeds mainly on 

 pelagic organisms and in the eastern one on 

 benthos. 



During the summer (as was shown by Yu. 

 Boldovsky, 1941) herring fattens on Calanus 

 finmarchicus, Thysanoessa inermis and 77г. raschi, 

 which form no less than 90 per cent of the zooplankton consumed by it. 

 Herring fry thrives on unicellular algae and on the larvae of various 

 animals, but when a year old it begins to feed first on Calanus and then on 

 Euphausiacea (Fig. 71). 



The dependence of the rate of growth of a herring on the plankton (B. 

 Manteufel, 1941) can be shown by comparing the amount of plankton with 

 the growth of the herring during the first year of its life {Table 76). 



Fig. 71. Mean annual 

 ranges of feeding of Mur- 

 man herring in gubas of 

 Murman Peninsula (Bold- 

 ovsky). 1 Calanus finmar- 

 chicus ; 2 Cirripedia larvae ; 

 3 Euphausiaceae ; 4 Poly- 

 chaete larvae ; 5 Others. 



Table 76 



Year 



1934 1935 1936 1937 1938 



Average plankton biomass, mg/m 3 



at the entrance to Motovsky 



Gulf in June 350 100 



Increase in length of herring in the 



first year of life, mm 8-55 7-71 



320 360 400 



8-39 908 801 



In the southwestern part of the Sea Ctenophora and Bolinopsis congregate 

 at times in huge numbers of more than 200 mg/m 3 ; they may compete with 

 the herring for food in summer. In such cases Calanus may all be consumed 

 by ctenophores and herring would move into other areas. The feeding of 

 herring proceeds most intensively in June, after which it decreases and then 

 rises again in November. B. Manteufel (1941) has established a relationship 

 similar to the one noted for cod, between the repletion of the herring and the 

 ease with which it is caught. Herring are dispersed in places where Calanus 



