168 



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



There are two annual maxima in the feeding of the haddock (Fig. 68) : 

 the larger one in spring at the expense of caplin, which approach the coast 

 for spawning, and its ova (index of repletion 256), and the autumn one, at the 

 expense of benthos (the repletion index in the open sea is 180). In the intervals 

 between the two maxima the repletion index of the stomach decreases to 40 

 to 45. The 'infauna-bottom feeders' are the best food for haddock ; 'epifauna- 

 seston feeding' (Zatzepin's terms) biocoenoses are of secondary importance 

 in the haddock's nutrition (Fig. 69). 



Fig. 68. Annual course of feeding of haddock in the Barents Sea 



(Zatzepin, 1939). 1 Mean repletion index in coastal area of Murman 



Peninsula. 2 Same for open Sea. 



Nutrition of other benthophages. As regards the other benthos feeders the diet 

 of the long rough dab (Hippoglossoides platessoides) (V. Brotzkaya and I. 

 Komarova), the only flat-fish species, was examined most thoroughly. It is a 

 typical inhabitant of the lower Arctic sub-region, widely distributed in enorm- 

 ous numbers throughout the Sea. Hippoglossoides platessoides feeds mostly on 

 ophiura (Ophiura sarsi, O. robusta, Ophiocten sericeum, Ophiopholis aculeata) 

 and the mollusc Pecten groenlandicus. Fifty-three per cent of the contents of 

 the stomach of the dab consists of benthos (except crustaceans). Fish is also 

 very important in its diet (35-4 per cent); Triglops pingeli, cod, haddock, 

 Boreogadus saida, caplin and herring are most commonly found in its sto- 

 mach. Pelagic forms (7-5 per cent) Panda/us borealis and bottom crustaceans 

 (4 per cent) are of secondary importance in the diet of the dab. Benthos is 

 markedly preponderant in the diet of a young dab (under 25 cm), while with the 

 adult one fish and benthos are in the food in almost equal parts. The dab's 

 food may change considerably in different areas, thus, on the Gusinaya bank 

 it feeds almost exclusively on benthos, while in the Persey and Murman 

 shallows fish forms 75 to 80 per cent of its diet and in the central shallow 60 

 per cent of its food consists of pelagic crustaceans (Pandalus borealis). 



