Themisto abyssonim, Euphauslacea and Oikopleura labradorlensis were encountered, at times, in 

 the stomachs of herring. 



Sexually immature herring and herring that spawned for the first time (their spawning ends 

 much later than is the case for herring of older age groups) keep to waters with a temperature of 

 4-6° (and higher). They feed in the central regions of the Norwegian Sea and do not proceed far to 

 the north . 



Large herring (29-35 cm .) begin their feeding or fetteolng early In spring, i ,e . prior to the 

 development of new generations of Calanus . While feeding upon the adult crustaceans- -their num- 

 ber is small --that had wintered, the herring accomplish long migrations. In some years they go 

 far to the north. Often, when searching for large and easily accessible food, the herring enter the 

 mixed waters near the cold East Greenland current. We observed in June, 1955, schools of large 

 herring that had consimied great numbers of Calanus hyperboreus in waters with a temperature 

 below 2°. 



The observations made in 1954-1955 speak of the abundance of large plankton in cold waters 

 ( Calanus hyperboreus and Themisto libellula) . The concentrations of reproducing Calanus hyper - 

 boreus are formed in the surface layers of the water with a temperature of +3 to -1 (and even 

 lower). Especially large nimibers of these crustaceans were encountered north of Jan Mayen and 

 Bank 600. While searching for food, the herring in Jime entered waters with a very low temper- 

 ature from +1.6 to +3.5°. The captain of "SRT M-1" (Medium Fishing Trawler Ml) "Korablestr- 

 oitel, " Comrade Dmltriev, caught herring in waters with a temperature of +1.8 . Such catches of 

 herring that feed in polar waters do not represent isolated cases. In 1947, the E/S "Cachalot" 

 caught herring at the edge of the ice near 78 degrees north latitude at a very low temperature. 

 From June 7-20, 1954, a group of boats of the North-Atlantic Herring Expedition caught herring at 

 a temperature below 3 degrees on the surface (but, at a depth of 25 m. in this region, the Atlantic 

 waters had a temperature of 3-4 degrees). In July, after the waters of the East Greenland current 

 had been warmed by solar radiation to a temperature of 3-5 degrees, it is quite possible for herring 

 to contiilue their feeding in actual polar waters. Towards August, the herring finish their feeding 

 in polar waters; for even there the search for food is getting more difficult. There is a develop- 

 ment of Phaeocystis and of diatoms; the spawning of Calanus is about to end and its tiny nauplii 

 occur in the plankton. The adults of Calanus die after spawning. The feeding of the herring comes 

 to an end; they turn southward and begin to enter the warm waters of the Norwegian current. The 

 number of herring with empty stomachs is increasing (in July 18%, in August 40%), since they can 

 not find sufficient food. 



At about this time, the amount of surface plankton is sharply diminished. Furthermore, the 

 bulk of plankton consists of tiny Copepoda; Pseudocalanus elongatus , Olthona slmllls, Oithona 

 atlantica , Onceae borealls and the jellyfish, Aglantha digitalis . Peridlneans are developed, which 

 cause a slight "blooming". Tiny Copepoda are rarely eaten by large herring. For this reason, 

 plankton--by the end of August — ceases to Influence the distribution of herring. 



Thus, on the basis of eig^t years of observations on the development of plankton and the 

 movements of schools of feeding herring in the Norwegian and the Greenland Seas, we have come 

 to the following conclusions: 



1 . The life cycle of Atlantic -Scandinavian herring is very closely related to plankton dy- 

 namics in the Norwegian and the Greenland Seas . 



In connection with the fact that the food supply of herring changes radically when the biolog- 

 ical seasons change (Figure 6) this species endued in the course of its historical development the 

 ability to make annual feeding migrations, which make it possible to use to the fullest extent, when 



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