to 16-60 mg/m3). After the descent of Calanus , the main bulk of the plankton of the upper strata 

 in the central regions of the Norwegian Sea was composed of organisms, which are not satisfactory 

 food for large herring, namely: the young of the jellyfish, Aglantha digitalis, together with an abun- 

 dance of the slimy radlolaria Collozoum , and the small Copepoda - Oithona similis and Pseudocal- 

 anus elongatus . 



pre -spawning 

 3. red Calanus 



Figure 11. Distribution of the main plankton complexes in June, 1954. 1 



accumulations of j^alanus; 2. nauplii and young of Calanus; 



at the surface; 4. red Calanus descended into the deep; 5. Phaeocystis ; 6. 

 diatoms; 7. Calanus hyperboreus ; 8. jellyfish. (See Figure 8). 



Apparently lacking sufficient food, the herring of the older age groups quickly passed through 

 the central regions of the Norwegian Sea. They appeared in the area of Mohn's Threshold one 

 month earlier in 1954 than in 1951 and 15 days earlier than in 1953 (according to data by Marti). 



126 



