titles . 



The absence of clearly expressed or marked zones of "blooming" in June and July and the 

 homogeneity of conditions over the entire area allowed the herring to feed or fatten over a large 

 area and hindered the formation of solid concentrations of fish. 



Figure 10. Distribution of the main plankton complexes in July-August, 1951. 1. pre- 



spawning accumulations of Calanus ; 2. nauplii and young of Calanus ; 3. red 

 Calanus at the surface; 4. red Calanus descended into the deep; 5. Phaeo- 

 cystis ; 6. diatoms; 7. Calanus hyperboreus ; 8. jellyfish. (See Figure 8). 



Since spring plankton production began earlier than in 19:i3, i.e. 15 days earlier, the main 

 bulk of the feeding plankton (red Calanus) had been destroyed Jay plankton-eating organisms towards 

 June. The specimens of Calanus that survived the carnage as the surface temperature rose de- 

 scended earlier than in previous years to depths of more than 100 m. In connection with this, the 

 amount of plankton in the 0-50 meter layer decreased to 150-300 mg/^3 (in a number of places even 



125 



