Figure 10. Blomass of plankton (In mg/mS in the 0-50 m. layer in 1953. 



The boundary of the feeding area of the herring in June 1953 Is indicated by the 

 continuous and broken line . 



At first sig^t, the 1953 chart(Figure 10)does not confirm this conclusion, as the lowest 

 volumes were observed in June in the current (western branch). However, according to the herring 

 fishery survey, large numbers of herrings gather in this area in June every year (see Figures 10, 

 11, and 12) and remain here in these concentrations for a long time and eat most of the plankton. 



Influence of Temperature on Quantitative Vertical Distribution of Plankton 



Variations in the quantity of plankton also vary to a large extent with the temperature of the 

 water. 



Mass development of plankton, together with a considerable Increase in its blomass, begins 

 in the spring when the upper layers of the water start to become warmer . 



93 



