Figure 5. Quantity -weight analysis of the food of the Atlantic -Scandinavian herring in 1955. 

 Symbols: M. small herring in the sample (1950 year class); C. mixed herring 

 (large, medium-sized, and small); K. large herring in the sample . The day of 

 the month on which each sample was taken is shown as the mmierator, the month 

 as the denominator. 



The plankton was analysed viaually— . When the food and plankton are being compared, it 

 must be remembered that the Nansen net is not a perfect catching instrument and is a poor means 

 of catching the more active forms of plankton, such as the Eufrfiausiacea, fish larvae, young fish, 

 and other organisms which form a substantial portion of herring food but which are hardly ever 

 found in samples of plankton collected with a Nansen net. For instance, in February 1951 and 1954, 



1_/E. A. Pavshtiks (9) describes the rules governing the distribution of those plankton organisms 

 which serve as food for the herring. 



155 



