though individual specimens show that the quantities of Euphausiacea and Themisto are increasing. 



Food of the Herring throughout the Year 



According to the data obtained from the field analysis of the food of the Atlantic -Scandina- 

 vian herring, the lowest average mark for stomach fullness for all the years in which observations 

 were made is that for the winter months of February and March; it increases slightly in April and 

 May, while the maximum is reached in June and July, i.e. the greatest number of feeding individ- 

 uals are found during this season. The average stomach fullness index decreases from August on- 

 wards; this is due to the increase in the percentage of empty stomachs and to the decline in the 

 weight of food in the stomachs of feeding herring (Table 4, Figure 1). 



The field observations on the feeding rate of the herring in June and July 1955 were analysed 

 separately for the different age groups . For this, the analysis of the younger herring which had 

 spawned only once (the quantities of which were greatest in the commercial catches at this season) 

 was carried out separately from that of herring which had spawned more than once. 



The results of the analyses are given in Table 5, from which it will be seen that no differ- 

 ences in the rate of feeding according to age groups were observed during the months in question. 



The stomach fullness indices for the summer months in different years are given in Figure 

 2 in the form of circular diagrams, which reflect fairly clearly the quantitative and qualitative vari- 

 ations in the herring food. 



The average index for the different months is given under each circle . The sectors of the 

 large circle correspond to the quantities of the different food types; the small circle in each dia- 

 gram indicates the ratios of feeding (black sector) and non-feeding (white sector) fish. 



EHstribution of the Herring and Variations in the 



Composition of its Food 



During the winter, the maturing herring concentrate in the south-western part of the Nor- 

 wegian Sea. From mid-January, the pre -spawning shoals make their way to the spawning grounds, 

 where they remain for some time, and the majority of the herring have finished spawning by mid- 

 March . After spawning, the herring is in a very exhausted condition and goes off in search of food, 

 travelling great distances to plankton-rich areas . 



In the area of the Faroe -Shetland chaimel and of the Viking Bank (in the Atlantic current), 

 pre -spawning congregations of Eupiiausiacea ( Meganyctiphanes norvegica ) begin to form in the sur- 

 face layer as early as February . 



The material at our disposal enables us to draw certain conclusions regarding seasonal 

 variations in the food of the herring. 



Figure 3 gives data on the qualitative composition of the food of the herring in the Norwe- 

 gian and Greenland Seas for the period 1951-54 during its migrations (Table 6). 



In the years during which there is a mass development of food organisms, a certain number 

 of herring feed actively before the onset of spawning. Thus, in February 1951 and 1954, in samples 

 1 and 2 (Figure 3), the stomachs of individual specimens of mature herring at stage V or V-VI l' 

 1/ V and V-VI correspond to the pre-spawning stages in the development of the gonads . VI is 

 the spawning stage . 



147 



