The data on recoveries of tagged herring (Table 6 and Figure 9) are of great interest. The 

 total number of tagged specimens recaptured in 1954-1955 was approximately 20. We may now 

 state with certainty that the herring from the region situated west of Bear Island migrate into the 

 southern zone of the Norwegian Sea; that the herring move along Mohn's Threshold to the south- 

 west (herring 12 and 13); that herring from the Icelandic region migrate to the shores of Norway 

 and Viking Bank (herring No. 8 and 9). The mean speed of the movement of herring to the spawn- 

 ing grounds varies from 1.2 to 6.9 miles a day. 



Schools of feeding herring may often be observed m calm weather from the boat . We ob- 

 served particularly large concentrations of herring on July 18 and 19, 1950, near Mohn's Threshold, 

 where for more than fifty miles, hundreds of herring schools drifted towards our boat. In all direc- 

 tions towards the horizon, as far as the eye could see, we saw only herring schools. Some of 

 them were easily detectable from the rippling surface of the water. The majority of the schools 

 had clearly outlined contours resembling large triangles . The herring moving at the head of the 

 school were particularly visible. They remained continuously near the surface, frequently leaped, 

 and turned over in the air. Approaching the drift nets, the schools ceased their movements for a 

 while, then moved on. That night, the catches per drift net were 1.5-2 tons. 



Migration periods of herring vary considerably from one year to another. Thus, on June 18, 

 1941, Captain V. A. Egorov spotted herring at the latitude of Horn Sound (southern Spitsbergen). 

 In 1951, the first schools of herring were encountered at that date only at the parallel of Bear Island, 

 i.e. 200 km. farther to the south. 



As a rule, herring schools enter the region of Mohn's Threshold along the western branch 

 of the Norwegian current in the early half of June. In 1954, however, considerable concentrations 

 were located near the Bank "600" on May 26. 



The dates of the southern movement of herring also vary substantially. In 1939, throu^out 

 August and in early September, the herring concentrated in great numbers north of Bear Island, 

 whereas during subsequent years, the herring vacated that region at the end of July . The factors 

 accounting for the variations in the dates of return migrations of herring from northern regions 

 have not been sufficiently studied as yet. We have grounds to assume that the duration of the stay 

 of herring in the said regions depends on the feeding conditions . When the fry on which herring 

 feed are abundant, the herring may stay in the north for a longer period of time, whereas in the 

 case of food deficiency in northern regions during August, the herring soon migrate into the south- 

 em zones. 



The direction of migration of herring to the north and the duration of their migration are 

 determined by the preceding period of the development of herring, the age at which the herring 

 spawn and oceanographic conditions in more southerly situated regions . 



Herring of the older age groups, the schools of which form the vanguard during the move- 

 ment to the north, travel farthest north. 



Thus far, the order in which herring schools move in the southern direction remains ob- 

 scure. Since the older age groups arrive first on the spawning grounds, we may assume that dur- 

 ing the southern migration they overtake younger fish. On the basis of observations available, this 

 process occurs in October-November. 



We wish to point out that during the said period there occurs a drastic re -grouping of her- 

 ring schools. We frequently observed the marked prevalence of either males or females in the 

 catches . Males usually prevail in the schools moving at the head of the migrating concentration. 



45 



