Ivanova (23) observed ovocytes in different phases of development in the ripe ovaries of the 

 Brazhnikov herring and concluded that this species had a distinct, partial spawning. 



Having stated that both total and partial spawning exist, with real examples from two genera 

 of herring, we shall mention another feature in the spawning, namely, the character of the extru- 

 sion of the ripe eggs from the ovaries. As already mentioned, the Murmansk herring has a total 

 spawning; but the character of the spawning in the oceanic herrings has been unsufficiently treated 

 in the literature . From the analysis of one sample of spawning herring from the area near Ring- 

 vass^^y we determined how the Murmansk herring spawns the ripe eggs. With only one sample at 

 our disposal, we cannot, of course, answer the second, but not less important question: when are 

 the ripe eggs spawned, and how many spawning intervals may exist. We shall once more mention 

 that, regardless of how many extrusions of eggs there may be, there is in all one single portion of 

 ripe eggs in the ovary, and they are all extruded during the spawning period. 



An analysis of ovaries in the maturity stage V gives an idea of the character of spawning in 

 the Murmansk herring. In the individuals of a spawning school the extrusion is proceeding in var- 

 ious ways; a total extrusion is observed in some individuals, a partial one in others. In addition, 

 each ovary discharges the ripe eggs unequally. We may therefore restrict ourselves to the dis- 

 cussion of the various moments of extrusion of one single portion of ripe eggs in one certain year. 



For the stock of Murmansk herring as a whole, the spawning lasts very long, but in the 

 single individuals the spawning is total and rapid. The long duration of the spawning in the total 

 stock (1 1/2 - 2 weeks) is caused by the non- isochronal ripening of the sexual products in the indi- 

 vidual populations. For this reason all the herring do not come to the spawning places at the same 

 time. This means evidently an adjusting of the competition for spawning places, and for the feed- 

 ing of the young after the spawning. In the Caspian herring, the partial spawning is an adaption for 

 the conservation of the species by increasing the fecundity, an adaption which is widely distributed 

 in nature . 



Fecundity 



There are very few data on the fecundity of the Murmansk herring, except from Eslpov (19), 

 but he had only very limited material at his disposal (Table 1.). 



TABLE 1. THE FECUNDITY OF THE MURMANSK HERRING (AFTER ESIPOV). 



The herring laboratory of the PINRO has placed at our disposal material for a study of the 

 fecundity of the Murmansk herring. We calculated the number of eggs in a weighed sample, and 

 the total fecundity was computed by weig^ng the ovaries . 



206 



