PKOPAGATION AND GROWTH OF HERRING. 647 



riugs come to the spawuiug-places during daytime, and this is said to 

 take place particularly towards the end of their visit to the coast.^^ 



Concerning the spawning-process itself, opinions are divided as to 

 whether it continues uninterruptedly till finished, or (as with the carp) 

 goes on at intervals, the contents of the sexual organs being emptied 

 gradually. The latter opinion is advocated by Axel Bocch, who men- 

 tions a number of very plausible reasons in its favor, which, however, 

 are not altogether convincing. He even goes so far as to speak of the 

 importance which this gradual spawning process ought to have for the 

 fishermen.^^ According to information received from experienced fish- 

 ermen, two to three weeks would elapse before a school of herrings 

 had by repeated emissions ejected all the spawn and roe contained 

 in their sexual organs; but this does by no means prove that every 

 individual fish spawns at intervals. The fact that the nets sometimes 

 contain fish whose sexual organs are only half emptied is not a suffi- 

 cient proof that such fish, if left alone, would have retained the pro- 

 ducts of their sexual organs till they could find another chance to emit 

 them.^ It is quite i)robable that miscarriages take place under violent 

 shocks or when death is threatened. It must also be remembered that 

 by no means all those herrings which at one and the same time approach 

 a spawning-place also spawn together, but that a greater or smaller 

 number come near the coast which are not quite ready for spawning. 

 This circumstance may have led to erroneous or exaggerated versions 

 of actual facts. As far as known the spawning iH^ocess of the great 

 schools of herrings is one continuous act. It is certain that the herring, 

 when free, does not begin to spawn until the entire contents of the sex- 

 ual organs are so loose that the least pressure will make them flow out; ^' 

 and even if there are intervals in the spawning process these intervals 

 must be very short. 



During the spawning process the herrings are packed in a dense mass, 

 are in constant and violent motion, move their tails rapidly, press and 

 rub against each other or against the bottom, press against the nets, &c., 

 all with the obvious intention to facilitate the emptying of the sexual 

 organs.^^ It has been observed that during the emission of the milt the 

 sea-water assumes a whitish color, that a peculiar odor becomes percepti- 

 ble, and that many scales which have become loose during the process 

 rise to the surface. In net-fishing it has also been observed that the 



35BOECK " Om Silden og Sildejiskerierne," p. 59. 



36 Om Silden og Sildefiskerierne, pp. 26, 27. 



'' The products of the sexual organs begin to get loose, especially in the male fish, 

 long before spawning commences. With a practical view Br. Heincke has given an 

 excellent table of the gradual development of the sexual organs in the '^Jalireshericht 

 der deiitschen Commission zur wissenschaftlichen Untersuckung der dcutschen Meere," IV- 

 VI, pp. 68, 69. 



38 Professor Hensen, who has observed the spawning of the herring in the Sli- 

 fiord (Duchy of Schleswig), says that the roe is freely emitted by the female fish while 

 hurrying to and fro over the spawning-place. {Jahresiericht, IV-VI, p. 26.) 



