1 895- ^O- 9- HYDR.-BIOL. STUDIES OF THE XORW. FISHERIES. 'I 



The same is the case with the Herring. In this instance it is 

 only the Norwegian Herring we refer to. viz., the Spring Herring 

 and the Fat Herring which move in from the sea, and not of the 

 Herrings which, through generations, have been adapted to a hfe in 

 other waters and other hydrographical conditions, such as the Baltic 

 Herring, as well as some clearly local Fjord famihes. 



The Ocean Herring too, after having gone through its pelagic 

 stage, passes the first years of its development in by the coast. During 

 the Summer, both on the West Coast and on the Fjords, for instance the 

 Christiania Fjord, one may see Herrings up to the very whar\es, and in the 

 bays. In the course of the last few years I have endeavoured to dis- 

 cover for what length of time the Herring remain under the coast, as 

 well as the age of the various sizes of fish on the whole. I have 

 preferred to use a method of investigation which has has been em- 

 plo\ed b\- C. G. JoJi. Petersen with great success. Petersen has 

 measured all sizes of the same species which he has simultaneously met 

 with, and grouped the measurements, thus found, according to the size. 

 It has thus appeared that, in respect to many kinds, one obtained well 

 defined groups, which, among themselves, corresponded in size, and 

 varied to a great extent from the other groups. These groups, presum- 

 ably, represent yearly classes. 



During the Spring Herring Fisher}-, Februar\- and March 1894, I 

 measured many (many hundreds of the captured Herrings. If one 

 groups the measurements according to size, one draws, in other words, 

 a cur\e, in which the axis of the abscissa gives the size of the Herring 

 in millimetres / measured from the end of the snout to the centre point 

 in the fork of the tail) and the axis of the ordinate gives the number 

 of the herrings which falls to each milhmètre of the axis of the abscissa), 

 so that one obtains, for instance, from a number of measurements in- 

 cluding 430 herrings, the following cur\-e. 



