Figure 7. Ovary of Murmansk herring Nov. 6, 1938, Finmark Bank, 

 mm., age 6+, stage IV. x 67. 



Length of fish 246 



How long a time the roe will remain in stage VI, may be found by determining the time 

 needed for the eggs left from the previous spawning to be resorbed, and the empty follicles to dis- 

 appear. 



Immediately after spawning the roe is of a purple color, by degrees changing into red, rosy, 

 and at last into a lig^t yellow color. The histological investigation indicates that the change in color 

 is caused by the gradual resorption of the empty follicles . Herring with roe in stage VI occur in 

 April , May and June . 



The total spawning in herring is proved by the histological investigation. The occurrence 

 of herring in stage V during a longer period of time, and in different areas of the Barents Sea in- 

 dicates that the different schools do not mature simultaneously . The occurrence of herring in stage 

 V during a comparatively long period cannot be explained by the spawning in batches, as the histo- 

 logical investigation clearly indicates that the spawning is total. This is characterized by a simult- 

 aneous ripening of all the ovocytes which are going to be extruded during the next spawning. From 

 the occurrence of herring in stage HI the time of next spavraing can be determined approximately. 



The transitional stages. In practice, it is often difficult to decide the stage of some individ- 

 ual. In such cases the use of transitional stages is necessary, i.e., II-III, III-IV, and so on. (D. 

 Talin used the scale of Kiselev for the Don herring, using the stage IV-V to characterize the gonads 

 in the transition from maximtun of maturity to the beginning of spawning). 



There are two reasons for the use of transitional stages. Firstly, there is a continuous 

 transition from one stage to another, secondly, with the present scale of maturity, based on sub- 



219 



