CONSIDERATION OF INDIVIDUAL FISH 103 



These herring of 1904 are so easily distinguished from those of 

 other years that the term " marked " herring may legitimately be 

 applied to them. At any rate, Hjort and Lea claim to be able to 

 trace their movements through successive years. In 1907 and up to 

 September, 1908, the marked herring were practically confined to 

 northern Norwegian waters, only occasional specimens being met 

 with elsewhere. 



In 1908 some of them made their appearance in the large herring 

 of the Romsdal district, and were taken there in the next two years. 

 In 1910 they made their first appearance among the spring or 

 spawning herring further south, off the west coast ; in this year 

 they were even found off the Faroes, the Skager Rack, the Cattegat 

 and the southern part of the North Sea. If these results be sub- 

 stantiated by future investigators, it will lead one to believe that 

 the herring performs wider migrations than had recently been 

 supposed. It must not be forgotten that opinions are sharply 

 divided as to the utility of the investigations into the rate of growth 

 of herring and other fish by the scale-examination method. 



Molander^ has recently summarised the arguments in an elaborate 

 monograph. He shows that the scales do not appear in the young 

 herring until they are 30 mm. (about 2 in.) long. The period of 

 active growth in autumn, spring and winter spawning herring 

 varies and thus affects the scales. Molander concludes that while 

 the scales increase together with the fish, the increase is not pro- 

 portionate. During the first few years the fish grow more than the 

 scales ; while in later years the scales grow more than the fish. 



' " Ur Svenska Hydrogiafisk-Biologiska Kommissionens Skrifter" {1917). 



