52 KENDALL: NEW ENGLAND SALMONS. 



fall. In this latter situation the question arose regarding whether spring and fall salmon 

 were always spring or fall fish. In some instances it was thought that tagging kelts might 

 solve the problem. 



The earUest attempts to learn something of the Ufe history of the salmon was by 

 marking and by tagging. Fish were sometimes marked by removing a fin or two, or a 

 portion of a fin. Very commonly the entire finlet known as the adipose fin was removed. 

 Tagging consisted of attaching some object to the fish such as a band or metal disc 

 bearing a number corresponding to a numbered record pertaining to the length, weight, 

 sex and condition of the fish when Uberated. In later years the tagging experiments were 

 supplemented by 'scale-reading.' 



As Calderwood says, the study of scales of late years has been the most important line 

 of investigation. While much regarding the increase in weight and length of time spent 

 in the sea between spawning periods has been learned by tagging, much more of the Ufe- 

 history has been revealed by scale study. It is said that the growth of the scale of the 

 salmon does not begin when the fish is hatched but that there is a period of between two 

 and three months during which the surface of the body has no scales. 



Calderwood (1930, p. 53) says: 'As the scales grow from their centres, the surface of 

 the body becomes speckled over with tiny discs meeting at their edges. The material 

 is then laid down so that the scales gradually cover the interstices between the discs, 

 and finally begin to overlap in a posterior direction. I have never seen any report of an 

 investigation into the reason why the overlap arises in a posterior direction, or how the 

 advantage to the fish, as it swims head first, is secured in having the scales arranged as 

 we know they come to be. It would be an interesting study.' 



One could imagine that the advantage of such an arrangement to the fish might be 

 similar to that of the arrangement of feathers on the body of a bird when it flies, and that 

 the reverse arrangement would be a decided disadvantage. 



The scale of the salmon has been found to indicate its age by lines of growth. It is 

 increased in size by additions of rings of scale substance, each addition making a circular 

 Une at its junction with the previously formed ring. If the fish grows fast the Hues 

 (sometimes called ridges or 'circuU') are widely spaced. If the growth is slow, the lines 

 are closer together. A well-fed fish grows fast. On the other hand if it feeds but Uttle, 

 the growth is slow. It is beUeved, with abundance of evidence in support of the belief, 

 that the salmon feeds but httle in the winter. Therefore the lines of growth are more or 

 less crowded. These groups of crowded Unes form rings known as winter rings or 'annuU.' 



Again when the salmon ascends the river to spawn it feeds but scantily if at all, and at 

 spawning time it has lost weight and loses still more after spawning. During this period 

 the scale loses some of its periphery, which gives it an irregular appearance. When the 

 fish resumes feeding in the sea, the more or less ragged scale is mended by scale sub- 

 stance, but a scar is left in the form of an irregular space without fines. This area is 

 known as the 'spawning mark.' 



The growth of the young salmon in the river is shown on the scales in the same maimer, 

 but the lines are finer and more closely set, so that the duration of the river Ufe of a 



