of the Fishery Board for Scotland. 



63 



These small unspawned fish constitute the bulk of the spring run in 

 the northern rivers, and are comparatively more important to them 

 than to the Tay, where larger fish a year or more older come in during 

 the winter and spring. 



III. Clean Salmon previously marked as Kelts. (Plates IV. and V.) 



The Tay Salmon Fisheries Company are always ready to aid in any 

 enquiry into the life- history of the salmon, and Mr. H. Robb (their 

 secretary), who has made good progress with the study of scales, has 

 kindly sent me from time to time those of marked fish recaptured in 

 their nets during the past few years. Mr. J. B. Taylor and his friends 

 on the Helmsdale have also been good enough to forward me scales of 

 some recaptures on that river. These are all of interest, as the dates 

 of marking in the kelt stage and of recapture in the clean condition are 

 known, and serve as a useful check in the examination of the scales. 



The principal argument against the utility of the scale theory seems 

 to be that no actual proof has so far been adduced that salmon clo not 

 periodically shed their scales and replace them by others. Were this 

 the case, it could hardly be expected that scales renewed from time 

 to time would show the same indications on their surface as those that 

 were of a more permanent nature, and consequently would be of small aid 

 in tracing the previous career of a fish. In the Twenty -third Report I 

 expressed the opinion that there was no periodic shedding of scales, 

 and that any substitution was confined to the repair of damages. This 

 was after noticing that the scales of all the marked fish examined 

 showed lines corresponding to the age of the kelt at the time of marking, 

 followed by the spawning mark or break in continuity of structure 

 caused by injury to the edge of the scale during the spawning season, 

 and around this again the new growth w T as added, the extent of the 

 latter being regulated by the time the fish had remained in salt water 

 before its return to the river and final recapture. The weak point was 

 that the appearance of the scale in the kelt stage could only be arrived 

 at by analogy, and that was hardly convincing. 



This difficulty has now been surmounted, as five of the recaptured 

 clean fish had previously passed through my hands when marked as 

 kelts and I had preserved some of their scales. Thus we are able to 

 compare scales taken from the same fish at two different periods of its 

 life, viz. (1) after spawning for the first time, and (2) after return from 

 the sea preparatory to a second spawning. 



The particulars of marking and recapture of these five fish are 

 given : — 



No. 



Lbs. 



Condition. 



Sex. 



Date. 



Where Caught. 



1180b | 



5 

 14 



Kelt. 

 Clean 





Marked 12th Deceriiber 1904. 

 Recaptured 30th April 1906. 



Helmsdale ( net). 



(rod). 



7780a | 



m 



Kelt. 

 Clean. 



K 



Marked 19th January 1906. 

 Recaptured 25th July 1906. 



Tay (rod). 

 ,, (net). 



9194a j 



ii| 



Kelt. 

 Clean. 



H 



Marked 11th April 1906. 

 Recaptured 9th August 1906. 



(rod), 

 (net). 



9341a J 



3 

 11 



Kelt. 

 Clean. 



M 



Marked 31st January 1906. 

 Recaptured 27th April 1907. 



„ (rod). 

 „ (net). 



9342a 1 



4 

 12 



Kelt. 

 Clean. 



\ F / 

 J 1. 



Marked 31st January 1906. 

 Recaptured 13th April 1907. 



„ (rod). 

 „ (net). 



