of the Fishery Board for Scotland. 



97 



migrations which may occur at this stage. The Stormontfield smolt 

 to grilse records, as well as records which have quite recently been 

 obtained in Devonshire by His Grace the Duke of Bedford — both of 

 which depend for identification on the cutting of the adipose fin — 

 support the records given above. A copy of the Tweed records 

 will be found in my previous paper on marking (20th Annual Report 

 Fishery Board for Scotland, Part II., pp. 57 and 58). The other data 

 in the diagram are all of Tay fish. First we have the grilse kelts — 

 numbered in blue : — 



9402 



' 4 lbs. : 25": kelt grilse : F. : 5th Feb. 1903: Logierait, Upper 



Tay. 



10| lbs - : 30 " : clean salmon: F. : 31st July 1903: Flookie 



8329 



6 lb.: 24": kelt: M. : 10th Feb. 1903: East Haugh, Tummel. 

 8343 ^ 14| lbs. : 33|" : clean: M. : 20th Aug. 1903: Pyeroad netting 



station. 



These two show the short migration. 



f 6| lbs.: 29": kelt grilse: F. : 9th Jan. 1902: West Shot, 

 8044 \ Stanley. 

 ( 19 lbs. : 36f" : clean salmon : 14th Mar. 1903 : Upper Bluehill. 

 This fish shows the long migration, returning as a clean spring fish. 

 In the next group (numbered in red) we have kelts of 8 lbs., 10 lbs., 

 and 11 lbs. ; we will take the 11 lb. fish first, since it shows again the 

 short migration. 



R171 J 11 lbs. : 38" : kelt : F. : 18th Jan. 1902 : Battleby. 



' \ 17 lbs. : clean : F. : 20th Aug. 1902 : Dove Cot Station, Estuary. 



The two others show long migration. 



10 lbs. : 33" : kelt : F. : 7th Mar. 1902 : Tummel. 

 19 lbs. : clean : 16th Feb. 1903 : West Shot, Stanley. 

 8 lbs. : 32" : kelt : F. : 11th Feb. 1901 : Cloichfoldich, Grand- 

 5852 \ tully. 

 19 lbs.: 37|". clean: F. : 5th Mar. 1902: Pyeroad, Estuary. 

 This last is taken from my previous Report, p. 7 1 . 



Those three kelts seem to indicate from their weights, as compared 

 with the weights of unspawned fish, that they are the kelts belonging 

 to the same class as the small salmon represented in the diagram by 

 Nos. 8343 and 9402. They are therefore placed as five-year-olds, it 

 being noticed in passing that 8044 at time of recapture and other clean 

 fish of similar habit are of the same year although not spawned in the 

 previous winter. 



Up to this point the age of the fish may, it seems to me, be estimated 

 with a fair amount of accuracy. When we regard the next kelt 

 recaptures, however, we are confronted with the evidence that the 

 weight of a clean fish of five years old may be the same as that of a six 

 year old fish, or, in other words, the heavy spring fish of the Tay are not 

 all the same age, and it may be that the majority are six years old 

 rather than five years old. It is noticeable also that we have not 

 evidence of an increase in weight in the middle group comparable with 

 the increase of the grilse kelt 8044, and it may be, though the lack of 

 evidence to the contrary is by no means conclusive, that this middle 

 group represents a period in the life of the adult salmon when, as it 



