of the Fishery Board for Scotland. 



65 



back at this season, and, along with fish which have never been in the 

 river before, form the valuable runs of winter and spring. The March 

 capture had previously spawned as a young summer fish of the same ago 

 as the Helmsdale salmon, which also returned in spring, though, as there 

 are no nets on that well-managed river to catch them, they did not 

 succumb to the rod till a little later on in the season. 



I have allowed about two years as the usual time spent in the river 

 up to the smolt stage, as this in all the cases seems approximately 

 correct, and it is unnecessary for the present purpose to go into more 

 exact detail. The date of return of the salmon from the sea is estimated 

 from the number of lines put on since the last winter ring, the number 

 of these rings tell us how long it had been in the sea, and the date of 

 marking is known. There is, however, nothing to guide us as to when 

 the kelt left the river, and so this can only be guessed at in most cases. 



For purposes of comparison I add to the diagram examples of typical 

 specimens of the grilse and small spring fish which were marked as 

 smolts. The latter are a year younger than those of the ordinary and 

 larger spring salmon which are returning to the Tay for the first time, 

 and two years younger than the ones that have come up at a junior age 

 and spawned once. 



The diagram does not include examples of nearly all the different 

 classes of kelts that return as clean fish, and I do not propose to 

 base much on it. The similarity of the kelts of autumn fish from 

 the upper water that came back about eighteen months after 

 marking is noteworthy. They were all of good size, marked late 

 in the winter and at some distance from the sea, none of them 

 having previously spawned, as far as I can judge, and they were 

 captured in July and August of the following year. We must 

 remember that the Tay nets come off on 20th August, and after that 

 date there is little chance of marked fish being intercepted, though 

 doubtless many of them enter the river, and hence the percentage of 

 recaptures is rather disappointing. 



All these marked fish show the spawning mark on their scales, and 

 many of them had the distinctive spots and gill maggots which are 

 characteristic of the salmon, to which the local name of bull trout* is 

 given. The only case in which the spawning mark, though apparent, 

 was not very distinct was No. 1395 (Helmsdale), and this fish was 

 judged by its appearance to have been a long time in fresh water. 

 When we find that the spawning mark remains for at least two seasons 

 and is observed on the scales of all the marked fish examined, while 

 there is no sign of it, or of a shortened period of sea -feeding, on the 

 scales of many other salmon, it is not unreasonable to conclude that the 

 latter have not spawned during that time. The first period in the 

 salmon's life after it returns to the river at which it spawns is the grilse 

 stage in its fourth year. Many of the Tay salmon, one and even two 

 years older, have no indication of a previous spawning on their scales, 

 and have perhaps spent three years in the sea. They are younger, but, 

 owing to continuous feeding, may be heavier than some fish of similar 

 appearance returning at the same time on their second visit to the 

 spawning beds. In seasons when both the maiden fish and previous 

 spawners come back freely we have a good supply of salmon. If a poor 

 spawning season, or subsequent causes in the sea interfere with the 

 usual crop of maiden fish, we have to depend largely on the return of 

 the spawners of a year or two before, or vice versa, and in such years 

 fish may be scarce. 



* 'The Bull Trout of the Tay and of Tweed," by W. L. Calderwood. Proceedings 

 Royal Society, Edin., Vol. XXV., Part T. 



