188 THE SALMON RIVERS OF SCOTLAND 



The time of ascent of fish at Kilmorack is fixed by the thermal 

 conditions. As in many other places in Scotland, such as the 

 Garry falls, Kildonan, Orchy, Dochart Falls, etc., fish do not ascend 

 owing to the combination of the otherwise passable obstruction and 

 the low-water temperature. Scottish fish will not jump at a fall 

 when the water is in a wintry state, as Norwegian fish will do, but 

 if the obstruction is removed they will continue to ascend. In 

 heavy and broken water such as occur in the gorge above Kil- 

 morack they will not ascend rapidly, and if floods of snow water 

 come down upon them they will be checked in their ascent, and may 

 even be impelled to drop back till such floods are over. In those 

 early months of the year the river temperature is constantly lower 

 than the temperature of the sea from whence the fish come ; these 

 fish leave a cold sea for a colder river. Not till April does the 

 river temperature become equalised with the sea temperature. 

 Those conditions have been well worked out, and comparisons made 

 between many rivers. x We require more information as to how far 

 clean spring fish which ascend fresh water drop back to the sea and 

 reascend at a later period. That the habit is fairly common has 

 been believed for many years by observant netsmen, but very little 

 reliable information exists. The best recapture of a marked clean 

 fish showing a descent and reascent comes from the river we are 

 now considering. 



When fish were being netted in order to secure ova for the 

 hatchery, on 9th December, 1907, a clean fish of 22 Ib. was also 

 captured. It was marked with label No. 405 4B. The place of 

 capture was the Castle Pool below the Cruives. This fish on 19th 

 March, i.e. in ninety days, was recaptured on the rod in the river 

 Ness at Dochfour, six miles up. It was then a fish of only 20 Ib. 



Two other clean Beauly fish were recaptured, one in 52 days, the 

 other in 115 days, but neither had left the river in the interval ; the 

 recaptures were both made in the Beauly. The case of the fish 

 migrating, when clean, from the Beauly to the Ness is, so far as 

 recaptures go, quite unique, although some four fish in the kelt 

 state have been recorded as having changed their rivers. The rivers 

 Beauly and Ness have, of course, a common estuary, and the distance 

 from the mouth of the one to the mouth of the other is only about 

 ten miles. Whether or not clean fish which ascend many miles up 

 a river do commonly return as this fish did, remains, I hope, to be 



1 19th, 20th, and 21st Annual Reports, Fishery Board for Scotland, Part ii. 

 Journal Scottish Meteorological Society, 3rd series, No. vi., p. 336. 



