432 THE SALMON RIVERS OF SCOTLAND 



to fish in high water. It is curious to note the varied ways in which anglers 

 make use of croys. One well-known actor, in trying to reach rising trout, stood 

 on the top of the erection, quite ignoring the fact that every fish within range 

 saw him distinctly and fled ; while another fisherman with more experience and 

 not so much accustomed to appear before an admiring audience, utilised the 

 shelter to conceal himself. Croys may be convenient for casting from, but this 

 is only a subsidiary reason for erecting them. 



If the proprietor of a Scotch salmon fishery owns both banks of the stream, he 

 is in a position to make what erections he likes, provided these do not cause 

 damage to the lands of his neighbours either above or below, and do not impede 

 the free ascent of salmon. In cases where only one side is possessed, he must do 

 nothing to interfere with the natural course of the river without the opposite 

 proprietor's consent. In the latter case it is more satisfactory to have a mutual 

 arrangement, so that work may proceed on both sides, as this generally proves 

 much better than improving one bank only. It does not appear necessary to 

 ask consent to repair an old croy, even if this means almost rebuilding, but 

 there must be some evidence, in the shape of foundations or otherwise, to show 

 that it previously existed, and the former dimensions must be adhered to as 

 nearly as possible. 



Any difficulty as to legal rights having been overcome, it now remains to 

 decide where operations are to be commenced, and what the purpose in view is. 

 Great caution must be observed in doing anything to a part of the river that is 

 already good, in case the change may be detrimental instead of beneficial, and 

 work done here should be of a tentative nature, unless it is very clear what the 

 effect will be. Equal care is necessary in changing the course of the stream im- 

 mediately above a favourite pool, lest gravel be carried down and accumulate in 

 the latter. Until experience is gained it is better to make a beginning with a 

 stretch that is of little use, but which seems capable of improvement, and plans 

 must be made to suit the size of water in which it is likely to fish best. If you 

 can get a pool to fish well in both low and high water, it shows the system has 

 been good, but results must not be expected too soon, as it often takes a long 

 time before they are evident. 



It is impossible to indicate with any exactness what should be done to improve 

 a stretch of river that has not been thoroughly examined in all states of the 

 water, and for this reason no general rules can be laid down. A water-gauge is 

 a great aid to observations, and one can usefully note the level of the river when 

 each fish is killed. Plans of procedure much depend on whether you are dealing 

 with a large river with a fairly regular flow, or with a smaller one which rises 

 and falls quickly, and after rain resembles a mountain torrent. In it, croys 

 must be of slight elevation and properly sloped, otherwise they will not with- 

 stand the force of the water. Also you have to consider the class of salmon you 

 wish to encourage, and the season of the year when they arrive in your water. 

 The salmon requires a certain amount of oxygen to be present in the water he 

 lives in. Too much does not suit his taste, and makes him dull and sluggish, 

 and too little will not sustain his life. The oxygen which he can abstract from 

 the water varies in amount inversely with its temperature, being much greater 

 at 35 than at .60 F. This, along with the fact that the heat (and volume) of a 



