APPENDIX B 433 



salmon's blood is regulated by the water, always being 1 to 3 above its tempera- 

 ture, accounts partly for their habits differing at certain seasons. In cold 

 weather the salmon prefers deep, slow-running pools, and only moves into the 

 more rapid parts where oxygen is in larger quantity as the water gets wanner. 

 As the heat increases and the oxygen decreases, he likes to lie near a fall where 

 more of it is available. 



All these questions have to be considered, but they do not present so many 

 difficulties as they appear to do, and to show that they may be overcome, we 

 may instance the effect of croying a stretch of a river which has yielded good 

 results. By mutual arrangement between the opposite proprietors, who each 

 fish the water three days a week, some 54 has been spent in repairing ancient 

 erections that had become dilapidated, and in putting up new structures in 

 places where it was thought they might do good. Excluding a few grilse and 

 autumn fish, the catch of one proprietor has averaged 35 salmon over the six 

 years since the greater part of the work was done, against about 15 fish for the 

 four years preceding the improvements. The records for the other side are not 

 available, as it forms part of a larger section, and the captures have not been 

 kept separately ; but if we halve the total cost, we find that an expenditure of 

 27 has been followed by an annual average increase of 20 fish on the side 

 referred to. This must be looked upon as well-invested money, even if it be 

 conceded that during the latter years there have been more salmon in the river, 

 and that it has been fished with greater perseverance. Interest on expenditure, 

 depreciation, and cost of ordinary repairs, would be amply covered by 5 or 6 

 a year, which is about the food value of three spring salmon, so whether the 

 croys can be credited with the whole of the increased catch or not, there remains 

 a considerable balance in their favour. Fishing is useless unless there are fish 

 to try for, and if they are in the river, and passing through your part of it, it is 

 worth while doing what you can to induce them to wait long enough to inspect 

 your flies, or, it may be, something which they find more attractive. 



We may now briefly describe the portion of the river on which most of the 

 above-mentioned 54 was spent, and try to convey some idea of what was done, 

 with the aid of a plan. The water naturally divides itself into two pools, the 

 uppermost one (A) being some 300 yards long, and in places 80 yards broad, with 

 a good rocky bottom and deepish water towards the left bank, shelving off to 

 gravel on the other side where the current is weaker. In ordinary states the 

 run of the water was slow and smooth, and it was advisable to break it up a 

 little, so that there might be ripples formed on its surface and diverging currents 

 underneath. This is accomplished by four croys at irregular intervals on the 

 left bank, and by three others on the right bank, which serve to guide the 

 stream back towards the middle of the river, and also during spates to ensure a 

 certain amount of slack water for some distance below. Of these seven croys, 

 four were repaired and three are new. The pool fishes well in high to medium 

 water from January till April, but after the temperature rises it is rather slug- 

 gish for the requirements of salmon. As is often the case, one of the croys 

 seems to be more effectual than the others, judging by the number of fish caught 

 within the area it influences. The lowest croy on the left bank helps to check 

 the pressure of the stream on the ancient and much longer croy immediately 



