54 



Appendices to Sixteenth Annual Report 



following causes, viz. :— (1), That the volume of water in rivers is con- 

 stantly fluctuating, thus causing at most times a greater or less quantity 

 of water to flow down the passes than they are constructed by their 

 inventors to carry, and thereby throwing them out of working order, as 

 such passes are usually put up promiscuously without proper attention 

 being paid to the regulation of their water supply ; and (2), that they 

 do not carry a suflicient volume of water to attract salmon readily to- 

 ascend them. 



2nd. With the view of studying the efficiency of the pass at CraigOy 

 which is constructed somewhat after the Forsyth system, and of seeing 

 whether there are any special circumstances connected with its local 

 position or construction which make it more likely to be efiective than 

 most passes of this type, I visited it, as already stated, on three 

 occasions. On my first visit the river was at dead low summer level, 

 and the water having been shut off from the fish-ladder by means of a 

 wooden sluice, I was able to examine its construction. On my two 

 subsequent visits the river w^as in moderate flood, but not so high as to 

 prevent my wading along the crest of the dam to the head of the pass. 



I found nothing in the position or the construction of the pass to lead 

 me to think that it was more likely to be effective than other passes 

 constructed on the same system. On the contrary, it seemed to me to- 

 be a bad specimen of its type, and to aflbrd a passage for salmon at even 

 fewer different variations in the water level than is usual with such 

 passes. In the first place, the stops are so low that they do not 

 sufliciently arrest the velocity of the current ; in the second, the open- 

 ings in the stops, particularly in the lower end of the pass, are wider 

 than the intake, consequently when the river is low sufficient water is 

 not retained in each chamber ; in the thii'd, the width of the pass is in 

 no place more than one and a half times greater than the width of the 

 openings in the stops, consequently even in a moderate flood no cushion 

 of qviiet water is secured in each chamber against which the descending 

 current can expend its force before passing on to the next chamber ; 

 on the contrary, great turmoil is caused by the current striking against 

 the stops ; and in the fourth, the widening of the pass at three feet 

 from the intake, and the steep gradient at which it is placed at its 

 upper end, causes the water to descend with so great velocity that, even 

 in a moderate flood, salmon must have great difficulty in ascending the 

 upper fourteen feet — and the higher the river the more would the 

 difficulty increase. 



3rd. Considerable difierence of opinion prevailed among those whom 

 I met at the river-side with regard to the efficiency of the pass. By 

 some it was contended that it is of little or no use ; by others, that 

 salmon ascend it freely at certain heights of the river. The former 

 stated, in support of their opinion, that, under present circumstances, 

 not more than half a dozen fish are taken annually in their waters 

 during the net fishing season ; whereas in 1881, when a breach had been 

 made both at Craigo and Morphie dykes, some 300 fish were taken. 

 The latter based their opinion on observation, stating that they had 

 seen numbers of salmon ascend the pass when the river was at a medium 

 height, but that when it is in flood they ascend the dyke itself on the 

 north side. 



The conclu- Taking into consideration the defects which obtain in Craigo pass — 

 sion arrived at. viz., 1st, as to the position of its mouth; 2nd, as to the width of the 

 intake, and, 3rd, as to the plan on which it is constructed — it seems to 

 me that it can never afford an easy or attractive passage for salmon, 



