THE RACEWAY AS A FISH TRAP. 



By A. Robertson, 

 Harrison Hot Springs, British Columbia. 



In 1914, after the great disaster to the Fraser River sockeye 

 salmon run of 1913, with the approval of Mr. Cunningham, Chief 

 Inspector of Fisheries for British Columbia, I built a chute in 

 Trout Creek with the object of ascertaining the power of salmon 

 to ascend a stream devoid of natural resting places. 



The circumstances of the catastrophe at Hell's Gate are 

 familiar to all interested in the Pacific Coast fisheries, but, for the 

 benefit of others, I would explain that it was caused by the dump- 

 ing of great quantities of railroad building debris into a naturally 

 restricted part of the Fraser River. Some time after the railroad 

 was built, the situation was aggravated by the fall of a rocky cliff, 

 the base of which had become weakened by the cutting of the 

 road-bed. The north bank of the river at this point consists of a 

 vertical and comparatively straight rocky wall, while the south 

 bank where the trouble occurred was irregular. 



The result of the dumping of so much rock was that these 

 irregularities were filled up and a chute was formed in the river. 

 Above and below Hell's Gate minor stoppages were caused in the 

 same way, and these, for the purposes of this paper, are more 

 important than the great blockade at the Gate as they show that 

 very little interference with the course of a stream may result in 

 great injury to the fish, and probably that considerable spawning 

 areas are barred through minor obstructions. 



For the benefit fo the lay reader it should also be explained 

 that the ascent of salmon consists of a succession of diagonal 

 rushes from side to side of the river or past obstructing projections. 

 When the fish find themselves stalled in their ascent they instinc- 

 tively cross the stream; they are incapable of sustained effort and 

 must find resting places at short intervals. 



The chute built in Trout Creek is one hundred feet long, nine 

 feet wide and four feet deep, with an even grade of five per cent, 

 and the velocity of the water, which varies according to height, is 

 about ten feet per second. Many hundred attempts to ascend 



i57 



