34 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



SO transparent as that of Craig Brook, aud the bottom can hardly be 

 seen at the depth of 4 feet. This circumstance is regarded as favor- 

 able. The inclosure is located on the lower stretches of the brook, not 

 more than half a mile from its mouth, with low banks on either hand 

 and a very gentle current flowing over a bed that is for the most part 

 gravelly but in part consists of a peaty mnd that supports a luxurious 

 growth of aquatic vegetation. The general depth is less than 4 feet, 

 but two of the pools are 8 feet deep and another is 6 feet deep. The 

 width of the stream is from 20 to 80 feet. The inclosure occupies the 

 entire stream for a distance of 2,200 feet, embracing an area of about 

 2^ acres. At either end is a substantial barrier, consisting of wooden 

 racks, which obstruct the current very slightly but confine the salmon 

 securely. The lower barrier is provided with a gate, which swings open 

 to admit boats, aud at the upper barrier are located the spawning-house 

 and watchman's camp and a small storehouse. 



The temperature of the water during the summer months generally 

 ranges between 60° and 70° F., but the surface temperature occasionally 

 rises to 76°, 80°, and even 84°. During sultry weather the temperature 

 at the bottom has been observed and in the deeper pools has been found 

 to be notably lower than at the surface. Thus a temperature of 75° 

 at the surface has been found to be accompanied by 08° at the bottom; 

 78° by 74°; and 81° by 72°. It is probable that to the existence of these 

 deeper pools the survival of the salmon through extremely hot weather 

 may be ascribed. 



After their liberation in the inclosure the salmon are at first quite 

 active, swimming about and often leaping into the air. This continues 

 for several weeks. After that they become very quiet, lying in the 

 deepest pools and rarely showing themselves until the approach of the 

 spawning season. 



Most of the deaths occur during the first few weeks of their impris- 

 onment, doubtless in consequence of injuries received in capture or 

 during transfer, though high temperature in the inclosure itself about 

 the time of the introduction of the salmon may be one of the causes of 

 mortality. Fish that escape the dangers of June appear to become 

 acclimated and able to endure the high temperatures of July and 

 August without injury. 



Notwithstanding salmon enter tbe rivers in spring or early summer, 

 ascending at once to their upper waters and there, in fresh water, 

 awaiting the spawning season, fresh water is not essential to the activ- 

 ity of their reproductive functions. At the Canadian fish-breeding 

 station of Tadoussac, where salmon are almost the only fish cultivated, 

 it has for many years been the practice to hold their brood fish in an 

 inclosure supplied with salt water, which tlows and ebbs through tlie 

 barrier confining the salmon, and the development of eggs and milt is 

 in no wise unfavorably affected, 



