86 



the bottom, and yet the salmon did not seem to be in- 

 jured by it. We have kept young California salmon in 

 a preserve when the water rose above 80 degrees in tem- 

 perature, and although the inlet was open and they could 

 have gone out, as many of them did, others remained 

 until we thought it better to drive them out by drawing 

 ott' the water. However this temperature is not safe 

 for them unless there is a large body ot water or consid- 

 erable motion to it which gives it life and enables the 

 fish to live in it longer. In an aquarium in which there 

 were pairs of Kennebec and California salmon, brook- 

 trout, salmon-trout and grayling, when the water rose to 

 74 degrees they were greatly distressed, coming to the 

 surface and gasping. When it reached 75 degrees they 

 all died. 



It must not be forgotten that in ponds there is often a 

 spring to which the fish can have recourse and which 

 will save their lives. It is not always possible to judge 

 by the temperature of the surface, for that below may be 

 lower, but it is better to be on the safe side as far as pos- 

 sible. The larger the fish the more they will suffer and 

 the sooner they will die. They exhaust the oxygen 

 much more rapidly than the fry. 



Brook trout are only suitable for clear, cold water, of 

 which the temperature never goes above 70. Salmon 

 trout will live only in clear, cold, deep lakes. They need 

 the purest water of any fish in this country. In the 

 aquarium above referred to were put brook trout, salmon 

 trout, greyling, California and Kennebec salmon and Cali- 

 fornia brook trout, and as the water became warm the 

 salmon trout began to suffer first, and died before the 

 mercury went up to 74. The brook trout went next, 

 the greyling next, the California brook trout fouith, the 

 Kennebec salmon fifth, and the California salmon last. 



