FOREST, FISH AXD GAME COMMISSIONER. 



161 



exposure to the atmosphere. Similar wells driven upon the station grounds 

 would be apt to have a similar excess of nitrogen. If their flow rose several 

 feet above the ground their water might be successfully deaerated into a 

 proper fish cultural condition. 



It is natural that the salmonoids, containing the most active, nervous, 

 highly-organized species, preferring the cold, well aerated running streams, 

 plenty of room and a predatory existence, should be most susceptible to 

 disease when brought together in large numbers. That the brook trout is 

 more often attacked by disease than an}- others of the family is in part due, 

 of course, to the fact that it is more extensively cultivated. Yet there 

 seems to be no doubt that it is intrinsically more susceptible to general 

 infections than other trouts. It will, for instance, succumb to conditions 

 which do not affect the rainbow, though living side by side with it. The 

 factor of safety in the culture of brook trout is a rather narrow one. At 

 least occasional heavy losses will continue to attend their concentration in 

 large numbers. This is a tax on trout culture which may be paid either 

 in dead trout or in some sacrifice of the magnitude of operations. Reduction 

 of numbers — avoidance of overcrowding — is the most important measure 

 of prevention. 

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