194 REPORT OF THE COMMISSIONERS OF 



conditions to be considered. After a pond is stocked with fish, and well stocked, 

 water, food and temperature, all being suitable, what rules can be enforced to insure 

 that the pond will be fished with moderation in season and not at all out of season ? 

 But that is a matter for the law makers, game protectors and the consciences of the 

 anglers, rather than for the fish breeder; therefore, let us ccinsider a little further the 

 question of temperature of water suitable for trout. Waters that already contain trout 

 that do well in them can be planted, as the fact that trout thrive in them \=, prima facie 

 evidence that the waters are suitable for the fish. In extending the range of trout, or 

 in planting streams that have been fished out, and in which the conditions may have 

 changed, it is safe to plant in waters that never exceed a summer temperature of 

 seventy degrees Fahrenheit. Rainbow and brown trout will thrive in waters of higher 

 temperature than are suitable for brook trout, and brook trout will live in well aerated 

 water above seventy degrees; at the same time water of seventy and five-tenths 

 degrees has killed both brook and brown trout, probabh' because it lacked vigor, 

 which comes from force and aeration. Trout grow little, if any, when in water below 

 forty degrees, and to be at their best they must have, during a portion of the year, 

 water that ranges from si.xty-two degrees to se\'enty degrees, as this temperature 

 hatches the insect life, v/hich constitutes a large part of the food of trout. While food 

 is all important, trout must have room, also, in which to grow. It is self evident that 

 if trout are planted in numbers to exhaust the food supply, they will not thrive ; but 

 aside from that trout must have space to be at their best, for it has been demonstrated 

 that a given number of trout in a certain number of cubic feet of water will do better 

 than the same number of trout in half the quantity of water, both lots of trout being 

 fed the same amount of food. 



How far trout may be acclimated to water of higher temperature than that to which 

 they are ordinarily accustomed, has not yet been fully demonstrated. In South Africa 

 the brown trout has been hatched in water as high as seventy-nine degrees, and in this 

 country the rainbow has been found to thrive in swift, well aerated streams that reach 

 eighty-five degrees Fahrenheit. The experiments of Dr. Davy [Physiological 

 Researches) to determine the temperature fatal to trout are of interest, and aside from 

 the question of temperature, as they show how trout try to escape when the water 

 becomes too warm. He placed a common European trout {fario) or brown trout of 

 this State, of about a quarter of a pound weight, into a good volume of water at sixty- 

 two degrees, which was prett)' rapidly raised to seventy-five degrees by additions of 

 warm water, when it became very active and tried to leap out. In an hour the water 

 was increased to eighty degrees, and after a few minutes more to eighty-five degrees, 

 when it became convulsed, and, although transferred to cool w'ater, died. When the 

 water had sunk to seventy degrees a smaller trout and a minnow were put in, and 



