THE HISTORY OF FISH CULTURE. 551 



houses where white fish are to be hatched shoukl be constructed upon 

 some lake or poud that freezes over early and does not thaw out until 

 April 1. 



" It is stated as a reason why spring- water is better for hatching fish 

 eggs than lake water, that it is generally more free from sediment, some 

 kinds of which are highly detrimental to the successful hatching of the 

 fish ova. Whereas our inland lakes freeze over early in the fall, and 

 are not free from ice until late in the spring. This ice is perfect protec- 

 tion against any agitation of the water, and gives an opportunity for 

 any sediment that may be in it to settle to the bottom, where it mnst 

 remain until spring, and until the eggs are hatched and dist;il)uted. 

 Consequently the water in all of oui* inland lakes is, during winter, as 

 clear as crystal. 



" You also wish me to give my views in reference to using Detroit 

 River water. To this I will frankly say th%t I should much prefer it to 

 any spring water in this or any other State for hatching white fish. 

 But there are some objections which arise in my mind even to this 

 water. I am aware that this species of fish are natives of our great 

 lakes and rivers, and consequently it would be supposed that this water 

 must agree with them, and that success would be certain if this water 

 was used. But has it not occurred to all ijersons who have given this 

 subject much thought that much the largest proportion of these fish run 

 to the shoals of those lakes during spawning season to deposit their ova"? 

 These shoals are the first to freeze over in the fall and the last to thaw 

 in the spring. This keeps at nearly the same temperature during 

 incubation. Although it may be said that during their migration from 

 Lake Erie to Lake Saint Clair some deposit their spawn in the rivers ; 

 it is not very probable that much of it is hatched. 



" I am aware that many hatch in and about the ponds where the fish- 

 ermen preserve their fish for winter use. This tends to prove that the 

 shoals are the place where they hatch most largely, as the ice remains in 

 these ponds much longer in the spring than in the strong current in 

 Detroit River. 



" If water is used from this river it must change in temperature many 

 times during the winter, as it is well known that the ice leaves the river 

 quite often during the four-and-a-half months of the period of incuba. 

 tion. No one can gainsay the fact that in the hatching of fish ova, if 

 the water is of a perfectly even temperature, it will be attended with 

 more favorable results than when frequently changing, from any 

 cause, even if such change is not more than two or three degrees. Is it 

 not also a fact that the ice frequently leaves the lower part of Lake Saint 

 Clair early in March ? If so, would not the westerly winds roll the 

 water in the upper part of the river ? This sediment would be depos- 

 ited on the eggs, and in consequence of its fine, clammy nature, would 

 be injurious to them. I noticed this was the case in a little experimental 

 arrangement of A. M. Campau, some two years since, where this water 



