75 



THE POPULAR SCIENCE MONTHLY. 



Stripping a Small Trout. 



pounds weight prefers something more substantial, like a yearling 

 trout or two for breakfast and a few more at intervals, with flies 

 and worms for dessert ; and this cannibalism is what keeps the 



balance of life in a natural 

 state. If, however, it is de- 

 cided to follow the first- 

 named system, it will only be 

 necessary to provide spawn- 

 ing races for the adults and 

 ^ &**?' ^\l x)l ' follow the rules for hatch- 



|^4 ^k V*jj ing the eggs, and either turn 



A A V out the product as fry or 



;*^^ ^ "Iwv as yearlings; the latter will 



give the best results where 

 transportation is not needed, 

 as in the work of the fish 

 commissions of the different 

 States. 

 Where it is desired to make a business of trout-raising a series 

 of small ponds are necessary. After leaving the springs the water, 

 in summer, is continually approaching the temperature of the air ; 

 and when it gets to 70 the danger line is reached. In swift water 

 our brook trout have lived at five degrees above that point, but 

 they suffered, and some have died, while others lived until the de- 

 clining sun permitted the water to cool a trifle. This is a point 

 that should be in mind when planning ponds, for it is of the 

 greatest importance. A spring brook that will sustain many 

 trout in a pond of half an acre might fail to keep a single one if 

 the area was doubled. The surface and the shallows are warmer 

 in summer than the deeper portions, and in the case of springs in 

 the bottom of lakes or ponds the trout will gather about them in 

 warm weather. In the pond system the ponds are so small that 

 the fish can be seen at all times and their growth noted, so that 

 those which have outstripped their fellows may be taken out and 

 placed with others of the same size. This is practiced once a year 

 with the larger fish and about three times during summer with 

 the " babies," or those not yet arrived at the dignity of yearlings. 

 Cannibalism is not only prevented by this, but the smaller ones 

 will have a chance to get food at the first table, from which they 

 have been debarred. 



Perhaps a description of the ponds that I have made for the 

 Fishery Commission of the State of New York at Cold Spring 

 Harbor, Long Island, may best illustrate the idea of small ponds, 

 first explaining that the object of the ponds is not only to grow 

 trout, but to get the greatest amount of eggs for hatching in order 

 to stock public waters with the different species of trout, such as 



