360 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Although the natural habitat of the trout is confined almost wholly 

 to the colder streams and waters of our country, the acclimatization of 

 these species, and of their proper food, is no longer a matter of experi- 

 ment; and if success in this direction can only be achieved sufficiently 

 to bring this delicate luxury within reach of the people at large, they 

 will need no other argument to convince them that trout-culture is not 

 experimental, but is a work fremi which all may derive direct and sub- 

 stantial benefits. 



But so far as our brook trout (Salvelinus fontinalis) are concerned, 

 until they are more abundant in their native haunts than at present, it 

 will be practically impossible to accomplish results at all appreciable 

 or worthy of notice, except by the method employed here and in other 

 hatcheries. This method proceeds upon the known adaptation of spring 

 water to the artificial development and maintenance of the species. It 

 insures a temperature corresponding with that of the waters of their nat- 

 tural habitat, and, by proper distributive arrangements, this temperature 

 may be kept below 70° F. in the hottest summer weather. The method 

 employed also takes into view the best means and facilities for obtain- 

 ing a sufficient egg supply to meet the purpose in hand ; and, with refer- 

 ence to this, experience has abundantly proven that there is but one 

 reliable course to pursue, and that is to rear the breeders in sufficient 

 numbers to obtain the desired number of eggs. To depend upon secur- 

 ing spawn by angling or seining these fish out of their natural streams 

 would, at present, be almost wholly futile as well as expensive. Those 

 ripe for spawning could not be caught in sufficient numbers by this 

 means to pay the cost of labor expended. But where the fish are kept 

 in ponds or preserves so constructed as to give us absolute control of 

 every period of development from the embryo to the spawner, it is pos- 

 sible to secure very large returns from a comparatively small amount 

 of stock. By this means not a single egg need be lost; every fish can 

 be manipulated without receiving any harm, and the eggs removed and 

 mixed with the proper amount of male secretion to fertilize at least 80 

 to 90 per cent. This is something, however, that art only can do. Na- 

 ture alone would give fertilization to only a very small proportion of 

 eggs spawned^ but art, having the power thus to utilize all there- 

 sources which nature so lavishly furnishes, points out the way to ob- 

 tain the largest results at comparatively little cost and trouble. 



The ponds are fed directly from the lower spring area, which is un- 

 derneath the hatchery, and indirectly by the water of the upper springs, 

 which first makes the circuit of an artificial reservoir, from which it 

 flows through the building, where its passage is utilized in hatching. 

 Thence it enters the raceways at the rear of the hatchery. The amount 

 of stock originally put into these ponds by Mr. Clark consisted of one 

 hundred adult brook trout. This number has multiplied very many 

 times since then. Other varieties of fish have also been introduced at 

 various times, such as the California trout (Salmo iridea), California 



