1912 AND FISHERIES COMMISSION. 271 



stant number of young trout. Further, practically enough large adult 

 trout are present to eat at least 90 per cent, of the trout fry before these 

 young reach the breeding stage, and to furnish a number of offspring 

 practically just sufficient to furnish food for themselves and similar 

 large fish. Thus a surplus of not more than a pair or two comes to 

 maturity out of the hundreds of annual progeny of each pair of breed- 

 ing fish, to replace the old trout which pass on through accident or 

 senile decay. 



" When, however, man appears, and a considerable number of the 

 breeding fish are removed by him, the most important consequence is a 

 sudden diminution in the number of eggs laid and a corresponding dimi- 

 nution in the number of fry hatched; consequently, a relatively larger 

 proportion of young fish, which are destined to go as food for the ' big 

 fellows.' A two-pound trout, for example, requires a certain weight of 

 animal food per day. He will persistently hunt until this amount is 

 secured and his voracious appetite is satisfied. If, then, only a relatively 

 small number of small troiut are present, it is possible that every one of 

 these may thus fall victims; and not alone an actually smaller number, 

 but even no surplus fry, may remain to grow to become breeding adults. 

 When this occurs the trout fishery in that brook declines, and the waters 

 soon become occupied by less valuable fish, or else the stream remains 

 uni)roductive, yielding either nothing to man, or, at least, less than its 

 normal productive capacity. * * * The necessity of meeting these con- 

 ditions has led to biological studies which prove the following facts of 

 economic importance : 



" 1. More trout fry can be secured by artificial impregnation of the 

 egg than are ordinarily hatched under natural conditions. 



"2. The trout fry can be reared artificially in immense numbers, 

 with less mortality, than in nature. 



" 3. By an increased quantity of food the rapidity of growth may be 

 accelerated, and by subsititution of an artificial food in place of young 

 fish a greater weight of trout may be secured at less expense." 



In the United States, not only the Federal Government, but almost 

 all the individual states, are increasing the yearly production of fish by 

 means of enlarged or additional hatcheries. An idea of what is being 

 done in this direction may be gained from the following figures, taken 

 from the thirteenth annual report of the Forest, Fish and Game Com- 

 mission of the State of New York : 



Summary op Fish Distribution for the Year ending December 31st, 1907. 

 IN THE State of New York. 



Brook Trout I.SIS.MO Frostflsh 3.100.500 



Brown Trout 1.051.750 Maskalonge 5,000.000 



Lake Trout 8,758.900 Pike Perch 36.855.000 



Rainbow Trout 822.100 Shad 566 100 



Small Mouth Black Bass 11,000 Smelt 100,000.000 



Tomcod 65.600.000 



Whiteflsh 15.510.300 



Total Game Fish 1 2,459.700 Total other fish 226,631 ,900 



