28 American Fisheries Society. 



can be done in a limited way, because it is being done every 

 year in our state and government hatcheries, but whether in 

 the open waters, under more natural conditions, we can, to 

 paraphrase an old saying, make two fishes grow where one 

 grew before, is quite another matter. To do this would re- 

 quire certain changes in the natural conditions, especially 

 the increase of the food supply and the removal of natural 

 checks on reproduction and growth. 



NATURAL CHECKS 



The natural inimical factors which tend to limit the sup- 

 ply of adult basses in any stream or lake are ; first, conditions 

 interfering with spawning ; second, parasitism and diseases ; 

 third, natural enemies; fourth, amount of food. 



Bass are rather sensitive to environmental conditions at 

 the spawning season, perhaps more so than any other fish. 

 The sudden lowering of the temperature even a few degrees, 

 just at the spawning season may interfere with the process 

 of egg laying and cause the female to become egg-bound so 

 that she may die as a result. Cases of this sort are common. 

 Such temperature changes also cause the male to desert the 

 nest, so that any eggs already deposited are lost, — as every 

 hatchery superintendent knows to his sorrow. 



Preceding such sudden drops in the temperature we 

 often find spring storms occurring and these at times are 

 sufficient to nearly or completely destroy the nests by wash- 

 ing them out or covering them with gravel, mud or other de- 

 bris. I have personally known all the bass nests of a whole 

 stream to be swept out by a succession of such storms during 

 the reproduction season, so that no hatch was observable, 

 even though numerous adults were present and nest mak- 

 ing had been in active progress before the storms. 



In Lake Erie I have observed similar conditions around 

 the Bass Islands where I have studied the reproduction of 

 the small-mouthed bass for the last five years. In 1919, 

 when the weather was especially favorable during the 

 breeding season, there was an astonishing hatch. One 

 could not draw a small minnow seine (we used a fifteen 

 foot common minnow seine in our studies) anywhere about 

 the Islands without taking large numbers of young bass. 

 The season of 1920 showed just the reverse. Heavy storms, 

 with sudden drops in the temperature at inopportune times, 

 apparently destroyed all the nests of the bass about the is- 

 lands, with the exception of a few in well protected localities 

 where the force of the storm could not reach. In 1921 this 

 condition was repeated and no young bass were to be found 



