128 Tliirii/srrnilli Ainnial Mcetimj 



gust'd. ^lany failuiTs of iicsts to develop fry, attributed to lack 

 of fertilization, are really due to causes of the kind here in- 

 dicated. The evils caused hy inipt'rfeet circulation of the water 

 are hy no means ended when tlie egg's are hatched. ^Eany of tlie 

 young fry fall between the stones and are smothered or attacked 

 hy fungus. 



These evils have caused annually the loss of many eg^^ and 

 fry at the Minocqua Hatchery aiul I was, therefore, led to ex- 

 IH'rinu'nt with the artificial nests described. Some fifty nests 

 were nuule hist winter and were put to use this season. They 

 were placed in the ]ionds so as to be sheltered by a stum]) or log 

 and WTre sheltered by a two-sidt'd frame of one-half inch l)oards, 

 placed near the nest. The maU-s liesitated at first to accept 

 tlieni hut soon did so and altogether some seventy-five pair of 

 l)ass used them in ponds where tliere were plenty of old style 1)0X. 

 loose gravel nests. In many cases they preferred the new nests; 

 a good many l)eing used more than once. Many of our breeding 

 l)ass come from lakes where tln'y are accustomed to spawn on 

 l)ars covered liy large stones. Snch fish will liunt for spawning 

 beds like those to wliicli they are accustomed : but if tliey are put 

 into ponds with only sand or fine gravel on the bottom, they will 

 come to the artificial nests and he content with them. They will 

 also hatch out and raise a larger percentage of fry on the artifi- 

 cial nests than on one constnu-tt'd by the fish out of large stones. 

 Imcu though only smaller stones are given them, the circulation 

 of water is better in the artificial nest than under natural condi- 

 tions and the results are C(U"res])ondingly l)etter. Altogether 

 some fifteen nests were hatched successfully under natural con- 

 ditions on thesi' cement nests and the I'esults were sucli as to 

 convince me that it would be well to provide them in all cases. 



The immediate pui'posi' of making the cement nests was, 

 howevei-, not so much to furnish the bass with l)etter nests than 

 he could l)uil(l. but to make i)ossil)le I'xperiments on removing 

 the eggs and hatching them on trays. When the eggs are first 

 laid they adheix' rather firndy to the stones, hut after the third 

 day tliey can easily be detached. Tlu' nest is taken from the 

 ])ond to the hatching house and i)laced on a tuh or similar vessel 

 in the fry trough. The water is allowed to rise in the trough un- 

 til it fills the tul), and, rising through the hole in the center of 



