REPORT OF COMMISSIONER OF FISH AND FISHERIES. LXXIII 



A few white-fish fry were kept in a floating box in one of the fry 

 tanks, and in the same tank outside the floating box about 1,000 pike- 

 percli fry were retained. Both of these lots throve on food found in 

 the water. The superintendent's attention was called by Mr. E. M. 

 Ball to the fact that the white-fish fry avoided the Diaptonuis, which is 

 easily distinguished by its long antennae. He then began a series of 

 observations with both white fish and pike-perch fry, and found that 

 Mr. Ball's conclusions were correct. The fry partook freely of the other 

 forms of life, but refused to touch the Diaptomus. It was also observed 

 that by the end of the third or fourth day all forms of life became 

 scarce except this. 



As the success of the white-fish work depends to a large extent upon 

 the abundance of natural food when the fry are first planted, and as 

 this food seems to be present only when the water is clear, it seems 

 advisable, in making future plants, to pay more attention to the condi- 

 tion of the water in which de])osits are made. In other words, if the 

 water in one locality is clear the fry should be planted there, even 

 though it may not be the natural spawning-ground of the fish. 



Further experiments were conducted at the station this season to 

 determine how long eggs may be held in water before applying the 

 milt and still retain their vitality. As a result of these observations, 

 it was ascertained that 97 per cent could be fertilized after being in 

 the water six minutes, 98i per cent being fertilized where the milt was 

 api)lied instantly. At the end of the eighth minute only 81 per cent 

 were impregnated; at the expiration of the tenth minute, 47i per cent; 

 at the fifteenth minute, 40i per cent; at the twenty-fifth minute, 17 per 

 cent. After sixty minutes not an egg was fertilized. The object in 

 making these experiments was to find out how long the eggs may be 

 held in water and still be capable of perfect fertilization, in order to 

 determine how wide a range may be depended on in remilting. 



Experiments with pike perch eggs during the past season seem to 

 indicate that the eggs of this fish may be reunited to great advantage; 

 but unfortunately the experiments could not be continued this year. 



A number of experiments were also tried to determine whether or 

 not it is advisable to remilt all eggs. From the first lot 16i per cent of 

 unimpregnated eggs were found where the milt was applied only once 

 and 12.2 per cent where applied twice. In the second lot fQrtilization 

 was the same by both methods. In the third lot there was a diflerence 

 of less than 0.4 i^er cent. 



As it is impossible to use the dry method of fertilization in very rough 

 weather or when raining very hard, some experiments were tried to 

 determine the difference in results between the wet and dry methods. 

 In the first two experiments the wet process produced slightly better 

 results; in the last, the dry. 



The season for pike perch was peculiar in many respects. It opened 

 ten days late, as the ice remained in the lake much longer than usual; 

 but fishing ceased about the usual time, and the rapid rise in tempera- 



