29 



out of the e^g mass by frequent changes cf the water in the pan, 

 when the entire mass can be transferred to a larger container 

 for transportation, or directly to hatching trays or jars, if 

 the stripping is done in the immediate vicinity of the hatchery. 



Sudden jars and shocks must be carefully avoided, as the 

 eggs will not withstand abuse of this kind. Where eggs are to 

 be transported any considerable distance, they should be allowed 

 to stand for several hours, with frequent changes of water in 

 the interval, before being transferred to kegs or deep pails for 

 transportation. 



It has been previously shown that water temperatures control 

 the season at which all fishes spawn; it also controls the 

 development of the embryo, and, therefore, the period of incu- 

 bation. Both minnows and suckers hatch over a definite period 

 of time, this period being absolutely controlled by temperatures; 

 in high temperatures (65 to 80 deg. F. ) in 4 to 6 days, in low 

 temperatures (50 to 60 deg. F. ) in 10 to 15 days, and below 50 

 deg. not at all. A sudden sharp drop cf even 10 degrees often 

 proves fatal to both ^gs and newly hatched fry. 



Taking eggs and fertilizing them from the common sucker is 

 simplicity itself; here brute strength is one necessary feature, 

 because the sucker is not only large but one of the most active 

 and powerful fish for its size native to our waters. On the 

 upper Mississippi and its tributaries they literally swarm during 

 May and June over the shallow, rock stream bottoms in swift 

 water, as well as along the rockj', wind-driven shores of many 

 of our northern lakes. Near the close of the spawning season, 

 in deep pools at the foot of rapids on which these fishes spawn, 

 the writer has observed literally bushels of their eggs collected; 

 they having been washed down stream by the strong current and 

 lodged there, for eventual hatching. 



It is no trouble at this season to seine the ripe fish from 

 these spawning beds and take and fertilize their eggs by the 

 millions, if found necessary. Many millions have been so taken 

 by the State Game and Fish Department in recent years, and 

 without any particular care transported, either in ten-gallon 

 cans, or in regular transportation cases, on cloth trays, a 

 distance of 250 miles and hatched over 90^1, in some instances 

 as high as 995t. 



In handling green sucker eggs it is well to bear in mind 

 they must be allowed several hours to harden after being ferti- 

 lized and washed, otherwise the eggs, if placed in jars too soon 

 have a tendency to adhere en masse and then float up as far as 

 the faucet feeding the jar will permit. If this happens the 

 only remedy is to pour the mass of eggs into a screen of proper 

 mesh, floated in a tub of water, and work them through, after 

 which they can be returned to the jar and given no further 

 attention beyond the observation necessary to see the proper 



780060 O - 48 - 5 



