7IO BULLETIN OF THE BUREAU OF FISHERIES. 



tablespoonfuls of ordinary com starch have been thoroughly stirred. Here 

 they are allowed to remain ten minutes. The bucket is then filled with clear 

 water and the washing process begins, the water being replaced until only clear 

 water remains with the eggs. They are then stirred continuously with the 

 hands for a period of forty-five minutes, the bucket being at the beginning 

 about one-third full of clear water, to which more is added during this time. 

 At the end of the continuous stirring the worst period of adhesion is over and 

 from that time on the eggs may be stirred and fresh water added every hour 

 until they reach the hatchery. Here they are held in a tub of running water 

 overnight, then screened, measured, and placed in jars on the batteries. 



It will be noted that the two methods of manipulating the eggs are quite 

 at variance. There are so many factors to be considered that it has not yet 

 been decided which procedure is best. 



Pike perch eggs require more care than do the eggs of any other species 

 handled by the Bureau. When received they are usually massed together in lumps 

 and must first be separated with the bare hands and passed through a screen of 

 soft bobbinet before being placed in the jars. While in the jars they require 

 constant attention and must be frequently separated, it often being necessary 

 to take down individual jars several times and pass the contents through the 

 bobbinet screen. 



Although pike perch are found in ripe condition in water ranging from 38° 

 to 60°, more eggs are taken in a temperature ranging from 38° to 50° than 

 above 50°, and the higher temperature seems to be most favorable for hatching 

 the maximum number of fry. Unfortunately, however, the water of the hatch- 

 eries is usually of the colder temperature in which the fish spawn, and a high 

 percentage of fry has therefore been unattainable. An average production in 

 fry of 50 per cent of the eggs taken may be regarded as very good. 



LAKE TROUT. 



The station at Northville, Mich., with its several other lines of fish culture, 

 is also the principal center of the lake trout work, and has a record of over 

 58,000,000 such eggs in one season." As the spawning season is short, however, 

 and is at a period of the year when the fishermen, on account of rough weather, 

 often can not set or take up their nets at will, the collection of eggs must neces- 

 sarily vary in quantity and quality from year to year according to weather 

 conditions. 



The data for one season show the average weight per fish to have been 7.4 

 pounds; that 66 per cent of the catch of females yielded eggs; and that the eggs 

 averaged two-thirds of a fluid quart per fish. 



oSince this writing another spawning season has yielded yi.ooo.cxxj eggs at the Northville station. 



