GRAYLING OF GREBE LAKE 



335 



annulus i 



Ficure 21. — Scale from a 1-year-old grayling (total length 5 ins.) captured June 8, 1954. Annulus has just been completed. 



year, were made at intervals throughout the 

 growing season by seining along the shore of the 

 lake after dark. The series was started on May 

 24, 4 days after the ice disappeared from Grebe 

 Lake. Lake temperatures ranged at this time 

 from 44° F. at the 1-foot level to 41° F. at 25 feet. 



Hatchery Creek (the main tributary) reached a 

 maximum of 49° F. during the day and a mini- 

 mum of 34° F. at night. By June 18 when an- 

 nulus formation was 94 percent complete (table 

 21), lake temperatures averaged 1° F. higher 

 than each of those given above. 



Table 21. — Time of annulus formation in Grebe Lake — grayling entering their second summer 



1 Number without scales at time ot annulus formation. 



2 All fish smaller than 3.9 inches were examined. Of these, all specimens from 3.6 inches to 3.9 inches and larger fish randomly chosen had scales developed 

 at time of annulus formation 



