GRAYLING OF GREBE LAKE 



Table 15. — Number and place of fish marking in 1953, and 1954 recaptures 



327 



Type of mark and place of release (1953) 



Adipose fin removed .. 



Outlet downstream 



Right pectoral fin removed. 



Outlet upstream... _. 



Left pectoral fin removed. .. 



Lake 



Streamer tags. 



Trout 



Gravling. 



Trout 



Grayling- 

 Trout 



Grayling.. 



Trout 



Hatchery Creek I Grayling. 



Species 



Number 

 marked 



and 

 released 



183 

 263 

 374 

 392 

 295 

 1,032 

 7 

 295 



Locations and numbers of recoveries (1954) 



Outlet 



Up- 

 stream 



Down- 

 stream 



Creek 2 



Hatchery 

 Creek 



1 

 3 

 4 

 44 

 3 

 117 



North- 

 west 

 Creek 



South 

 Creek 



Total 



7 

 34 



33 

 101 



12 

 145 



EGG PRODUCTION, DEVELOPMENT, AND 

 HATCHING 



Perhaps the most fundamental of all factors 

 controlling populations is the annual recruitment 

 to the breeding stock. The greatest mortality is 

 suffered before, during, and immediately after 

 hatching. To obtain an insight into the amount 

 of mortality in the Grebe Lake system during 

 these early stages of fish life it was necessary to 

 develop experimental procedures for estimating 

 egg production and fry returns to Grebe Lake. 



Fecundity of Grebe Lake Grayling and Trout 



A knowledge of potential egg production in 

 spawning was prerequisite to later estimates of 

 fry yield. Eggs were taken from 37 spawning 

 grayling and counted. These 37 fish were in 

 three total-length groups; (1) less than 11 inches, 

 (2) between 11 and 12 inches, and (3) 12 inches 

 and longer. The average number of eggs of 

 females, respectively, in the foregoing length 

 groups were: 1,889, 2,344, and 2,781 (table 16). 



These values are not greatly unlike those found 

 by other investigators. Brown (19386) stated 

 that grayling trapped at Grebe Lake in 1935 

 averaged 1,650 eggs per female. One 12-ounce 

 specimen (approximately 14.5 inches total length) 

 contained 5,563 eggs. Brown (19386) also found 

 3 females in Georgetown Lake which averaged 

 32 ounces and contained 12,946, 12,642, and 

 8,135 eggs, respectively. Rawson (1950) reported 

 most of the females used for spawn-taking at 

 Reindeer Lake, Alberta, Canada, in 1948 and 1949 

 produced from 4,000 to 7,000 eggs apiece with a 

 few of the largest containing more than 10,000 

 eggs per female. 



In order to estimate potential and total egg 

 production, females of the grayling spawning in 

 streams were grouped in the same length intervals 

 as above. The potential egg production for the 

 different inlets and the outlet were computed for 

 the 2 years (tables 17 and 18). The results 

 showed an approximate total egg potential of 

 8,640,000 in 1953 and 10,600,000 in 1954. 



Table 16. — Number of eggs per female (based on 37 speci- 

 mens of the Grebe Lake grayling 1953, 1954) by total 

 length groupings 



1 Parentheses contain number of fish in each group. 



Table 17. — Potential grayling egg production on various 

 Grebe Lake waterways in 1953 



Note.— Total expected number 8,638,368; maximum, 9,871,496; minimum, 

 7,405,221. 



485001 0-59-4 



