GRAYLING OF GREBE LAKE 



339 



of capture and time of season indicated a reason- 

 ably rapid and constant growth rate for this first 

 year (fig. 24). Lengths of fish in their second 

 summer (from preserved specimens') were taken 

 from grayling captured at night when the fish 

 moved toward the shoreline and could be seined 

 effectively. These collections, started 4 days 

 after the ice cover had disappeared, showed a 

 continuing trend of growth in the fish, until the 

 6th of July (fig. 24). The measurements for age- 

 group I might have tended to reflect only the 

 smaller fish, however, since some larger yearlings 

 had moved to deeper water as evidenced by their 

 appearance in trap nets set during the seining 

 period . 



Calculated Growth Rates Compared 



Growth rates were determined for grayling in 

 the first 3 years by calculating the 1 -year-olds 

 and 2-year-olds separately and treating fish 3 

 years of age and older as a single age-group. 

 Average total fish lengths (inches) to the first 

 three annuli were: I, 4.4; II, 8.9; III, 11.2 (table 

 22). 



In studies of the grayling in North America, 

 length has been measured by different methods. 

 Biologists in Canada (Miller 1946; Rawson 1950) 

 and Alaska (Wojcik 1955) used the fork length 

 measured in millimeters. In the United States, 



Brown (1943) took standard lengths in millimeters 

 and total lengths in inches. Nelson (1954) and 

 the present study have utilized total length 

 measurements in inches. 



To compare rates of growth among different 

 study areas it was necessary to develop relation- 

 ships between the various types of length measure- 

 ments. Fork lengths and total lengths were 

 determined for 17 grayling from Alaska and 33 

 specimens from the United States. All were in 

 alcohol at the University of Michigan Museum 

 of Zoology. In addition, 45 Grebe Lake grayling 

 less than 5.5 inches total length (formalin pre- 

 served) were measured. Conversions between 

 total and fork lengths were read directly from a 



Table 22. — Average calculated lengths in inches of Grebe 

 Lake grayling for their first 3 years of life in 1953 and 1954 

 samples 



Total 



length 



(inches) 



5.0 



4.0 



3.0 



2.0 



1.0 



0.0 



7/2 7/12 7/21 7/30 8/6 8/16 9/l 5/245/30 6/8 6/18 6/26 7/6 7/18 



Sampling date (1954) 



Figure 24. — Seasonal growth rates for grayling of age-groups O, I, during 1954. 



