and the Naknek system may be related to the use 

 of only trawls in Lake kSuperior and several gears 

 in the Naknek system. In the present study few 

 round whitefish were captured in trawls. McCart 

 (1963), using gill nets, found little or no associ- 

 ation between pygmy whitefish and mountain 

 whitefish Prosopium williamsoni (Girard) or lake 

 whitefish Coregonus clupeaformis (Mitchill) in 

 Cluculz and Tacheeda lakes, British Columbia. 



AGE AND GROWTH 

 BODY-SCALE RELATION 



The relation between body length and the an- 

 terior scale radius (mm. multiplied by 80) was de- 

 termined for 456 pygmy whitefish from Brooks 

 Lake and 500 from South Bay. Data from both 

 lakes indicate this relation is highly sigmoid. 

 Rounsefell and Everhart (1953, p. 324) suggest 

 that problems of curvilinearity can be solved by 

 omitting the earliest years and back calculating 

 only those ages that do not deviate appreciably 

 from linearity. The persistence of a curvilinear 

 body-scale relation in the older age groups of 

 Naknek system pygmy whitefish prevented any 

 linear treatment of older fish. Also, these fish are 

 relatively short lived, reaching a maximum age of 

 3 years in Brooks Lake and 5 years in South Bay. 

 Age was determined from scale annuli, which, ex- 

 cluding scales from a few older fish, were not 

 difficult to locate. 



Fourth degree polynomial equations were found, 

 excluding highly spurious intercepts, to fit fairly 

 closely the empirical data for the body-scale re- 

 lations of Brooks Lake and South Bay pygmy 

 whitefish. These equations were calculated from 

 individual pairs of body-scale observations. Mean 

 body lengths for each scale radius are plotted 

 against the calculated relations for both areas 

 (figs. 4 and 5). Body length at scale formation 

 is apparently between 22 and 27 mm. as determined 

 by: (1) staining small fish for the first evidence 

 of scale development and (2) calculating the inter- 

 cept for collections of age 0+ fish after scale de- 

 velopment. Separate equations were necessary for 

 the Brooks Lake and South Bay collections be- 

 cause of strikingly different growth rates in the 



20 40 60 



ANTERIOR SCALE RADIUS (MM.X80) 



80 



Figure 4. — Body length-scale radius relation of pygmy 

 whitefish in Brooks Lake. Solid line is calculated equa- 

 tion ; points represent mean body lengths for given scale 

 radii ; dashed line connects estimated intercept of 25 

 mm. with the logical portion of calculated curve. 



160 



140 



120 



100 



20 - 



/ 't.= 442.62-25.l7622S+0.596IIS 2 -0.00574S 3 -+0.00002S 4 



20 40 60 80 100 



ANTERIOR SCALE RADIUS (MM.X80) 



120 



Figure 5. — Body length-scale radius relation of pygmy 

 whitefish in South Bay. Solid line is calculated equa- 

 tion ; points represent mean body lengths for given scale 

 radii ; dashed line connects estimated intercept of 25 

 mm. with the logical portion of calculated curve. 



564 



U.S. FISH AND WILDLIFE SERVICE 



