WEISEL, HANZEL, and NEWELL: PYGMY WHITEFISH IN MONTANA 



Standard lengths were measured in milli- 

 meters and weights in tenths of grams. To 

 compare our results with the data of other 

 authors who used fork length or total length, 

 it was necessary to use conversion factors. 

 Total length was considered equal to 0.21 plus 

 1.19 standard length, and the standard length 

 equal to -0.09 plus 0.83 total length. The con- 

 version of fork length to total length used was 

 that given by Heard and Hartman (1966) 

 where fork length times 1.0777 equals total 

 length for specimens shorter than 100 mm and 

 times 1.0845 for the larger specimens. 



Scales for age and growth studies were re- 

 moved from an area above the lateral line 

 just posterior to the dorsal fin. Plastic im- 

 pressions were made of the scales and projected 

 to an enlargement of 67 times for measurement. 



SOME MERISTIC CHARACTERS 



Lateral -Line Scales 



A striking character of the pygmy whitefish 

 is its large scales. In its northern range the 

 lateral-line scales number 50 to 73, in Lake 

 Superior 54 to 62, in Flathead Lake 52 to 65, 

 and Bull Lake 54 to 63 (Table 1). The mean 

 number of scales varies somewhat among dif- 

 ferent populations. A low mean of 54.29 is 

 given for fish from Chadburn Lake, Yukon, and 

 a high of 71.57 for low-rakered fish from Lake 

 Aleknagik (McCart, 1970). Pygmy whitefish 



Table 1. — Frequency distribution of the lateral-line scale 

 counts in pygmy whitefish. 



Number 



of 

 scales 



Flathead 

 Lake 



Bull 

 Lake 



52 

 53 



54 

 55 

 56 

 57 

 58 

 59 

 60 

 61 

 62 

 63 

 64 

 65 

 Mean 



3 



4 



3 



5 



12 



14 



14 



15 



9 



6 



4 



6 



1 



3 



58.2 



1 

 2 

 1 

 3 

 6 

 11 

 10 

 4 

 6 

 4 



59.5 



from Flathead Lake and Bull Lake are inter- 

 mediate. The closely related mountain whitefish 

 possesses lateral-line scales ranging from 73 to 

 92 in the Columbia River drainage (Holt, 1960). 



Gill Rakers 



The number and length of gill rakers have 

 proved useful in the systematics of coregonines. 

 The range in gill rakers is considerable in 

 pygmy whitefish, from 12 to 21. On the basis 

 of gill raker number and other meristic and 

 morphological data, McCart (1970) distin- 

 guished two forms of pygmy whitefish which 

 occur sympatrically in some Alaskan lakes. 

 One form has high raker counts and the other 

 has low raker counts. McCart suggested a 

 western refugium south of the ice sheet for the 

 origin of the Alaskan low gill raker form, a 

 Yukon-Bering Sea refugium for the Alaskan 

 high gill raker form, and a Mississippian 

 refugium for the Lake Superior form. 



Pygmy whitefish from Flathead Lake have 

 a range of 14 to 18 gill rakers (mean 15.83); 

 those from Bull Lake range from 15 to 18 

 (mean 16.28). These means are considerably 

 lower than the 18.28 mean of fish from Lake 

 Superior (Table 2). According to McCart's 

 figures, the Flathead Lake and Bull Lake popu- 

 lations would be classified as high-rakered in 

 comparison with Lake Aleknagik populations. 



Table 2. — Frequency distribution of gill raker counts 

 in pygmy whitefish. 



' From Eschmeyer and Bailey (1955). 

 - From McCart (1970). 



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