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numbers of both small and large whitefish were consistently high 

 throughout the sample section. Whitefish were notably scarce in 

 the irrigation ditches and Swamp and Steel creeks. Burbot (Lota 

 lota ) were scarce througout the Study Area, and never received a 

 rating higher than "few." Burbot over 6 inches were encountered 

 much more often than individuals under 6 inches, but the larger 

 fish were found consistently only in sample sections B, C and I. 

 Suckers were found in high numbers throughout the Study Area, 

 with the exception of sample section A, where they were absent. 

 Sucker fry were particularly abundant, with the number of 

 individuals per sub-section often exceeding 100. No attempt was 

 made to separate the abundance of longnose suckers ( Catostomus 

 platyrhynchus ) from white suckers ( Catostomus commersoni ) , 

 although longnose suckers were generally in far greater 

 abundance. Longnose dace ( Rhinichthys cataractae ) were found in 

 high numbers throughout the Study Area, except in sample section 

 A, which has the highest gradient and largest substrate of any 

 sample section. Mottled sculpin (C ottus bairdi ) were most 

 plentiful in the upper sample sections (A,B and C) and Steel 

 Creek, and almost absent from irrigation ditches. 



Growth of Arctic grayling 



Between July 7 and September 1, the mean total length (+ SD) 

 of YOY Arctic grayling increased from 2.45 + 0.12 inches to 4.26 

 +0.37 inches (Table 4, Figure 3). These fish are considerably 

 longer than those measured by Liknes (1981) for the same time of 

 year. He sampled 44 age 0+ grayling in Sandhollow Creek and the 

 North Fork of the Big Hole from July 11-15, 1979 and found a mean 

 total length (+ SD) of 2.17 + 0.22. During the same general time 

 period in 1988 (July 12- 14) , 24 age 0+ grayling from the Big 

 Hole River immediately upstream from the Wisdom Bridge had a mean 

 total length (± SD) of 2.68 + 0.19 inches. This size difference 

 could be due to temperature differences between these two 

 tributaries and the mainstem of the Big Hole River, although this 

 cannot be substantiated because tributary water temperatures were 

 not measured. Spawning periods during the two years were 

 similar, and probably cannot contribute to an explanation of the 

 size difference. Liknes reported that most spawning in the Big 

 Hole River in 1979 occurred from late April to early May. 

 Shepard (1989) believed spawning occurred from the end of April 

 through the first week in May in 1988, based on observations of 

 the first ripe fish on April 20 and the first spent fish on May 

 4. 



The length-frequency distribution of Arctic grayling over 6 

 inches had two peaks, apparently corresponding to age 1+ and 11+ 

 fish (Figure 4) . Fish assigned to age 1+ were mainly between 

 7.0-8.5 inches, age 11+ fish were mainly between 9.0-11.0 inches, 

 and the two fish over 11.0 inches may have been age III+ fish 



