the Yellowstone Lake population: silver -white, 

 silver-yellow, olive-white, olive-brown, yellow- 

 yellow, and red-pink. A fish classified as silver - 

 yellow would be predominantly silver on the back, 

 blending into yellow on the lower sides and ab- 

 domen. All graduations of the above color were 

 found, so some subjectivity was necessary in 

 determining the proper category for certain fish. 



Comparison of meristic counts 



The samples contained the following age 

 groups and ranges in total length (inches): 



Area 



Yellowstone Lake 

 Creston hatchery 



Bear Creek 

 Sedge Creek 



Mean lengths by age group were not 

 directly comparable among samples because 

 all Yellowstone Lake fish were 15 inches total 

 length +0. 1 inch, and the Creston hatchery fish 

 represented the largest fish of their age groups. 

 Bear Creek and Sedge Creek samples were 

 selected completely at random . 



Counts of spots below the lateral line 

 and hyoid teeth in the above ■samples have been 

 summarized by the method described by Hubbs 

 and Hubbs (1953). This method combines the 

 mean (x), range, standard deviation (s), and 

 standard error (s v of a sample into a single 

 graph (fig. 2). The heavy line indicates the 

 range in number in the particular sample for the 

 character considered. The vertical line indicates 

 the estimated mean number. The solid bar on 

 each side of the mean represents twice the 

 standard error (s ^ \. The clear bars extend- 

 ing from the mean outward on each side represent 

 one standard deviation (s) each. Adequate sample 

 size is indicated whenever one white end bar ap- 

 proaches twice the length of the solid end bar. 

 Sample size appeared to be adequate in all cases . 



14.9 



5.0 

 12 

 14 



6 



8 



4 



5 



7 



The greatest range in number of spots 

 (15-149) was found in the combined sample from 

 Yellowstone Lake; the collection of mature fish 

 from Creston hatchery had the greatest range in 

 number of hyoid teeth (18-68). The smallest 

 ranges in numbers of spots (9-36) and teeth 

 (2-12) were found in the Sedge Creek samples. 

 Bear Creek fish were intermediate both in 

 numbers of spots (24-68) and of hyoid teeth (2-20). 

 The range in counts in samples from some areas 

 failed to overlap, which indicates the large differ- 

 ence among samples in these two characters. 



Sedge Creek fish had the lowest mean 

 Mean number of hyoid teeth (5.3) 



and spots (22.4), followed by 

 Bear Creek (9.2, 43.0) and 

 Yellowstone Lake (13.5, 84.3); 

 Creston hatchery fish had the 

 largest mean number of teeth 

 and spots (39.8, 96.9). Four 

 fish in the samples had no hyoid 

 teeth, including a miature female 

 of age group IV from Arnica 

 Creek measuring 14.8 inches 

 8.7 in total length and 3 immature 



fish of age group II from Sedge 

 Creek measuring 3 . 1 to 3 . 2 

 inches in total length. Dymond 

 (1928) reported that some cutthroat do not have 

 hyoid teeth, but few, if any, workers have pub- 

 lished data to substantiate his statement. 



Data from the Sedge Creek and Creston 

 hatchery samples suggest that the number of 

 spots and hyoid teeth may increase with age 

 (fig. 2). Sedge Creek samples showed increased 

 mean numbers of teeth and spots with increase in 

 age, having 4.0 teeth and 17.3 spots at age II, 

 5.2 teeth and 21.3 spots at age III, and 6.3 teeth 

 and 24.5 spots at age IV. Creston hatchery fish 

 had a similar pattern, with 14.2 teeth and 55.2 

 spots at age I, 33.7 teeth and 95.6 spots at age III, 

 and 42.0 teeth and 98.2 spots at IV. This pattern 

 of increased number of teeth and spots with age 

 was not apparent in fish of age groups IV and V 

 in Yellowstone Lake or in age groups III and IV 

 in Bear Creek. Bear Creek samples had more 

 spots on the average at age III than at age IV. 



Only mature fish were used for compari- 

 son of teeth and spotting counts among populations 



