Bear and Sedge Greeks drain limited areas 

 to the east of Yellowstone Lake and empty into 

 Turbid Lake which lies about 2 miles from Yel- 

 lowstone Lake. Summer stream flow in both 

 streams is less than 5 cubic feet per second. 

 The original populations .of trout in both streams 

 were probably once connected with the Yellow- 

 stone Lake population. Thermal activity of long 

 duration-' in and around Turbid Lake has long 

 since isolated these two populations. 



penetration of the preserving fluid. Measure- 

 ments of total lengths were made from preserved 

 specimens. Sex was determined by visual in- 

 spection of the gonads, using a microscope when 

 necessary. As the differences between sexes in 

 numbers of hyoid teeth and spots were not statis- 

 tically significant, the sexes were combined in 

 the Sedge Creek and Bear Creek samples for 

 statistical comparisons with the other popula- 

 tions. 



Bear creek was stocked in 1939 and 1940 

 with 50,000 cutthroat trout from Yellowstone 

 Lake- but no other contamination of the origin- 

 al strain has occurred. This stream had an 

 endemic population of cutthroat before 1939, as 

 Kendall (1915) reported a native population 

 there in 1914. 



Cutthroat are abundant in Sedge Creek; 

 this population is apparently uncontaminated, 

 as a thorough search of all existing records re- 

 vealed that no stocking of exotic strains of trout 

 has occurred.— Apparently the population has 

 been isolated from Yellowstone Lake for many 

 decades even though it is separated from the 

 lake by only a few miles. Thus, the present 

 study compares cutthroat from Yellowstone Lake 

 with cutthroat stocks that have been separated 

 from Yellowstone Lake for 13 years (Creston 

 hatchery, four generations), for 21 years (Bear 

 Creek) , and for a long but unKnown period of 

 time (Sedge Creek) . 



Methods 



Spawning females from Yellowstone Lake 

 tributaries were taken from traps maintained at 

 the mouth of these streams. Fish of both sexes 

 were obtained from Sedge and Bear Creeks by 

 applying a small amount of emulsified rotenone 

 to the streams a short distance above their en- 

 trance into Turbid Lake . The number of 

 specimens collected was controlled as the chem- 

 ical immediately entered the highly toxic lake. 

 Specimens from the Creston hatchery were 

 selected at random from mature females and 

 from yearling fish of both sexes. 



The fish were preserved by immersing 

 alive in a 10-percent solution of formalin after 

 making a small slit in the abdomen to allow 



All hyoid teeth, regardless of size, 

 were counted. Fused teeth with separate points 

 were counted as two separate teeth. Special 

 caution is needed in examining hyoid teeth 

 (Miller, 1950; DeWitt, 1954) as they are fre- 

 quently imbedded in the mucus covering the 

 tongue and can be broken off easily. Accurate 

 counts are difficult without damaging the speci- 

 men. In this study, the floor of the mouth was 

 removed; sections were labeled and dried slightly 

 with radiant heat to fully expose the teeth. 

 Counts were made with a binocular microscope 

 using a blue light. The teeth stood out in good 

 relief, and the surface of the tongue could be ex- 

 amined thoroughly for evidence of missing teeth. 



The spotting count was similar to the 

 counts made by Quadri (1959) in defining differ- 

 ences between Salmo c. lewisi and Salmo c. 

 clarki. All spots below the lateral line on the 

 left side of the body were counted with the ex- 

 ception of spots smaller than a single scale 

 (speckling). Parr marks were not counted, and 

 fused spots were counted as one. Spots falling 

 on the lateral line were included if more than 

 half of the area of the spot was below the line. 

 Spots on the head, tail, and lower fins were not 

 enumerated. Ages of all fish were determined 

 by scale examination with the exception of the 

 known -age hatchery fish. 



Data on coloration were collected in 

 1959 from live spawners of both sexes entering 

 traps on 6 tributaries of Yellowstone Lake: Arnica, 

 Pelican, Clear, Cub, Grouse, and Chipmunk 

 Greeks . The predominant colors on the body 

 above and below the lateral line were recorded 

 for 10 percent of the fish on each run. The 

 following major color types were observed in 



2/ Personal correspondence from Oscar T. Dick, acting Chief Park Ranger, 

 Yellowstone National Park,"Wyo., dated February 14, 1961. 



