400 



200 



200 



400 



50 100 150 200 250 281 



DISTANCE FROM MOUTH OF RIVER (KM.) 



Figure 12.~CPUE (catch per unit of effort) of mountain 

 whitefish from the main stem of the Yakima River in 

 1957 and 1958, by sampling site. 



those caught were mature, this move- 

 ment was probably a spawning migra- 

 tion. We suspect that the whitefish that 

 spawned in the upper river were resi- 

 dents of the Yakima River and that the 

 population below km. 72 migrated into 

 the Yakima from the Columbia River. 

 The mountain whitefish receded from 

 the upper Yakima by January and from 

 the lower river before May. Collections 

 of yearling whitefish were rare, which 

 is perplexing when the abundance of 

 the adults is considered. 



Cutthroat trout (28) 



Three were collected at km. 169 in No- 

 vember (fig. 13, table A-4). 



Rainbow trout (18) 



Normal range: Km. 201 to 281 (fig. 13, 

 table A- 5). 



Period of abundance: November to May. 



Comments: Rainbow trout are repre- 

 sented by resident and anadromous 

 types, Steelhead trout, the anadromous 

 type, move out of the Yakima in the 

 spring. Rainbow trout juveniles taken 

 below km. 177 from March to June 

 probably were steelhead trout smolts. 



Brown trout (25 ) 



Brown trout, which have been introduced 

 to provide sport fishing, were taken at 

 km. 24 in January, knn. 217 in March, 

 and 40, l6l, and 169 in May (fig. 13, 

 table A. 6). 



Brook trout (23) 



Small numbers of brook trout were taken 

 above km. 177 on all but the third 

 (September- October) trip (fig. 13, 

 table A- 7). The brook trout is com- 

 mon in irrigation canals in the Ellens- 

 burg area but not in the main stem of 



50 100 150 200 250 281 



DISTANCE FROM MOUTH OF RIVER (KM) 



Figure 13.— CPUE (catch per unit of effort) of cutthroat, 

 rainbow, brown and brook trout from the main stem of 

 the Yakima River in 1957 and 1958, by sampling site. 



the Yakima River. The brook trout 

 usually were taken near a slough or 

 irrigation water outlet. 



Dolly Varden (29) 



The single Dolly Varden trout that was 

 collected at km. 266 in April 1957 

 probably originated in a reservoir 

 above the study area. 



Chiselmouth (1) 



Normal range: Km. to 169 (fig. 14, 

 table A- 8). 



Period of abundance: Chiselmouth were 

 most abundant January to May and least 

 abundant July to October. 



Comments: The fact that larger num- 

 bers of adult chiselmouth were taken 

 in March and May than in other months 

 made us suspect that these adults had 

 moved into the Yakima from the Co- 

 lumbia River on a spawning migra- 

 tion. 



Carp (9) 



Normal range: Km. to 137 (fig. 15, 

 table A- 9). 



Comments: Most carp were taken in the 

 lower half of the study area. It was 

 the only abundant species that did not 

 notably avoid the area between km. 72 

 and 105. Small carp, less than 200 mm. 

 long, were rare. Carp were not taken 

 above km. 169, but a few were ob- 

 served during other studies in an irri- 

 gation canal that enters the Yakima 

 River near km. 217. 



11 



