1,400 r 



l,200h 



I.OOOh- 



BOOK 



600h 



400h 



2001 



2001 



400f- 



600F 



800^ 



1.000 ^ 



l,200F 



1.400^ 



a bypass trap operated at the Horn Rap- 

 ids irrigation diversion dam (km. 27).^ 

 In the lower Columbia River, large 

 numbers of peamouth ascend tributary- 

 streams for short distances on spawn- 

 ing migrations in early June. The sin- 

 gle specimen collected at km. 32 in 

 June 1957 may have been a stray. 



Northern squawfish (3 ) 



Normal range: Km. to 64 and 1 1 3 to 

 225 (fig. 16, table A. 10). 



Periods of abundance: The catches of 

 northern squawfish were greatest dur- 

 ing May 1958 and smallest in July to 

 October 1957. 



50 100 150 200 250 281 



DISTANCE FROM MOUTH OF RIVER (KM.) 



Figure 14.--CPUE (catch per unit of effort) of chiselmouth 

 from the main stem of the Yakima River in 1957 and 

 1958, by sampling site. 



600 



800 



600 



400 



200 



3 



200 



400 



600 



800 



400 



200 



u 



200 



400 



50 

 DISTANCE 



100 

 FROM 



281 



600 



50 100 150 200 250 281 



DISTANCE FROM MOUTH OF RIVER (KM) 



Figure 15.— CPUE (catch per unit of effort) of carp from 

 the main stem of the Yakima River in 1957 and 1958, 

 by sampling site. 



Peamouth (29) 



The Yakima River is apparently not nor- 

 mally used by the peamouth. In June 

 1954, three peamouth were collected in 



150 200 250 



MOUTH OF RIVER (KM) 



Figure 16. — CPUE (catch per unit of effort) of northern 

 squawfish from the main stem of the Yakima River in 

 1957 and 1958, by sampling site. 



Longnose dace (15) 



Normal range: Km. 8 to 64 and 120 to 

 281 (fig. 17, table A- 11). 



Periods of abundance: Longnose dace 

 were more abundant from May to 

 October than at other times of the year. 



Comments: The numbers of longnose 

 dace sharply decreased from Novem- 

 ber to March. The more logical causes 

 for this decrease are mortality, migra- 

 tion, or unavailability to the sampling 

 gear. No reasons exist for suspecting 

 a mass mortality or movement; the 

 populations are probably essentially 

 stable. We suggest that the preferred 

 habitat of the longnose dace changes 

 from a swift riffle in the summer and 



■^ Richard T. Pressey, Biologist, Wash. Dep. Fish., 

 Olympla, Wash. Unpublished data. 



12 



