CHINOOK SALMON (SNAKE RIVER FALL) 







Common Name: CHINOOK SALMON 

 Scientific Name: Oncorhynchus tshawytscha 



Listing Date: 04/22/92 



Species Status: Threatened 



Species Trend: Unknown 



Current Estimated Population: See Species Population Status 



Critical Habitat: Designated 



SPECIES POPULATION STATUS 



Returns of adult fall chinook salmon to the Snake River have declined to very low numbers in 

 recent years. Yearly adult counts at the uppermost Snake River main-stem project affording fish 

 passage averaged 12,720 from 1964 through 1968. 3,416 from 1969 through 1974. and 610 from 

 1975 through 1980. Estimates of wild SnaA:e River fall chinook salmon escapement to Lower 

 Granite Dam have varied as follows: 428 adults in 1983, 295 m 1989. 78 in 1990, 318 in 1991, 

 533 in 1992, 742 in 1993, 405 in 1994, and 350 in 1995. The number of fall chinook salmon 

 redds observed over the remaining 102 miles ( 165 km) of the Snake River available to fall 

 chinook salmon for the period 1987 through 1995 were 66, 57. 58. 37. 41, 47, 60, 53, and 41 

 respectively. However, methods of counting after 1990 differed from those before 1990, so 

 numbers are not entirely comparable. Overall, they show a low, relatively stable number of 

 naturally spawning fish. 



SPECIES BIOLOGY 



The chinook salmon is noted for the black spotting on its back, dorsal fin, and both caudal fin 

 lobes, black pigment along the bases of the teeth and loose conical teeth in mature individuals. 

 Salmon over 14 kg are likely to be chinook. 



The Snake River fall chinook salmon spawns in October and November in the mainstem Snake 

 River from the upper limit of the Lower Granite Dam Reservoir to Hells Canyon Dam (about 165 

 km) and the lower reaches of the Imnaha. Grande Ronde, Clearwater, and Tucannon Rivers or 

 the lower parts of tributaries in October and November. Research in progress has identified some 

 chinook redds below Lower Granite Dam that may be Snake River fall chinook. The juveniles 

 emerge in March and April, beginning their downstream migration within several weeks of 

 emergence. They move seaward slowly as subyearlings. Adults return from the ocean to the 

 Snake River at ages 2-5, with age 4 the most common age at spawning. 



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