CLASS PISCES 



461 



The chinook or quinnat salmon, Oncorhynchns tschawytscha 

 (Fig. 391), is the most important commercial fish of the family. 

 It lives in the sea along the Pacific coast " from Monterey Bay, 

 California, and China, north to Bering Straits." It enters the 

 fresh-water streams to spawn, especially the Sacramento, 

 Columbia, and Yukon rivers. The ascent takes place in the 

 spring and summer, beginning in February or March in the 

 Columbia River. The salmon do not feed during this migra- 

 tion, but swim at first slowly and then more rapidly until they 

 reach the small, clear, mountain streams often more than a 

 thousand miles from the sea. Spawning occurs from July to 



Fig. 391. — Quinnat salmon (female). Oncorhynchns tschawytscha. 

 (From Jordan and Evermann.) 



December, according to the temperature of the water, which 

 apparently must be below 54 Fahr. The eggs are deposited 

 upon the gravelly bottoms of the streams, after which both 

 males and females die ; consequently an individual spawns only 

 once during its lifetime. The eggs hatch in about seven weeks, 

 and the young remain on the spawning ground for six weeks. 

 They then float slowly downstream and may be four or five 

 inches long when they reach the sea. The adults are captured 

 by gill-nets and other devices as they ascend the rivers, and are 

 considered the most important of all commercial fishes. The 

 government is artificially propagating the chinook salmon, 

 otherwise its numbers would soon be materially decreased. 



