SOCKEYE SALMON (SNAKE RIVER) 







Common Name: 

 Scientific Name: 



SOCKEYE SALMON 

 Oncorhynchus nerka 



Listing Date: 11/20/91 

 Species Status: Endangered 

 Species Trend: Unknown 

 Current Estimated Population: 

 Critical Habitat: Designated 



<10 ADULTS/YEAR 



SPECIES POPULATION STATUS 



Adult returns to Redtlsh Lake were 1, 0. 4. 1, 8. 1. 0. and 1 in 1989, 1990, 1991. 1992, 1993, 

 1994. 1995, and 1996 respectively. NMFS has determined that a second population, residual 

 sockeye salmon, resides in Redfish Lake and is part of the Snake River sockeye salmon 

 population listed as endangered. This residual population shares the same spatial and temporal 

 spawning distribution, and is genetically very closely linked to the anadromous sockeye gene 

 pool. 



SPECIES BIOLOGY 



The sockeye salmon (anadromous) and kokanee (non-anadromous) are distinguished from other 

 Pacific salmon by the 28 to 40 long, slender, closely-spaced gill rakers on the first arch, by the 

 few pyloric caeca, and the fine black speckling on the back. Taxonomically, the kokanee and 

 sockeye salmon do not differ. Mature kokanee are generally smaller than sockeye salmon; the 

 usual "length is 20 to 23 cm, although individuals as large as 53 cm have been reported for some 

 productive lakes. A typical 4-year-old Columbia River sockeye is 51 cm long and weighs 1.7 kg. 

 Fork length of most sockeye salmon measured at Redfish Lake Creek Weir ranged from 48 to 

 64 cm. 



Adult sockeye arrive at Redfish Lake, Idaho in July and August, and they spawn on the beach 

 areas during October and November, and then die. Fecundity in sockeye depends upon the size of 

 the female, ranging from about 1 .500 to 4,500 eggs per female. Sockeye fry emerge from the 

 gravel in early sprmg (April and May). Most sockeye in Redfish Lake remain in the lake for one 

 or two years, migrate out to sea, and reside in the ocean for two to three years before returning to 

 spawn. 



64 



