CUTTHROAT TROUT (UMPQUA RIVER) 



Common Name: CUTTHROAT TROUT 

 Scientific Name: Oncorhynchus clarki 



Listing Date: 08/09/96 



Species Status: Endangered 



Species Trend: Unknown 



Current Estimated Population: Unknown 



SPECIES POPULATION STATUS 



Umpqua River cutthroat trout was proposed for listing on July 8, 1994. 



SPECIES BIOLOGY 



Coastal cutthroat trout differ from all other trout by their profusion of small to medium-size spots 

 of irregular shape. In addition, they do not develop the brilliant colors associated with inland 

 cutthroat trout (a separate subspecies). In the sea-run (anadromous) form of the coastal cutthroat 

 trout, spots and colors are further obscured by the silvery skin deposit common to anadromous 

 salmonids. Non-anadromous (resident) fish tend to be darker, with a "coppery or brassy" sheen. 



The life history of this subspecies is probably the most complex and flexible of any Pacific 

 salmonid. Unlike other anadromous salmonids. sea-run forms of the coastal cutthroat trout do 

 not overwinter in the ocean and only rarely make long extended migrations across large bodies of 

 water. They migrate in the nearshore marine habitat and usually remain within 10 km of land. 

 While most anadromous cutthroat trout enter seawater as 2- or 3- year olds, some may remain in 

 fresh water up to 5 years before entering the sea. Other cutthroat trout may never outmigrate at 

 all. but remain as residents of small headwater tributaries. Still other cutthroat trout may migrate 

 only into rivers and lakes, even when they have access to the ocean. In the Umpqua River, 

 anadromous. resident, and potamodromous (river-migrating) life-histor\ forms have been 

 reported. Details of the coastal cutthroat trout life historv' and ecology, including aspects 

 particular to the various life forms, can be found in published reviews. 



SPECIES DISTRIBUTION 



The Umpqua River cutthroat trout is a "distinct population segment" under the ESA (hereinafter 

 referred to as an Evolutionarily Significant Unit or ESU (56 FR 58612; November 20. 1991 )) of 

 the coastal cutthroat trout ( Oncorhynchus clarki clarki ). The coastal cutthroat trout subspecies is 

 native to western North America and is found in the coastal temperate rainforests from southeast 



