Habitat Type: Freshwater
Comments: Rocky runs and pools of small to large rivers; lakes (Page and Burr 1991). Young remain in gravelly streams for 1-5 years (generally 1-2 years, but up to 8 years in some areas), then (as smolts) enter sea (or lake in landlocked populations) and remain there for 1-4 years. Migration habitat between spawning area and ocean optimally should have a minimum of slow- or no-flow areas. At sea, may remain within influence of estuary or move as far as Greenland. Prior to spawning, holds in streams through summer and early fall; optimum conditions include pools of 6 ft or more, water velocity below 1.6 ft/sec, and temperatures of 50-54 F (Clark et al. 1993).
Spawns in streams, usually in gravel-bottomed riffle above or below a pool. In Canada, streams with pH below 4.7 have no existing salmon runs; no impact was observed in streams with pH above 5.4 (Watt 1986, cited by Clark et al. 1993). Eggs are laid in a nest and covered with gravel. Normal egg development requires water temperatures less than 50 F (optimum 43 F). Rearing habitat includes shallow riffle areas interrupted by pools and deeper riffles. Parr require cover such as large rocks. Adults die or return to sea after spawning (males sometimes overwinter in stream). Usually spawns in natal stream.