|
Oncorhynchus mykiss (on-co-wren´-cuss me´-kiss)
GENERAL
INFORMATION
Rainbow
trout, and all other species of trout, char, grayling and
whitefish are members of the salmon family, Salmonidae Trouts.
Rainbow trout and steelhead (an anadromous or sea-run form
of rainbow trout) are native to the Pacific Northwest and some of the streams
west of the Rocky Mountains. The original distribution of rainbow and steelhead
trout extended from northern Mexico to southeastern Alaska and inland wherever
rivers and streams connected with minimal natural obstructions to the Pacific
Ocean. Rainbow trout have been widely introduced in many parts of the United
States as a popular sport fish species. Natural obstructions such as dams have
restricted the distribution of the steelhead form. The rainbow trout you will
see on the SalmonCam were bred at the Goldendale Hatchery from stock that originated
in California.
Rainbow
trout spawn in late winter and early spring. The female
opens and closes a gravel nest called a “redd” before
and after each release of eggs and sperm. The eggs and
newly hatched fry receive no parental care. The newly hatched
fry remain in the stream gravel for several days and continue
to feed on a small yolk sac before venturing out into flowing
waters.
DESCRIPTION
Rainbow trout (freshwater form), 6–24". COLOR: olive above; sides
have wide red stripe, black spotting; yellowish to white below. Mouth white;
no teeth on back of tongue. 8-12 anal fin rays; adipose fin present, usually
with black edge.
Steelhead
(sea-run form), to 3'9" (1.1 m); 42 1/8 lbs
(19.1 kg), Elongated; head large; straight lateral line; silvery blue above
with black spotting;
sides silvery; pink wash on fore half of sides. 1 triangular dorsal fin,
small adipose fin, and crescent-shaped tail fin with black
spotting. Mouth large;
jaws extend to below eyes. Steelhead return up coastal rivers to spawn.
FOOD
Young rainbow trout feed primarily on aquatic (water) insects, such as caddis
flies, mayflies, and midges that are floating or swimming in the water or the
water surface. As they grow larger their diet includes small fish however,
they continue to consume large amounts of larval and adult insects. Seasonally
the diet may change as water conditions and other seasonal factors influence
prey populations. Steelhead eat crustaceans, and squid, herring and other fish
while in the ocean.
In turn,
young rainbow trout often are eaten by a variety of piscivorous
(fish-eating) fishes, such as sculpins, northern pikeminow,
smallmouth bass, and larger trout
and salmon. When in shallow water, they also are fed upon by kingfishers,
herons,
eagles, osprey, gulls and terns, otters, and raccoons. Humans are the most
frequent predators of larger rainbow trout and steelhead.
HABITAT
Rainbow trout typically live in fast-running clean streams and deep lakes with
high levels of dissolved oxygen. Steelhead inhabit inshore ocean at mid-depths
and near the surface; spawns in freshwater streams and rivers.
|
