Oncorhynchus mykiss

By: Mitch Sulkers

Whistler Naturalists

Date: June 23, 2000

 

Rainbows are the most common trout in local waters and are found throughout Whistler’s ponds, lakes, and streams. A good area to view Rainbow Trout is the spawning channel built by the Municipality on the south side of Lost Lake.

 

Colours on the adult’s back range from metallic blue to green or yellow-green to brown. They’re generally silver on the sides and light on the belly. Small black spots cover the head, back, sides, and back (dorsal and adipose) fins. Spots on the tail are in obvious rows. Mature fish tend to have a rosy stripe that extends from the gill covers to the tail fin.

 

Rainbow Trout prefer cool (12 to 18 degrees C), clear, well-oxygenated water, especially where there is abundant cover or deep water. During the spawning season, from May to June in Whistler, adult fish from 11 to 45 centimetres move into shallow riffles in streams, and the females dig nests where eggs are laid and then fertilized by the males.

 

Depending on the temperature, the eggs will hatch in four to seven weeks. The young trout (alevin) then remain another three to seven days in the gravel while they absorb the yolk sac. The young of lake-dwelling fish tend to move into the lake by the end of their first summer, but some may remain in streams for up to three years.

 

Rainbow Trout eat insects, small crustaceans, snails, leeches, and other small fish. Generally, lake fish grow much more quickly than stream fish, although growth is determined by a combination of temperature and habitat productivity.

 

Rainbow Trout usually mature after three to five years. Capable of living to 11 years of age, they spawn repeatedly during their adult life.