Brown Trout Description
Brown trout are golden brown in color with large black spots, red spots with pale halos. They are the only trout with both red and black spotting. Young browns have an orange adipose fin.
Brown trout are native to Europe. They were introduced into Idaho waters in 1892. It was not until 1948 that introductions were successful. The brown trout is more tolerant of silt and warm water than native trout and, therefore, has been stocked in areas disturbed by man.
They may be found in rivers, streams, lakes, and reservoirs in the southern part of the state, particularly in the Henry’s Fork River Basin. There are small populations in the Clark Fork River, Lake Pend Oreille, and other waters in the north.
Spawning occurs in October and early November. With her tail, the female digs a shallow depression in which eggs are deposited. After spawning, she covers the eggs with gravel. The eggs hatch the following April. The juvenile brown trout grow quickly for the first three years. As they reach maturity, growth slows. An adult brown might be 4 to 15 years old.
The brown trout is aggressive and territorial, chasing other species away from good cover. It feeds on many different varieties of invertebrates and small fish, both on the bottom and on the surface. Browns forage freely on the surface when mayflies, caddis flies and stone flies are emerging. They will also eat other fish.
Idaho Fish and Game