Brook Trout

Salvelinus fontinalis

Brook trout. Photo from RMBL Archives

Brook trout, Salvelinus fontinalis, belong to the family Salmonidae, which includes salmon, trout, char, whitefish, and cisco. Coloration ranges from yellow, to blue, to greens and browns with vermiculations of lighter shades across the flanks and back. In a typical North American headwater stream, adult brook trout range from 5-11 in. (13-27 cm) in length and weigh from 1-5 pounds (0.5-2.5 kg).

Brook trout live in the higher latitudes of the northern hemisphere in cool, clear, highly-oxygenated streams, ponds and lakes. In the absence of brown trout and cutthroat trout, brook trout may be the largest and most dominant species of fish in cold water stream ecosystems.

Physiologically, these fish have evolved to thrive in very cold fresh water. Their diets include just about any living organism that they can physically consume and their fine teeth and strong jaw make them effective diurnal hunters. They feed primarily on invertebrates drifting in the water column, but larger fish also consume vertebrates such as salamanders.

Ecological Relationships
Brook trout are territorial of their habitat and feeding stations, surrendering only to larger brook trout or bigger fish of other species. In the Rocky Mountain region brook trout may share their environment with brown trout, lake trout, rainbow trout, and cutthroat trout. Their main predators include humans, bald eagles, and other larger fish. Brook trout are visual predators that need light in order to locate their prey. Both adults and juveniles feed constantly throughout the day but are most active in the early morning and late afternoons.

Status and Conservation
Although the current population status of brook trout is stable, the long term survival of this species is threatened by two major sources: acid rain and global climate change.

Encyclopedia of Life
Learn more about Salvelinus fontinalis at the Encyclopedia of Life.

Literature Cited
Karas, N. (1997) Brook Trout. The Lyons Press, New York, New York, USA.

Peterson, D. P. Fausch, K. D. White, G. C (2004) Populations Ecology of an Invasion: Effects of Brook Trout on Native Cutthroat Trout. Ecological Applications (14) 754-772.

Many thanks to Sarah Foster and Dr. Pat Magee at Western State College for this submission, and to RMBL Researcher Dr. Bobbi Peckarsky for her review and additions. Photo credit to Angus McIntosh.