Brook trout

Salvelinus fontinalus

• Taxon: Freshwater fish
• Range: Native to the Easter United States
• Status: Not listed under the Endangered Species Act

The brook trout is a fish native to the eastern United States, and is often referred to as speckled trout, spotted trout, brookie, and squaretail. “Brookies” are considered an indicator species, because they help indicate the health or overall quality of the waters they inhabit. Large numbers of brook trout found in a stream indicate a healthy environment while a decline indicates deteriorating habitat and poor water quality.

Appearance

The brook trout has a dark green to brown color with a distinctive light marbled pattern across the sides and back extending at least to the dorsal (back) fin and often to the tail. A distinctive sprinkling of red dots surrounded by blue haloes occurs along the sides of the fish. The belly and lower fins are reddish in color, the latter with white leading edges. Often the belly becomes very red or orange when the fish are spawning, particularly in males.

Habitat

The brook trout inhabits large and small lakes, rivers, streams, creeks, and spring ponds. This small, colorful trout prefers cover such as boulders and logs, where it is protected from strong currents and predators. Brook trout need high quality water and are sensitive to low oxygen, pollution, and changes in pH. Warm summer temperatures and low water flow rates stress brook trout, especially larger fish.

Diet

Brook trout have a diverse diet that includes larval, pupal, and adult forms of aquatic insects. Their diet also includes adult forms of terrestrial insects that fall into the water. Crustaceans, frogs and other amphibians, molluscs, small fish, invertebrates, and even small mammals are included in the menu.

Historical range

Brook trout are native to a wide area of eastern North America, from the Hudson Bay basin and north eastern Canada, much of the Great Lakes basin, a small portion of the upper Mississippi River drainage, Atlantic coastal areas from Maine to New Jersey, and along the Appalachian mountains as far south as Northern Georgia.

Current range

Brook trout are increasingly confined to remote streams in higher elevations due to habitat loss and the introduction of brown and rainbow trout. As early as 1850 the range of the brook trout started to extend west through introductions. The brook trout was eventually introduced into suitable habitats throughout the western United States. The species has also been stocked on every continent except Antarctica. Although not all introductions were successful, a great many established wild, self sustaining populations of brook trout in non-native waters.

Conservation challenges

Brook trout populations depend on cold, clear, well-oxygenated water of high purity. As early as the late 19th century, native brook trout in North America disappeared from many streams as forests were cleared and land was developed. Streams and creeks that were polluted, dammed, or heavy with sediment often became too warm to host native brook trout.

In addition to chemical pollution and algae growth caused by fertilizer runoff, air pollution has been a significant factor in the disappearance of brook trout from their native habitats. In the U.S., acid rain caused by air pollution has resulted in pH levels too low to sustain brook trout in all but the highest headwaters of some Appalachian streams and creeks. Brook trout populations across large parts of eastern Canada have been similarly challenged. Today, in many parts of its historic range, efforts are underway to restore brook trout to waters that once held native populations.

Subject matter experts

• Kelly Taylor, Project Leader at Chattahoochee Forest National Fish Hatchery, kelly_taylor@fws.gov, (706) 838-4626

Federal Register notices

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