The brook trout (Salvelinus fontinalis) is a small, brilliantly colored freshwater fish native to clear, cold streams and rivers in the headwaters of the Chesapeake Bay watershed. It is also the state fish of New York, Pennsylvania, Virginia and West Virginia.

Brook trout have a dark green back, covered with lighter worm-shaped markings. These markings, resembling the pattern created when the sun shines through rippled water, help to camouflage brook trout from predators such as larger fish and herons, and even anglers. The fish’s bluish sides are sprinkled with yellow spots and red spots surrounded by blue halos. Its fins are starkly edged in white, something that sets it apart from other trout — nonnative brown trout being the most common in the Chesapeake Bay region.

Brookies thrive in clear, silt-free, well-shaded freshwater streams, ideally with numerous pools and a substrate of mixed gravel, cobble and sand. Brook trout are not tolerant of water temperatures above 75 degrees Fahrenheit and are rarely found in developed areas.

Not picky eaters, brook trout feed on a variety of prey — chiefly aquatic insects, like mayflies, caddisflies and stoneflies, but also nonaquatic insects that fall into the water, like ants and beetles. They’ll also eat small crayfish and even consume small finfish like minnows, but only when they are easy to catch.

Brook trout spawn in autumn, mainly in late October and early November. The female uses her tail to create a shallow nest, or “redd,” often near the lower end of a pool where the gravel is swept clean of silt and there’s plenty of fresh, oxygen-rich water. There she deposits eggs, which the male then fertilizes. During spawning, the lower flanks of males become brilliant orange to red.

Once the eggs are fertilized, the female covers them with gravel. The eggs incubate through the winter months, hatching in early spring. Brook trout mature in two to three years and live to about 6 years.

Most grow no larger than 9–10 inches, so a 12-inch brook trout, while not unheard of, is rare and considered a real trophy. Diminutive size notwithstanding, brook trout have always been prized game fish, an especially popular catch for anglers using fly rods.

They are also ecologically significant, if only as the proverbial canary in the coal mine. Because they require pristine, stable habitat with excellent water quality, their presence indicates a healthy stream ecosystem. As water quality in headwater streams declines, so do brook trout populations.

Urbanization affects brook trout through loss of streamside vegetation, loss of stream shading, increased sedimentation, reduced flow and increased high flow events. It also impacts brook trout by changing the physical makeup of streambeds, whether silted over from stormwater runoff or paved over in constructed channels or culverts.

Effects of agriculture on brook trout populations are like those of urbanization: increased water temperature, increased sedimentation, changes in hydrology and loss of streamside vegetation. Additionally, livestock can pollute water and damage stream banks, increasing the erosion of sediment into waterways.

Mining activities impact brook trout populations through acid mine drainage, hydrological changes and physical habitat degradation. Nonnative fish, such as brown and rainbow trout, compete with native brook trout for food and habitat. Brook trout populations can also become fragmented and isolated by physical barriers like dams, which does long-term harm by limiting genetic diversity.

Recognizing the uniqueness of eastern brook trout and their decline in this region, an alliance called the Eastern Brook Trout Joint Venture formed in 2004. This partnership of state and federal agencies, regional and local governments, businesses, conservation organizations, academia, scientific societies and private citizens is working to protect, restore and enhance brook trout populations across their native range.

Whether you are an angler, landowner, business or conservation group, there is a variety of activities you can undertake to support and protect brook trout, including: identifying high-priority brook trout streams; restoring brook trout habitat using bank stabilization, instream structures or streamside plantings; removing dams and other stream blockages; and fencing off livestock to reduce erosion and fecal pollution.

For more ways you can come to the aid of current and future brook trout populations, check out Eastern Brook Trout Joint Venture at http://easternbrooktrout.org.