Environmental Requirements
S. fontinalis prefers clear waters of high purity and a narrow pH range in lakes, rivers, and streams, being sensitive to poor oxygenation, pollution, and changes in pH caused by environmental effects such as acid rain. Its diverse diet includes crustaceans, frogs and other amphibians, insects, molluscs, smaller fish, invertebrates, and even small aquatic mammals such as voles. It provides food for seabirds and suffers attack by lampreys. The brook trout is a short-lived species, rarely surviving beyond four or five years in the wild.
Individuals normally spend their entire lives in fresh water, but some—colloquially called "salters" or "sea-run"—may spend up to three months at sea in the spring, not straying more than a few kilometres from the river mouth. The fish return upstream to spawn in the late summer or autumn. The female constructs a depression in a location in the stream bed, sometimes referred to as a "redd", where groundwater percolates upward through the gravel. One or more males approaches the female, fertilizing the eggs as the female expresses them. The eggs are slightly denser than water. The female then buries the eggs in a small gravel mound; they hatch in 95 to 100 days.
A potamodromous population of brook trout native to Lake Superior, which run into inflowing rivers to spawn, are called "coasters". Coasters tend to be larger than most other populations of brook trout, often reaching 2-3 kg in size. Many coaster populations have been severely damaged by overfishing and habitat alterations, especially by the construction of hydroelectric power dams, on their inflowing streams. In Ontario and Michigan, efforts are underway to restore and recover coaster populations.
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