The number of salmonid taxa within some genera (e.g. Salmo, Salvelinus, and Coregonus) listed in various taxonomic databases (e.g. Fishbase or Eschmeyer's Catalog of Fishes) has increased very rapidly over the past 15-20 years. Many of these taxa are not widely accepted across the international community and are associated with very sparse data, leading to significant difficulty in accurately carrying out Red List assessments. The SSG strongly recommends a rigorous evaluation of the validity of these species designations, which can have real implications where legal protection is reflected by the use of these binomial taxonomic names.

Listed as Least Concern in view of the large extent of occurrence, large number of subpopulations, large population size, and lack of major threats. Trend over the past 10 years or three generations is uncertain but likely relatively stable, or the species may be declining but not fast enough to qualify for any of the threatened categories under Criterion A (reduction in population size).

This species is native to most of eastern Canada and the north-eastern United States, from Newfoundland to the south-western side of Hudson Bay, and south in the Atlantic, Great Lakes, and Mississippi River basins to Minnesota, north-eastern Iowa, Wisconsin, Lake Michigan (but not Illinois streams), Chagrin River (Lake Erie drainage) in north-eastern Ohio, northern New Jersey, New England, and southward in the Atlantic and Mississippi basins of the Appalachian Mountains to northern Georgia (Smith 1979, Trautman 1981, Becker 1983, Cooper 1983, Smith 1985, Etnier and Starnes 1993, Jenkins and Burkhead 1994, Menhinick 2001, Behnke 2002, Hartel et al. 2002, Moyle 2002, Bailey et al. 2004). Sea-run populations at least formerly extended from the Atlantic provinces of Canada to Long Island, New York (Scott and Crossman 1973), including Hudson Bay (Behnke 2002). Brook Trout has been introduced in most of the lower peninsula of Michigan, western North America, and temperate regions in many other parts of the world.

This species is represented by a large number of subpopulations and locations.

Total adult population size is unknown but relatively large.

In the eastern United States, intact stream populations of brook trout (where wild brook trout occupy 90-100% of their historical habitat) exist in only 5% of subwatersheds; wild stream populations of brook trout have vanished or are greatly reduced in nearly half of subwatersheds; the vast majority of historically occupied large rivers no longer support self-reproducing populations of brook trout; brook trout survive almost exclusively as fragmented populations relegated to the extreme headwaters of streams; even with no further habitat loss or increase in exotic fishes, existing habitat fragmentation could lead to continuing extirpations at the subwatershed scale (Hudy et al. 2005, Trout Unlimited 2006).

This species has been replaced by introduced non-native brown trout and rainbow trout in many part of the native range (Behnke 2002).

Sea-run populations apparently were common in coastal portions of their range prior to the 1700s (Ryther 1997). Sea-run populations that historically were found in one or two tributaries to Massachusetts Bay have been extirpated (Hartel et al. 2002). Reduced populations of anadromous brook trout still occur in a few tributaries to Nantucket Sound, Buzzards Bay, and Narragansett Bay (Hartel et al. 2002).

Trend over the past 10 years or three generations is uncertain but likely relatively stable or slowly declining.

Most populations occur in clear, cool, well-oxygenated creeks, small to medium rivers, and lakes. Individuals may move from streams into lakes or the sea to avoid high temperatures in summer. Some populations migrate between freshwater and saltwater habitats. Other populations (known as "coasters") live in lakes and migrate to streams to spawn, or they remain in the lake to spawn. Preferred water temperature is around 14-16 °C; brook trout do poorly where water temperature exceeds 20 °C for extended periods (see Sublette et al. 1990). Spawning occurs in cool water (usually less than 15 °C) usually over gravel beds in shallow headwaters but also may occur in gravelly shallows of lakes if spring (groundwater) upwelling and moderate current or nearby surficial inflow (Quinn 1995) are present. Eggs are buried in nests in gravel. In Ontario, eggs were buried at 7-20 cm in bottom substrate (Snucins et al. 1992).

Poor land management associated with agriculture and urbanization ranks as the most widely distributed negative impact on stream populations of brook trout across the range in the eastern United States (Hudy et al. 2005, Trout Unlimited 2006). Non-native fishes rank as the largest biological threat to lake populations (Hudy et al. 2005, Trout Unlimited 2006).

Range has contracted in southern Appalachian region due to impacts of logging, fires, river impoundment, road and railroad construction, land clearance for agriculture and human habitation, and encroachment of introduced rainbow trout and brown trout (Larson and Moore 1985, Galbreath et al. 2001). Introduction of hatchery-reared brook trout from the northeastern United States has also affected native populations, but genetic sampling of populations in the Pigeon River system in North Carolina indicates that a high proportion of sampled populations consist of unaltered native fish (Galbreath et al. 2001).

Sea-run populations in eastern Canada and the northeastern United States were decimated over the past 200 years by overharvest, habitat degradation, and stocking of hatchery-reared brook trout and other non-native salmonids (Ryther 1997).

Historically, most of Lake Superior's 3,000 miles of shoreline and tributary streams supported coaster brook trout populations. In the mid-1800s, unregulated fishing decimated these stocks, and in-stream habitat loss due to wide-scale logging further reduced numbers and prevented stocks from recovering (USFWS, Region 3). Exploitation of coaster stocks and demands on their habitat accelerated in the twentieth century. The opening of the Lake Superior watershed by road, rail, and water removed protection by isolation. Fishing pressure increased, and habitat damage from hydroelectric dams, road and railway construction, and mining probably also contributed to the decline. In some areas, sea lamprey (Petromyzon marinus) predation, which peaked in the late 1950s (Curtis 1990), and the introduction of Pacific salmon and rainbow trout (Onchoryhychus mykiss) and brown trout (Salmo trutta) were additional stressors that probably reduced coaster abundance and distribution (Newman and DuBois 1996). By the mid-1900s only a handful of tiny remnant stocks still existed (USFWS, Region 3).

In general, brook trout populations respond most negatively to factors that decrease survival of large juveniles and small adults and that decrease growth rates of small juveniles (Marschall and Crowder 1996).

Currently, on a range-wide basis, this species is of relatively low conservation concern and does not require significant additional protection or major management, monitoring, or research action. However, it is of high conservation concern in certain regions.