General Impact
Introductions of invasive Salvelinus fontinalis as the result of angling and aquaculture have facilitated a severe impact on native systems throughout the world. Impacts include the severely threatening replacement and displacement of, as well as, competition and hybridization with native fishes; predation and population reduction of amphibians to the point of endangerment; and top down cascading trophic interactions resulting in modifications of benthic zooplankton, macroinvertebrates, and algal communities. Brook trout have been found to compete with, displace, or replace many fish species throughout the world including golden trout (Oncorhynchus aguabonita), brown trout (Salmo trutta), Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri), Colorado River Basin cutthroat trout (Oncorhynchus clarki pleuriticus), westslope cutthroat trout (Oncorhynchus clarki lewisii), greenback cutthroat trout (Oncorhynchus clarki stomias), and Lohantan cutthroat trout (Oncorhynchus clarki henshawi), bull trout (see Salvelinus confluentus in IUCN Red List of Threatened Species), and chinook trout (Oncorhynchus tshawytsch).
Hybridization between brook trout and native species poses another threat to endemic fish. Hybridizations with brown trout (Salmo trutta), Dolly Varden (Salvelinus malma), and threatened bull trout (Salvelinus confluentus) have been recorded. Finally, many introductions of Salvelinus fontinalis were to previously fishless lakes which resulted in a dramatic reduction of many threatened, even endangered amphibian populations. Specific negative interactions by introduced brook trout have been imposed on the Chiricahua leopard frog (see Rana chiricahuensis in IUCN Red List of Threatened Species), boreal chorus frog (Pseudacris maculata), Colombia spotted frog (Rana luteiventris), wood frog (Rana sylvatica), tailed frog (Ascaphus truel), cascade frog (see Rana cascadae in IUCN Red List of Threatened Species), Pacific tree frog (Pseudacris regilla), Iberian frog (see Rana iberica in IUCN Red List of Threatened Species), tiger salamander (Ambystoma tigrinum), northwestern salamander (Ambystoma gracile), long-toed salamander (Ambystoma macrodactylum), boreal toad (see Bufo boreas in IUCN Red List of Threatened Species), palmate newt (Triturus helveticus), alpine newt (Triturus alpestris), marbled newt (Triturus marmoratus), and endangered species mountain yellow-legged frog (see Rana muscosa in IUCN Red List of Threatened Species) (Bosch et al. 2006; Bradford, 1998; Dunham, 2004; FishBase, 2001; Leary et al. 1993; Levin et al. 2002; Nakano et al. 1998; Reiman et al. 2006; Spens et al. 2007; Fuller, 2006; Jansson, 2008).
Location Specific Impacts:France 
Ecosystem change: Introductions of salmonids including Salvelinus fontinalis have resulted in a significant reduction of amphibians in the lakes of Hautes-Pyrenees, France (Delacoste, 1997). Iran, Islamic Republic of
Competition: Salvelinus fontinalis is known to compete with native fish for resources in the Tigris-Euphrates basin (FishBase, 2001). New Zealand
Competition: Significant dietary overlap between non-native Salvelinus fontinalis with native brown trout (Salmo trutta) indicates a strong likelihood of competition within sympatric populations (Fechney, 1988). Poland
Competition: Salvelinus fontinalis has imposed negative ecological interactions with endemic species in Poland (FishBase, 2001).
Hybridisation: Salvelinus fontinalis hybridises with native brown trout (Salmo trutta) (Jansson, 2008). Spain
Reduction in native biodiversity: Predation on native newts Triturus helveticus, Triturus alpestris and Triturus marmoratus by introduced salmonids including Salvelinus fontinalis has resulted in a significant reduction of the distribution of these amphibians in northern Spain (Orizoala & Brana 2006).
Threat to endangered species: A study performed in the Peñalara Natural Park, Spain found nonnative Salvelinus fontinalis to negatively affect Iberian frog (see Rana iberica in IUCN Red List of Threatened Species) populations, and they are believed to have played a role in the amphibians major decline (Bosch et al. 2006). Sweden
Reduction in native biodiversity: Populations of Salvelinus fontinalis throughout Sweden have resulted in negative ecological impacts on native species and have even replaced endemic trout in some streams. One specific example consists of brook trout populations inflicting native brown trout (Salmo trutta) with a lower growth rate, delayed maturation, and increased mortality. (FishBase, 2001; Ohlund, 2002).
A study of 193 boreal lakes in Sweden found that introduced S. fontinalis pose a detrimental impact to native brown trout (S. trutta). Twenty percent of brown trout populations exposed to brook trout went extinct versus an only 2% extinction rate in unexposed lakes (Spens et al. 2007). John Muir Wilderness Study Area (United States (USA))
Modification of natural benthic communities: The introduction of trout including Salvelinus fontinalis to naturally fishless Sierra Nevada lakes, specifically in Kings Canyon National Park and John Muir Wilderness, causes changes in the benthic macroinvertabrate and zooplankton communities (Knapp, 2001).
Threat to endangered species: Trout, including Salvelinus fontinalis, introduced to previously fishless lakes throughout California, specifically Kings Canyon National Park and John Muir Wilderness, have caused a significant decline and many extinctions of populations of the endangered mountain yellow-legged frog (see Rana muscosa in IUCN Red List of Threatened Species) (Knapp, 2000; Bradford, 1998; Bradford, 1991; IUCN, 2007). Kings Canyon National Park (United States (USA))
Modification of natural benthic communities: The introduction of trout including Salvelinus fontinalis to naturally fishless Sierra Nevada lakes, specifically in Kings Canyon National Park and John Muir Wilderness, causes changes in the benthic macroinvertabrate and zooplankton communities (Knapp, 2001).
Threat to endangered species: Trout, including Salvelinus fontinalis, introduced to previously fishless lakes throughout California, specifically Kings Canyon National Park and John Muir Wilderness, have caused a significant decline and many extinctions of populations of the endangered mountain yellow-legged frog (see Rana muscosa in IUCN Red List of Threatened Species) (Knapp, 2000; Bradford, 1998; Bradford, 1991; IUCN, 2007). Lake Tahoe (United States (USA))
Competition: Introduced trout including Salvelinis fontinalis threatened Lahontan cutthroat trout (Oncorhynchus clarki henshawi) with extinction in Lake Tahoe in the 1940's (Fuller, 2006). Alaska (United States (USA))
Hybridisation: In Alaska Salvelinus fontinalis is known to hybridise with trout Dolly Varden (Salvelinus malma) (FishBase, 2001). California (United States (USA))
Hybridisation: Non-native Salvelinus fontinalis hybridises with threatened native bull trout (see Salvelinus confluentus in IUCN Red List of Threatened Species) in the Klamath River (Leary et al. 1993).
Modification of natural benthic communities: The introduction of trout including Salvelinus fontinalis to naturally fishless Sierra Nevada lakes, specifically in Kings Canyon National Park and John Muir Wilderness, causes changes in the benthic macroinvertabrate and zooplankton communities (Knapp, 2001).
Reduction in native biodiversity: Introduced trout including Salvelinis fontinalis threatened Lahontan cutthroat trout (Oncorhynchus clarki henshawi) with extinction in Lake Tahoe in the 1940's. S. fontinalis is known to replace native golden trout (Oncorhynchus aguabonita aguabonita) (Fuller, 2006).
Threat to endangered species: Trout, including Salvelinus fontinalis, introduced to previously fishless lakes throughout California, specifically Kings Canyon National Park and John Muir Wilderness, have caused a significant decline and many extinctions of populations of the endangered mountain yellow-legged frog (see Rana muscosa in IUCN Red List of Threatened Species) (Knapp, 2000; Bradford, 1998; Bradford, 1991; IUCN, 2007). Colorado (United States (USA))
Competition: Stocked brook trout (Salvelinus fontinalis) in Black Hollow Creek, Colorado have completely replaced native greenback cutthroat trout (Oncorhynchus clarki stomias) within five years of their introduction (Fuller, 2006).
Reduction in native biodiversity: Salvilinus fontinalis has a negative association with amphibians: tiger salamander (Ambystoma gracile), boreal toad (see Bufo boreas in IUCN Red List of Threatened Species), boreal chorus frog (Pseudacris maculata), and wood frog (Rana sylvatica) in lakes and ponds of Colorado (Dunham et al. 2004). Idaho (United States (USA))
Competition: Research indicates significant evidence of invasive Salvelinus fontinalis influencing populations and facilitating local extinctions of threatened native bull trout (see Salvelinus confluentus in IUCN Red List of Threatened Species) in Idaho (Rieman et al. 2006).
Reduction in native biodiversity: A study indicates a negative effect of nonnative Salvelinus fontinalis on threatened native chinook salmon (Onchorhynchus tshawytsch) in the Columbia River Basin of Idaho (Levin et al. 2002), and native amphibians long-toed salamander (Ambystoma macrodactylum) and Columbia spotted frog (Rana luteiventris) in Idaho (Dunham et al. 2004). Oregon (United States (USA))
Hybridisation: Non-native Salvelinus fontinalis hybridises with threatened native bull trout (see Salvelinus confluentus in IUCN Red List of Threatened Species) in the Columbia River and the Klamath River (Leary et al. 1993).
Reduction in native biodiversity: Brook trout are known to have a negative association with Oregon native amphibians long-toed salamander (Ambystoma macrodactylum), boreal toad (Bufo boreas in IUCN Red List of Threatened Species), Pacific treefrog (Pseudacris regilla),and Columbia spotted frog (Rana luteiventris) (Dunham et al. 2004). Washington (United States (USA))
Reduction in native biodiversity: Effects of introduced Salvelinus fontinalis on native amphibian populations in Washington have sparked conservation efforts in Mount Rainier National Park (Hoffman et al. 2004).
S. fontinalis is found to have a negative association with native amphibians: long-toed salamander (Ambystoma macrodactylum), northwestern salamander (Ambystoma gracile), tailed frog (Ascaphus truel), and cascade frog (see Rana cascadae in IUCN Red List of Threatened Species) (Dunham et al. 2004). Wyoming (United States (USA))
Reduction in native biodiversity: Native Colorado River Basin cutthroat trout Oncorhynchus clarki pleuriticus, is severly threatened, although only petitioned to be but not yet officially endangered, they have been reduced to 1% of their native range in Wyoming primarily as a result of competitive exclusion by introduced Salvelinus fontinalis (Thompson & Rahel 1996). Competition from non-native fish including S. fontinalis is a cause in the decline of indigenous Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri) in Wyoming (Kruse, 1999).
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