Lake salmon, freshwater salmon, sebago salmon, ouananiche (MacCrimmon and Gots 1979), Salmo brevipes Smitt, 1882; Salmo caerulescens Schmidt, 1795; Salmo gloverii Girard, 1854; Salmo goedenii Bloch, 1784; Salmo gracilis Couch, 1865; Salmo hamatus Cuvier, 1829; Salmo hardinii Günther, 1866; Salmo nobilis Olafsen, 1772; Salmo nobilis Pallas, 1814; Salmo ocla Nilsson, 1832; Salmo renatus Lacepède, 1803; Salmo rilla Lacepède, 1803; Salmo salar biennis Berg, 1912; Salmo salar brevipes Smitt, 1882; Salmo salar brevipes natio relictus Berg, 1932; Salmo salar europaeus Payne, Child & Forrest 1971; Salmo salar lacustris Hardin, 1862; Salmo salar nobilis Smitt, 1895; Salmo salar ouananiche McCarthy, 1894; Salmo salar saimensis Seppovaara, 1962; Salmo salar sebago Girard, 1853; Salmo salar tasmanicus Johnston, 1889; Salmo salmo Valenciennes, 1848; Salmo salmulus Walbaum, 1792; Salmo sebago Girard, 1853; Salmo strom Bonnaterre, 1788; Trutta relicta Malmgren, 1863; Trutta salar (Linnaeus, 1758); Trutta salar relicta (Malmgren, 1863)

Maximum length 120 cm (females) – 150 cm (males) (Robins and Ray 1986). Maximum recorded weight 46.8 kg (Daymond 1963). Average size 75 cm long and 4.5 kg after two years at sea (Fay et al. 2006). Modern Great Lakes individuals average 2.7–6.8 kg, with the record standing at 104 cm and 14.8 kg.

The streams to which salmon return to spawn are generally characterized by gradients of 0.2% to 1.4% (Fay et al. 2006). Upon entering freshwater, adult salmon stop feeding and darken in color (Fay et al. 2006). Females choose the nesting site, typically in a well-oxygenated, gravel-bottomed riffle above a pool (Peterson 1978). Water depth at the spawning site is typically 30 to 61 cm with an average water velocity of 60 cm per second (Beland 1984). The female then forms a nest in the substrate (known as a “redd”) by strongly flapping her caudal fin above the sediment. On average, redds are 2.4 meters long and 1.4 meters wide (Bley 1987). Female Atlantic Salmon produce 1,500 to 1,800 eggs per kilogram of body weight, and, once fertilized, these eggs remain buried in about 12 to 20 centimeters of sediment until hatching (Baum and Meister 1971). This spawning process is repeated over the course of one week or more until the spawners are exhausted. While some individuals die after one spawning cycle, the majority survive to spawn at least one more year; very few salmon survive to spawn for three or more years. Lake-run adults may rest in the river for a while after spawning, with some males not returning to the lake until spring.

Peak spawning occurs in late October through November, eggs hatch in late March or April following deposition, and the fry remain buried in the substrate until usually mid-May (Gustafson-Greenwood and Moring 1991; Fay et al. 2006). Over 95% of fry emerge from the substrate at night (Gustafson-Marjanen and Dowse 1983). During this early life stage, the fry’s preferred habitat consists of relatively large and cool rivers with extensive gravel substrate. Young salmon in streams feed on mainly the larvae of aquatic insects, including blackflies, stoneflies, caddisflies, and midges. In late summer, salmon begin to incorporate terrestrial insects into their diet. When these young individuals reach a length of 12.5 to 15 cm (2–3 years), they are ready to migrate out to sea (Schaffer and Elson 1975) or to their parental lake. During migration, smolts may contend with changes in salinity, water temperature, pH, dissolved oxygen, pollution levels, and predator assemblages (Fay et al. 2006). Small individuals at sea, known as postsmolts, feed mainly on euphausiids, amphipods, and small fish (Jutila and Toivonen 1985; Fraser 1987; Hislop and Shelton 1993). As individuals grow, their diet shifts to include a greater proportion of fishes, including smelt, capelin, herring and Alewife, small mackerel, and small cod (Bigelow 1963; Scott and Crossman 1973; Fay et al. 2006).

Lake-run Atlantic Salmon may be found close to shore in the spring, where the water is warmer and food more abundant, but move offshore to feed on Rainbow Smelt (Osmerus mordax) and Alewife (Alosa pseudoharengus) once water temperatures climb above 12°C. Other common prey items include Sculpin, Bloater, and Yellow Perch (Crawford 2001). They may spend 1–2 years in the lake before returning to spawn.

Great Lakes:

For over 100 years, unsuccessful attempts have been made to establish this species within the Great Lakes. Thus far, three different strains of this species have been introduced to the Great Lakes, including an ocean-going population from rivers in the province of Quebec, a landlocked strain from Maine, and a strain from Sweden known as “Gullspang” salmon, which has been landlocked for thousands of years (Emery 1985; Keller et al. 1989; Behmer et al. 1993).

As native Atlantic Salmon populations were first beginning to decline in Lake Ontario between 1867 and 1883, hatcheries stocked juveniles in numerous Lake Ontario tributaries. These attempts failed to reestablish self-sustaining populations (Smith 1896; MacKay 1969). In 1873, failed attempts of introduction by both the American and Canadian governments occurred in multiple locations of Lakes Erie, Michigan, Huron, and Superior (Emery 1985; Keller et al. 1989; Crawford 2001). An unsuccessful stocking of Atlantic Salmon occurred in Lake Ontario in 1867 in an attempt to restore native populations (Schultz 1983).

A landlocked Atlantic Salmon strain was first stocked in Lake Michigan in 1874 (Schultz 1983). In 1876, a failed attempt of introduction occurred in Lake Erie (Parsons 1973), and in 1884 stocking attempts were made in multiple unspecified locations of the Great Lakes (MacCrimmon and Gots 1979). Further stockings were performed in 1910 and 1913 into various Lake Superior and Georgian Bay tributaries (MacCrimmon 1977). Atlantic Salmon was once again introduced to the Great Lakes between 1935 and 1939, and the only self-sustaining population to result from these introductions was in Trout Lake, Ontario, which drains into Lake Huron (MacKay 1969). A total of 743,000 anadromous Atlantic Salmon were stocked in the Lakes between 1873 and 1947 (Parsons 1973).

In 1953, New York State again released Atlantic Salmon into lakes and headwater tributaries of Lake Ontario (Parsons 1973). These introductions were able to support a small recreational fishery but the fish were not self-reproducing (Emery 1985). By 1958, all introduced Atlantic Salmon in the Great Lakes were either extremely rare or extinct (Hubbs and Lagler 1958). For the first time in recent years, the Atlantic Salmon was again introduced to the Great Lakes in 1972 through the release of 20,000 young individuals in the Boyne and Au Sable Rivers (MDNR 2011). Between 1972 and 1978, 2.7 million Atlantic Salmon have been reintroduced into Lake Ontario and approximately another 1.5 million have been introduced into the upper Great Lakes (Crawford 2001). In 1979, unsuccessful introductions occurred in Lakes Michigan, Huron, and Superior (MacCrimmon and Gots 1979; Emery 1985). Collections were reported from Lakes Michigan, Huron, and Superior in 1986, and by 1992, stocked populations were considered to be established in Lake Michigan along the northwestern Indiana coast (Simon et al. 1992).

Between 1983 and 1998, both the United States and Canada continued to stock this species in Lake Ontario, with a combined maximum introduction in 1996 of about 450,000 individuals (Crawford 2001). As of 1998, stocking of this species had ceased in all of the Great Lakes except Lake Ontario and very small numbers (<80,000/year) in Lake Huron (Crawford 2001). In 1999, this species was reported in the Sleeping Bear Dunes National Lakeshore, Leelanau County, Michigan, as well as within the waters of Isle Royal National Park in Lake Superior, Michigan. In 2000, failed stocking attempts were made in Lake Saint Clair, Michigan and in Lake Ontario, New York (Cudmore-Vokey and Crossman 2000).

Great Lakes:

Widespread, with populations overwintering in all five Great Lakes. Populations are sustained by stocking programs (Cudmore-Vokey and Crossman 2000).

This species was native to Lake Ontario and its tributaries up until 1896, but has been extirpated completely (Cudmore-Vokey and Crossman 2000; Crawford 2001). Any individuals currently present in Lake Ontario are the result of reintroductions (Crawford 2001). In 2006, the Lake Ontario Atlantic Salmon restoration program was launched by the Ontario Federation of Anglers and Hunters (OFAH) and the Ontario Ministry of Natural Resources (OMNR) in an attempt to establish reproducing Atlantic Salmon populations in Lake Ontario. In the first five years of the program, more than 2.5 million Atlantic Salmon had been stocked into three tributaries of Lake Ontario (Credit River, Duffins Creek, and Cobourg Brook), and within four years, wild-born Atlantic Salmon were collected in one of the those tributaries for the first time in over a century (OFAH 2011). In 2009, 41 wild Atlantic Salmon were collected from Salmon River in New York, also for the first time in more than a century (Figura 2009). It is estimated that these restocking programs will take an additional 10–15 years for populations to become completely self-sustaining (OFAH 2011). Lake Superior State University continues to stock Atlantic Salmon in the Saint Mary’s River, which travel to Lake Huron and Georgian Bay. In 2012, Atlantic Salmon were recorded to have naturally reproduced for the first time in the Saint Mary’s River (Tucker et al. 2014). Trout Lake, near North Bay, ON in the Lake Huron drainage currently has a small, naturally reproducing population that is the result of stocking (OFAH 2011).

Realized:

Salmonids are known to serve as hosts for a wide range of non-native diseases, such as furunculosis, viral hemorrhagic septicemia (VHS), and whirling disease, as well as parasites, including Philonema oncorhynchi and Ergasilus nerkae (Crawford 2001). Atlantic Salmon with signs of furunculosis have even been released into the St. Marys River intentionally (Behmer et al. 1993). Of all Great Lakes species, native salmonines such as Lake Trout and Brook Trout are most susceptible to introduced diseases (Crawford 2001). As stocking artificially increases the disease and parasite reservoir to which native fish species are exposed, fisheries managers on Lake Ontario and Lake Huron have expressed concern that they may face a repeat of the Lake Michigan bacterial kidney disease (BKD) outbreak if salmon stocking programs exceed their carrying capacity (Rand and Stewart 1998).

Competition has been investigated in a limited number of studies between native and introduced salmonines (Crawford 2001). In Great Lakes tributaries, the larger and more aggressive introduced Atlantic Salmon appears to outcompete smaller native species for limited food, cover, and stream position (Crawford 2001). In open lake experiments, high overlap between Atlantic Salmon and Lake Trout diets has been observed (Negus 1995). Furthermore, a review of 17 published experiments on interspecific competition between juvenile Atlantic Salmon and Great Lakes native fishes found that very few of those studies were designed in a way to show significant effects of interspecific competition (Fausch 1998). This has likely led to a profound underestimation of Atlantic Salmon’s effects on native fish species (Peters 1991).

However, more recent studies have shown limited competitive advantage and dietary/habitat overlap between Atlantic Salmon and other salmonids. In an artificial stream experiment, Brown Trout, Rainbow Trout, Chinook Salmon, and Coho Salmon were all superior competitors to Atlantic Salmon, suggesting that Atlantic Salmon may have little impact on the productivity of those species (Houde et al. 2017). In Lake Ontario tributaries, there was low diet similarity between Chinook Salmon and Atlantic Salmon, suggesting minimal competition (Johnson et al. 2017). In streams in the Lake Ontario watershed, Atlantic Salmon, Rainbow Trout, Chinook Salmon, and Coho Salmon all inhabited distinct habitat types and thus sympatry between the species is likely (Johnson and McKenna 2017). Further, reintroductions of Atlantic Salmon into Lake Ontario tributaries are so far not having any competitive impacts on other fishes (Larocque et al. 2021).  In a small fishery in Lake Huron, stable isotope analysis suggested that despite Atlantic Salmon having a considerable trophic niche overlap with Chinook Salmon and Coho Salmon, it had a lower consumptive demand of prey fishes relative to the other salmon. However, long term impacts of stocking Atlantic Salmon in Lake Huron are unknown (Gerig et al. 2019).

Predation of native forage species by introduced salmonines is a concern, as the stocked Atlantic Salmon are generalist vertebrate predators and have the ability to feed on a wide variety of prey. This is a heightened concern in Great Lakes tributaries where juvenile and stream resident Atlantic Salmon forage on a common supply of native species, including invertebrates and fish (Crawford 2001). In open lakes, salmon feed on introduced Alewife and Rainbow Smelt, as well as native Sculpin, Bloater, and Yellow Perch. As Alewife populations decline, it is predicted that salmonine species will shift their diets to include a greater proportion of native species. This could expose those forage species to excessive mortality, especially if salmon stockings exceed the carrying capacity (Crawford 2001). It is also important to note that Atlantic Salmon health and mortality is significantly impacted by thiamine deficiencies caused by consuming Alewife (Ladago et al. 2020). Stocking of Atlantic Salmon in the Great Lakes may also have unintended impacts on other important recreation fishes. A significant portion of reintroduced Atlantic Salmon diets in Lake Ontario tributaries contained Rainbow Trout eggs, but long term impacts are uncertain (Johnson et al. 2016).

Genetic alteration of Great Lakes native species by introduced salmonines has been observed directly, through hybridization and introgression, and indirectly, associated with declines in population and abundance of natives as a result of intensive stocking (Crawford 2001), but it is unknown if Atlantic Salmon has been involved. Hybridization and introgression between Atlantic Salmon and another Great Lakes introduced species, the Brown Trout (Salmo trutta), is common both in Europe (Payne et al. 1972; Youngson et al. 1992, 1993; Jordan and Verspoor 1993; Hartley 1996; Jansson and Ost 1997) and in North America (Verspoor and Hammar 1991; McGowan and Davidson 1992). In contrast, there are no reported cases of hybridization between the Atlantic and Pacific salmonid species in the wild in North America, South America, New Zealand, or Europe (Waknitz et al. 2002). Hybridization in North American rivers has been observed at significantly higher frequencies than those observed in Europe (Verspoor 1988). Thus, wild hybridization between sympatric salmonines may be much more common and ecologically significant than previously thought (Sorensen et al. 1995).

Due to the multiple distinct genetic strains of Atlantic Salmon that are stocked in a singular location, outbreeding depression is a possible impact. The interbreeding of these different genetic populations with wild salmon can ultimately lead to reduced fitness via the loss of local adaptations and can negatively impact populations (Houde et al. 2015). However, under certain conditions, fitness can instead be increased if a population possesses a beneficial genetic adaptation (Houde et al. 2011). In Norway, introgression of wild and farmed Atlantic Salmon is expected to reduce population productivity and diminish resilience to environmental stressors (Glover et al. 2017).

Introduced salmonines have also been seen to have effects on water chemistry and the physical environment. A massive influx of organic matter and nutrients, as well as contaminants, is transported upstream from lakes to tributaries during spawning migrations (Richey et al. 1975; Bilby et al. 1996, 1998; Cedarholm et al. 1999; Crawford 2001). However, most Atlantic Salmon spawning migrations occur in Lake Ontario tributaries within their historical native range, so their net impact on water chemistry is limited. Spawning salmon have been seen to dig up the redds (nests) of native fish and to otherwise superimpose their redds on native fish habitat. Such physical alterations impart community level effects on the abundance and distribution of native fish in affected tributaries (Fukushima et al. 1998; Crawford 2001). In addition, the native Brook Trout (Salvelinus fontinalis) typically buries its eggs in redds that are shallower than Atlantic salmon redds (DeVries 1997). Subsequent Atlantic Salmon spawning can lead to the displacement of Brook Trout embryos (Fukushima et al. 1998).

Potential:

Wild and farmed Atlantic Salmon in other parts of the United States and the world are host to a variety of diseases and parasites that could pose a threat to native and introduced salmonids in the Great Lakes. This species is susceptible to the Piscine reovirus (PRV), the Infectious haematopoietic necrosis virus (IHNV) (Morton et al. 2016), and the Salmonid alphavirus (SAV). SAV can infect both Atlantic Salmon and Rainbow Trout, leading to pancreatic disease and sleeping disease that have high mortality rates. SAV is currently only in Europe and trade of salmonids is banned unless tested for the virus (Deperasinska et al. 2018). In British Columbia, Canada, there is a high prevalence of Piscine orthoreovirus (Strain PRV-1) in farmed salmon. Piscine orthoreovirus can pose a risk of developing heart and skeletal muscle inflammation (HSMI) in wild Atlantic Salmon, Rainbow Trout, and other salmonids (Di Cicco et al. 2018). However, the long term stability of the virus in natural environments is unknown (Poliniski et al. 2020).  An initial study in Norway found little evidence that freshwater salmonids contain Piscine orthoreovirus (Garseth and Biering 2018).

In Norway, salmon gill poxvirus (SGPV) in fresh and saltwater causes apoptosis and immune impairment in Atlantic Salmon (Gjessing et al. 2017). A North American variant of SGPV was found in New Brunswick, Canada. However, the impact or significance of its discovery in regard to salmonids in Canada is uncertain (LeBlanc et al. 2019).
Atlantic Salmon are a host to ectoparasite Gyrodactylus salaris, which can infect many salmonid species and has devastated Atlantic Salmon stocks in Norway (Soleng and Bakke 1997; Sanddodden et al. 2018).

There is little or no evidence to support that Salmo salar has significant socio-economic impacts in the Great Lakes outside of its native range.

Potential:

Atlantic Salmon are host to a variety of parasites and diseases that could impact fisheries and recreation, however, no outbreaks or significant impacts have been reported in the Great Lakes.

Salmo salar has a high beneficial effect in the Great Lakes outside of its native range.

The Atlantic Salmon is renowned among anglers and is a highly prized food fish. It is for these reasons that stocking attempts in the upper Great Lakes have been made for more than a century (Crawford 2001). Even with the limited establishment success that has been experienced, MacCrimmon (1977) argues that attempts to establish this species in the Great Lakes will probably never cease.

Atlantic Salmon introductions into the St. Marys River from West Grand Lake, Maine continue to support local sport fisheries and attract anglers from all over the country (Behmer et al. 1993). Though once native to Lake Ontario, the Lake Ontario Atlantic Salmon Restoration Program is an ongoing project with the aim of re-establishing self-reproducing Atlantic Salmon populations in Lake Ontario tributaries. As part of this project, over 2.7 million individuals have been stocked as of early 2011 (OFAH 2011). Even though Atlantic salmon are a relatively minor component of the Lake Ontario fishery, they contribute to the diversity of trophy salmon and trout available to anglers. (NYSDEC 2020).

Atlantic Salmon historically have a high commercial value in the Great Lakes region (Kerr 2010). At present, numerous aquaculture facilities support the intensive stocking programs in Lake Huron and Lake Ontario in order to re-establish self-sustaining populations of Atlantic Salmon (USFWS/GLFC 2010). While many of the commercial fisheries in the Great Lakes have reduced or ceased production following the decline in Atlantic Salmon populations, some First Nations fisheries are still active under the Indigenous Food, Social, and Ceremonial (FSC) licensing program in Canada as Atlantic Salmon have significant social, economic, and cultural value (Myrvold et al. 2019).

In the United States and its territories, the importation or transportation of species in the family Salmonidae is prohibited unless otherwise stated (18 U.S.C. 42 (Lacey Act)). In Canada, the use or possession of fish as live bait in any province other than from which it was taken is prohibited (SOR/93-55). This species is not on the Illinois Aquatic Life Approved Species List and is illegal to be imported or possessed alive without a permit (515 ILCS 5/20-90). This species is considered nonnative in Minnesota but is not subject to regulation under invasive species statutes, however, it may have relevant fishing and hunting regulations (Statute 84D.07).  It is illegal to bring any live fish into Ontario for use as bait (SOR/2007-237). In Quebec, both the use of this species as bait and the sale of dead fish of this species or its hybrids is prohibited (CQLR c C-61.1, r7 SOR/90-214). It is a restricted species in Wisconsin, where there is a ban on the transport, transfer and introduction of this species, but possession is allowed (Chapter NR 40, Wis. Adm. Code).

Control
Biological

There are no known biological control methods for this species.

Physical

There are no known physical control methods for this species.

Chemical

There are no known chemical control methods specific to this species. General piscicides (such as rotenone) may be used for control, but expect significant kill of non-target species.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.