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   Salvelinus namaycush (fish)   
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    Taxonomic name: Salvelinus namaycush (Walbaum in Artedi, 1792)
    Synonyms: Cristivomer namaycush (Walbaum, 1792), Cristovomer namayacush (Walbaum, 1792), Salmo amethystinus (Mitchill, 1818, Salmo amethystus (Mitchill, 1818, Salmo confinis (DeKay, 1842), Salmo ferox (Perley, 1852), Salmo namaycush (Walbaum, 1792), Salmo pallidus (Rafinesque, 1817), Salvelinus namaycush (Walbaum, 1792)
    Common names: akalukpik (Inuktitut-Alaska, USA), Amerikanische Seeforelle (German-Switzerland), Amerikanischer seesaibling (German-Germany), Amerikansk søørred (Danish-Denmark), Canadarødding (Danish-Denmark), Canadaröding (Swedish-Sweden), Canadarøding (Danish-Denmark), Canadaröye (Norwegian-Norway), Canadarøye (Norwegian-Norway), Col-lic-puk (Inuktitut-Alaska, USA), cristivomer (French-France), Great Lakes char (English-Canada), Great Lakes trout (English-Canada), grey trout (English-Canada), harmaanieriä (Finnish-Finland), hupin (British Columbia, Canada), iclook (Inuktitut-Greenland), idlorak (Inuktitut-Canada), ihok (Inuktitut-Canada), iiuuraq (Inuktitut-Canada), ikalukpik (Inuktitut-United States), ikhiloktok (Inuktitut-Canada), ikhloark (Inuktitut-Canada), ilortoq (Inuktitut-Canada), iqluq (Inuktitut-Greenland), ishioraliktâq (Inuktitut-Canada), islorak (Inuktitut-Canada), isok (Inuktitut-Canada), isuuq (Inuktitut-Canada), isuuqiaq (Inuktitut-Canada), isuuqiq (Inuktitut-Canada), isuuraaryuk (Inuktitut-Canada), isuuraq (Inuktitut-Canada), ivitaruk (Inuktitut-Canada), kanadarødding (Danish-Denmark), kanadaröding (Swedish-Sweden), kanadarøding (Danish-Denmark), keyteeleek (Inuktitut-Canada), k'wit'thet (Salish-Canada), k'wsech (Salish-Canada), lake charr (English-Canada), lake trout (English-Canada, United States, United Kingdom), laker (English-Canada), landlocked salmon (English-Canada), Mackinaw trout (English-Canada, New Zealand), Masamacush (English-Canada), milaqkkâyoq (Inuktitut-Canada), mountain trout (English-Canada), murta (Icelandic-Iceland), naaqtuuq (Inuktitut-Canada), näluarryuk (Inuktitut-Canada), namaycush (English-Canada, United Kingdom), namekus (Cree-Canada), nauktoq (Inuktitut-Canada), nemakos (Cree-Canada), nemeks (Cree-Canada), némèkus (Cree-Canada), omble d'Amérique (French-France), omble du Canada (French-France), salmon trout (English-Canada), salvelino-lacustre (Portuguese-Portugal), severoamerikanskiy kristivomer (Russian-Russian Federation), shamet skelex (Salish-Canada), shmexwalsh (Salish-Canada), sigguayaq (Inuktitut-Canada), siscowet (English-Canada, United States), siscowet (English-United States, Canada), siuktuuk (Inuktitut-Canada), siuyuktuuq (Inuktitut-Canada), siven obrovký (Czech-Czech Republic), sivon velký (Slovak-Slovakia), sk'wel'eng's schaanexw (Salish-Canada), slhop' schaanexw (Salish-Canada), spak'ws schaanexw (Salish-Canada), taque (English-Canada), togue (English-Canada, United Kingdom), touladi (French-Canada, France, United Kingdom), trota di lago americana (Italian-Italy), trucha lacustre (Spanish-Spain), truite de lac d'Amérique (French-France), truite grise (French-Canada), truta-do-lago (Portuguese-Portugal)
    Organism type: fish
    Salvelinus namaycush is a freshwater fish of the trout family, found primarily in lakes and large rivers worldwide. The distribution is broad due to the sport fishing industry and the demand for Salvelinus namaycush. In many of the introduced locations Salvelinus namaycush is an invasive species and reduces native biodiversity through competition and predation of endemic species. There have been some successful attempts to control Salvelinus namaycush using gillnetting and trapping.
    Cream coloured spots are found on the head and body, as well as the dorsal and caudal fins of Salvelinus namaycush. The average weight of S. namaycush is about 3 kg, but individuals will grow to up 27 kg if long lived. Average length of S. namaycush varies from 45 to 68 cm. The body is a slate grey to greenish with a lighter underside and a deeply forked caudal fin. Fins lower on the body are orange-red with a white edge. Breeding males will develop a dark stripe on their sides temporarily (Lenart, 2001).
    Similar Species
    Salvelinus fontinalis

    Occurs in:
    estuarine habitats, lakes, water courses
    Habitat description
    Residing exclusively in freshwater, Salvelinus namaycush is found in lakes and rivers of varying sizes. The ability of S. namaycush to inhabit almost benthic-like environments gives it an upper hand in competition with other fish species. Within the water column, S. namaycush is found at both deep and shallow depths depending on the location and time of year as well as stage of development. S. namaycush prefers temperatures below 13°C and is rarely found in lakes with pH less than 5.2 (NatureServe, 2008)
    General impacts
    The introduction of the invasive trout species Salvelinus namaycush has had detrimental effects on native biodiversity worldwide. Many various species of fish are affected not only by competition but by predation as well (Fuller, 2007). In the United States many endemic species are at risk due to the presence of S. Namaycush (Ruzycki et al. 2001) including the rare Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) (Fuller, 2007).
    Salvelinus namaycush was an important commercial fish stock in the US Great Lakes in the 1950's, but has since gone on the decline due to predation factors from sea lamprey. S. Namaycush remains a valuable sport fish for anglers worldwide (Lenart, 2001).
    Salvelinus namaycush are particularly susceptible to pollution, including but not limited to insecticides (FishBase, 2008). Hybrid crosses between female S. namaycush and male Salvelinus fontinalis called splakes, have been introduced into many areas of North America because of their ability to grow very quickly (Nova Scotia Fisheries and Aquaculture, Inland Fisheries Division. 2007).
    Geographical range
    Native range: Canada, United States
    Known introduced range: Argentina, Austria, Bolivia, Czech Republic, Denmark, Finland, France, Germany, Italy, Japan, Morocco, New Zealand, Norway, Peru, Slovakia, Spain, Sweden, Switzerland, United Kingdom, United States
    Introduction pathways to new locations
    Stocking: Salvelinus namaycush is primarily bred and stocked for recreational fisheries (Fuller, 2007).
    Stocking: Salvelinus namaycush is primarily bred and stocked for recreational fisheries worldwide (Fuller, 2007).

    Local dispersal methods
    Natural dispersal (local): The dispersal of Salvelinus namaycush downstream and into new tributaries through regular stocking upstream is bound to occur (Hesthagen & Sandlund 2007).
    Management information
    Preventative measures: The use of potentially invasive alien species for aquaculture and their accidental release/or escape can have negative impacts on native biodiversity and ecosystems. Hewitt et al, (2006) Alien Species in Aquaculture: Considerations for responsible use aims to first provide decision makers and managers with information on the existing international and regional regulations that address the use of alien species in aquaculture, either directly or indirectly; and three examples of national responses to this issue (Australia, New Zealand and Chile). The publication also provides recommendations for a ‘simple’ set of guidelines and principles for developing countries that can be applied at a regional or domestic level for the responsible management of Alien Species use in aquaculture development. These guidelines focus primarily on marine systems, however may equally be applied to freshwater.

    Copp et al, (2005) Risk identification and assessment of non-native freshwater fishes presents a conceptual risk assessment approach for freshwater fish species that addresses the first two elements (hazard identification, hazard assessment) of the UK environmental risk strategy. The paper presents a few worked examples of assessments on species to facilitate discussion. The electronic Decision-support tools- Invasive-species identification tool kits that includes a freshwater and marine fish invasives scoring kit are made available on the Cefas (Centre for Environment, Fisheries & Aquaculture Science) page for free download (subject to Crown Copyright (2007-2008)).

    Physical: Gillnetting and trapping were deemed the most suitable management techniques for the control of Salvelinus namaycush in Yellowstone Lake (Kaeding et al. 1996). Electrofishing has also been proven to be effective in managing populations of S. namaycush, and is done yearly in Yellowstone Lake (Greater Yellowstone Science Learning Center. 8 Jan 2008).

    Feeding on organisms from freshwater sponges to plankton, Salvelinus namaycush predates on a variety of underwater life. Organisms such as crustaceans, insects, fish and even small mammals are part of the diet of S. namaycush. When in the juvenile state, S. namaycush feeds almost exclusively on invertebrates. It was discovered that individuals which feed primarily on plankton grow slower, mature earlier at smaller sizes, die sooner and attain a smaller maximum size than those who predominately eat fish (FishBase, 2008). In larger lakes, S. namaycush is predominately piscivorous, where as in a smaller lake with less fish forage potential the predominate diet consists of crustaceans and plankton (Nova Scotia Fisheries and Aquaculture, Inland Fisheries Division. 2007).
    Like many other aquatic species, Salvelinus namaycush fertilizes eggs externally, but unlike other species do not construct a 'redd' or nest. The act of spawning occurs predominately at night; where males will approach a female, press against her sides and quiver. During this act the females' eggs fall into rocky outcroppings beneath her after being fertilized by the male. This act of courting is repeated until all the eggs of the female are released. Occasionally, up to seven males and three females may interact together in a single spawning act. Spawning for S. Namaycush occurs annually in the southern range while only occurring every other year in more northern limits (FishBase, 2008).
    Lifecycle stages
    Egg development for Salvelinus namaycush, depending on temperature, takes between 15 and 21 weeks to reach hatching which occurs between mid-February and late March (FishBase, 2008). The fry do not emerge from the crevices until a month after "hatching" in order to give time for the yolk sacs to absorb. The juveniles then fill their swim bladders near the surface and descend to deeper water where they remain for two or three years, which may be survival related since adults are found higher up in the water column and are known to be cannibalistic (Nova Scotia Fisheries and Aquaculture, Inland Fisheries Division, 2007).
    Reviewed by: Pam Fuller USGS/BRD, Nonindigenous Aquatic Species Program. Florida Integrated Science Center. USA
    Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
    Last Modified: Thursday, 21 May 2009

ISSG Landcare Research NBII IUCN University of Auckland