Great Lakes Aquatic Nonindigenous Species List
| Year Sighted | Species | Common Name | Type | Endemic Region | Location of First Sighting | Vector |
|---|---|---|---|---|---|---|
| 1840 | Rumex obtusifolius | bitter dock | Plant | Eurasia | Widespread | Unknown |
| 1843 | Echinochloa crusgalli | barnyard grass | Plant | Eurasia | Widespread | Release, deliberate |
| 1843 | Solanum dulcamara | bittersweet nightshade | Plant | Eurasia | Widespread | Release, deliberate |
| 1843 | Polygonum persicaria | lady's thumb | Plant | Eurasia | Widespread | Unknown |
| 1843 | Mentha piperita | peppermint | Plant | Eurasia | Widespread | Release, deliberate |
| 1843 | Conium maculatum | poison hemlock | Plant | Eurasia | Widespread | Release, deliberate |
| 1843 | Poa trivalis | rough-stalked meadow grass | Plant | Eurasia | Widespread | Release, deliberate |
| 1843 | Mentha spicata | spearmint | Plant | Eurasia | Widespread | Release, deliberate |
| 1847 | Rorippa nasturtium aquaticum | water cress | Plant | Eurasia | Lake Ontario | Release, deliberate |
| 1860 | Elimia virginica | snail | Mollusk | Atlantic NA | Erie Canal | Canals |
| 1862 | Juncus gerardii | black-grass rush | Plant | Atlantic NA | Chicago | Shipping, Solid Ballast |
| 1864 | Najas marina | spiny naiad | Plant | Eurasia | Lake Ontario drainage | Shipping, Solid Ballast |
| 1865 | Sonchus arvensis | field sow thistle | Plant | Eurasia | Central, NY | Release, unintentional |
| 1866 | Carex disticha | sedge | Plant | Eurasia | Lake Ontario | Shipping, Solid Ballast |
| 1867 | Chenopodium glaucum | oak leaved goose foot | Plant | Eurasia | Lake Ontario drainage | Railroads and Highways |
| 1869 | Lythrum salicaria | purple loosestrife | Plant | Eurasia | Lake Ontario | Canals |
| 1871 | Bithynia tentaculata | faucet snail | Mollusk | Eurasia | Lake Michigan | Shipping, Solid Ballast |
| 1873 | Alosa pseudoharengus | alewife | Fish | Atlantic NA | Lake Ontario | Canals |
| 1873 | Oncorhynchus tshawytscha | chinook salmon | Fish | Pacific | Widespread | Release, deliberate |
| 1874 | Epilobium hirsutum | great hairy willow herb | Plant | Eurasia | Lake Ontario | Release, unintentional |
| 1876 | Oncorhynchus mykiss | rainbow trout | Fish | Pacific | Lake Huron drainage | Release, deliberate |
| 1878 | Carassius auratus | goldfish | Fish | Asia | Widespread | Release, unintentional |
| 1879 | Cyprinus carpio | common carp | Fish | Ponto-Caspian | Widespread | Release, deliberate |
| 1879 | Potamogeton crispus | curlyleaf pondweed | Plant | Eurasia | Lake Ontario drainage | Release, deliberate |
| 1880 | Typha angustifolia | narrow leaved cattail | Plant | Eurasia | Lake Ontario | Canals |
| 1882 | Lysimachia nummularia | moneywort | Plant | Eurasia | Lake Ontario | Release, deliberate |
| 1882 | Alopecurus geniculatus | water foxtail | Plant | Eurasia | Lake Erie | Release, deliberate |
| 1883 | Salmo trutta | brown trout | Fish | Eurasia | Lake Michigan drainage | Release, deliberate |
| 1884 | Rorippa sylvestris | creeping yellow cress | Plant | Eurasia | Lake Ontario | Shipping, Solid Ballast |
| 1884 | Agrostis gigantea | redtop | Plant | Eurasia | Lake Superior | Release, deliberate |
| 1886 | Salix fragilis | crack willow | Plant | Eurasia | Widespread | Release, deliberate |
| 1886 | Salix purpurea | purple willow | Plant | Eurasia | Widespread | Release, deliberate |
| 1886 | Myosotis scorpioides | true forgot-me-not | Plant | Eurasia | Lake Ontario | Release, deliberate |
| 1886 | Salix alba | white willow | Plant | Eurasia | Widespread | Release, deliberate |
| 1886 | Iris pseudacorus | yellow flag | Plant | Eurasia | Lake Ontario | Release, deliberate |
| 1892 | Lycopus asper | western water horehound | Plant | Mississippi R. | Lake Erie | Release, unintentional |
| 1893 | Puccinellia distans | weeping alkali grass | Plant | Eurasia | Lake Ontario | Shipping, Solid Ballast |
| 1894 | Stellaria aquatica | giant chickweed | Plant | Eurasia | Lake St. Clair | Unknown |
| 1895 | Juncus compressus | flattened rush | Plant | Eurasia | Lake Ontario drainage | Release, unintentional |
| 1895 | Pisidium moitessierianum | pea clam | Mollusk | Eurasia | Lake Superior | Shipping, Solid Ballast |
| 1896 | Carex flacca | sedge | Plant | Eurasia | Detroit River | Unknown |
| 1897 | Valvata piscinalis | European valve snail | Mollusk | Eurasia | Lake Ontario | Shipping, Solid Ballast |
| 1897 | Pisidium amnicum | pea clam | Mollusk | Eurasia | Lake Ontario | Shipping, Solid Ballast |
| 1901 | Radix auricularia | European ear snail | Mollusk | Eurasia | Lake Michigan | Release, unintentional |
| 1901 | Rumex longifolius | yard dock | Plant | Eurasia | Lake Superior | Release, deliberate |
| 1902 | Aeromonas salmonicida | furunculosis | Other Invertebrate | Unknown | Unknown | Release, unintentional |
| 1902 | Sonchus arvensis var. glabrescens | smooth field sow thistle | Plant | Eurasia | Lake Erie | Release, unintentional |
| 1903 | Lycopus europaeus | European water horehound | Plant | Eurasia | Lake Ontario | Shipping, Solid Ballast |
| 1905 | Butomus umbellatus | flowering rush | Plant | Eurasia | Detroit River | Shipping, Solid Ballast |
| 1906 | Viviparus georgianus | banded mystery snail | Mollusk | Mississippi R. | Lake Michigan | Aquarium release |
| 1912 | Impatiens glandulifera | Indian balsam | Plant | Asia | Lake Huron | Release, deliberate |
| 1912 | Osmerus mordax | rainbow smelt | Fish | Atlantic NA | Lake Michigan drainage | Release, deliberate |
| 1913 | Alnus glutinosa | black alder | Plant | Eurasia | Widespread | Release, deliberate |
| 1913 | Lysimachia vulgaris | garden loosetrife | Plant | Eurasia | Lake Ontario | Release, deliberate |
| 1913 | Rhamnus frangula | glossy buckthorn | Plant | Eurasia | lower Great Lakes, Ontario | Release, deliberate |
| 1915 | Mentha gentilis | creeping whorled mint | Plant | Eurasia | Lake Ontario | Release, deliberate |
| 1915 | Veronica beccabunga | European brookline | Plant | Eurasia | Lake Ontario | Shipping, Solid Ballast |
| 1916 | Pisidium henslowanum | henslow's pea clam | Mollusk | Eurasia | Lake Ontario | Shipping, Solid Ballast |
| 1916 | Pluchea odorata var. purpurescens | salt-marsh fleabane | Plant | Atlantic NA | Lake Erie drainage | Release, unintentional |
| 1918 | Gillia altilis | snail | Mollusk | Atlantic NA | Lake Ontario drainage | Canals |
| 1922 | Juncas inflexus | rush | Plant | Eurasia | Lake Ontario drainage | Unknown |
| 1923 | Gambusia affinis | western mosquitofish | Fish | Mississippi R. | Lake Michigan drainage | Release, deliberate |
| 1924 | Sphaerium corneum | fingernail clam | Mollusk | Eurasia | Lake Ontario drainage | Shipping, Ballast Water |
| 1925 | Marsilea quadrifolia | European water clover | Plant | Eurasia | Lake Ontario drainage | Release, deliberate |
| 1926 | Enteromorpha intestinalis | green alga | Benthic Alga | Atlantic NA | Lake Ontario | Release, unintentional |
| 1927 | Acentropus niveus | aquatic moth | Other Invertebrate | Eurasia | St Lawrence R, Montreal | Release, unintentional |
| 1928 | Noturus insignis | margined madtom | Fish | Atlantic NA | Lake Ontario drainage | Canals |
| 1928 | Lepomis microlophus | redear sunfish | Fish | southern U.S. | Lake Michigan drainage | Release, deliberate |
| 1929 | Lepomis humilis | orange spotted sunfish | Fish | Mississippi R. | Lake Erie drainage | Canals |
| 1930 | Nymphoides peltata | yellow floating heart | Plant | Eurasia | Lake Erie drainage | Release, unintentional |
| 1931 | Cipangopaludina chinensis malleata | Oriental mystery snail | Mollusk | Asia | Niagara River | Aquarium release |
| 1932 | Najas minor | minor naiad | Plant | Eurasia | Lake Erie drainage | Release, deliberate |
| 1933 | Oncorhynchus kisutch | coho salmon | Fish | Pacific | Lake Erie | Release, deliberate |
| 1933 | Craspedacusta sowerbyi | freshwater jellyfish | Other Invertebrate | Asia | Lake Erie drainage | Release, unintentional |
| 1934 | Lophopodella carteri | bryozoan | Other Invertebrate | Asia | Lake Erie | Canals |
| 1935 | Cabomba caroliniana | fanwort | Plant | Southern U.S. | Lake Michigan drainage | Aquarium release |
| 1936 | Sparganium glomeratum | bur reed | Plant | Eurasia | Lake Superior | Unknown |
| 1938 | Actinocyclus normanii fo. subsalsa | diatom | Phytoplankton | Eurasia | Lake Ontario | Shipping, Ballast Water |
| 1938 | Diatoma ehrenbergii | diatom | Phytoplankton | Widespread | Lake Michigan | Shipping, Ballast Water |
| 1938 | Stephanodiscus binderanus | diatom | Phytoplankton | Eurasia | Lake Michigan | Shipping, Ballast Water |
| 1939 | Misgurnus anguillicaudatus | Oriental weatherfish | Fish | Asia | Lake Huron drainage | Release, unintentional |
| 1940 | Cipangopaludina japonica | Oriental mystery snail | Mollusk | Asia | Lake Erie | Release, deliberate |
| 1940 | Glyceria maxima | reed sweet-grass | Plant | Eurasia | Lake Ontario | Release, deliberate |
| 1943 | Tanysphyrus lemnae | aquatic weevil | Other Invertebrate | Eurasia | Unknown | Unknown |
| 1946 | Cyclotella pseudostelligera | diatom | Phytoplankton | Widespread | Lake Michigan | Shipping, Ballast Water |
| 1946 | Stephanodiscus subtilis | diatom | Phytoplankton | Eurasia | Lake Michigan | Shipping, Ballast Water |
| 1950 | Oncorhynchus nerka | kokanee | Fish | Pacific NA | Lake Ontario drainage | Release, deliberate |
| 1950 | Cirsium palustre | marsh thistle | Plant | Eurasia | Lake Superior | Unknown |
| 1950 | Potamothrix bedoti | oligochaete | Annelid | Ponto-Caspian | Lake Ontario | Unknown |
| 1950 | Pluchea odorata var. succulenta | salt-marsh fleabane | Plant | Atlantic NA | Lake Ontario drainage | Unknown |
| 1950 | Phenacobius mirabilis | suckermouth minnow | Fish | Mississippi R. | Lake Erie drainage | Canals |
| 1950 | Morone americana | white perch | Fish | Atlantic NA | Lake Ontario | Canals |
| 1951 | Branchiura sowerbyi | oligochaete | Annelid | Asia | Lake Michigan drainage | Release, unintentional |
| 1951 | Carex acutiformis | swamp sedge | Plant | Eurasia | Lake Michigan drainage | Unknown |
| 1952 | Myriophyllum spicatum | Eurasian watermilfoil | Plant | Eurasia | Lake Erie | Aquarium release |
| 1952 | Potamothrix moldaviensis | oligochaete | Annelid | Ponto-Caspian | Lake Ontario | Unknown |
| 1956 | Cordylophora caspia | hydroid | Other Invertebrate | Ponto-Caspian | Lake Erie | Release, unintentional |
| 1956 | Oncorhynchus gorbuscha | pink salmon | Fish | Pacific NA | Lake Superior | Release, unintentional |
| 1958 | Eurytemora affinis | calanoid copepod | Zooplankton (crustacean) | Widespread | Lake Ontario | Shipping, Ballast Water |
| 1959 | Pisidium supinum | humpback pea clam | Mollusk | Europe | Lake Ontario | Shipping, Ballast Water |
| 1959 | Lasmigona subviridis | mussel | Mollusk | Atlantic NA | Lake Ontario drainage | Canals |
| 1959 | Trapa natans | water chestnut | Plant | Eurasia | Lake Ontario drainage | Aquarium release |
| 1960 | Polygonum caespitosum var. longisetum | Bristly Lady's Thumb | Plant | E. Asia | Lake Erie drainage | Unknown |
| 1960 | Glugea hertwigi | protozoan | Other Invertebrate | Eurasia | Lake Erie | Release, unintentional |
| 1962 | Thalassiosira weissflogii | diatom | Phytoplankton | Widespread | Detroit River | Shipping, Ballast Water |
| 1962 | Lepisosteus platostomus | shortnose gar | Fish | Mississippi R. | Lake Michigan drainage | Canals |
| 1963 | Skeletonema potamos | diatom | Phytoplankton | Widespread | Lake Erie drainage | Shipping, Ballast Water |
| 1964 | Cyclotella atomus | diatom | Phytoplankton | Widespread | Lake Michigan | Shipping, Ballast Water |
| 1964 | Cyclotella cryptica | diatom | Phytoplankton | Widespread | Lake Michigan | Shipping, Ballast Water |
| 1964 | Cyclotella woltereki | diatom | Phytoplankton | Widespread | Lake Michigan | Shipping, Ballast Water |
| 1964 | Chroodactylon ramosum | red alga | Benthic Alga | Atlantic Ocean | Lake Erie | Shipping, Ballast Water |
| 1964 | Bangia atropurpurea | red alga | Benthic Alga | Atlantic NA | Lake Erie | Shipping |
| 1965 | Potamothrix vejdovskyi | oligochaete | Annelid | Ponto-Caspian | Lake Erie | Shipping? Ballast Water? |
| 1966 | Epilobium parviflorum | small flowered hairy willow herb | Plant | Eurasia | Lake Michigan drainage | Unknown |
| 1966 | Eubosmina coregoni | waterflea | Zooplankton (crustacean) | Eurasia | Lake Michigan | Shipping, Ballast Water |
| 1967 | Skistodiaptomus pallidus | calanoid copepod | Zooplankton (crustacean) | Mississippi R. | Lake Ontario | Release, unintentional |
| 1968 | Dugesia polychroa | flatworm | Other Invertebrate | Europe | Lake Ontario | Shipping, Ballast Water |
| 1968 | Myxobolus (Myxosoma) cerebralis | salmonid whirling disease | Other Invertebrate | Unknown | Lake Erie drainage | Release, unintentional |
| 1969 | Solidago sempervirens | seaside goldenrod | Plant | Atlantic NA | Lake Michigan | Release, unintentional |
| 1971 | Enneacanthus gloriosus | bluespotted sunfish | Fish | Atlantic NA | Lake Ontario drainage | Aquarium release |
| 1972 | Cyclops strenuus | copepod | Zooplankton (crustacean) | Hudson Bay | Lake Superior | Canals (water diversion) |
| 1972 | Hydrocharis morsus-ranae | European frogbit | Plant | Eurasia | Lake Ontario | Release, unintentional |
| 1973 | Skeletonema subsalsum | diatom | Phytoplankton | Eurasia | Lake Erie | Shipping, Ballast Water |
| 1973 | Thalassiosira guillardii | diatom | Phytoplankton | Widespread | Lake Erie | Shipping, Ballast Water |
| 1973 | Thalassiosira pseudonana | diatom | Phytoplankton | Widespread | Lake Erie drainage | Shipping, Ballast Water |
| 1973 | Nitocra hibernica | harpacticoid copepod | Benthic Crustacean | Eurasia | Lake Ontario | Shipping, Ballast Water |
| 1975 | Renibacterium (Corynebacterium) salmoninarum | Bacterial Kidney Disease | Bacteria | Unknown | L. Superior | Release, unintentional |
| 1975 | Lotus corniculatus | birdsfoot trefoil | Plant | Eurasia | Lake Superior | Release, deliberate |
| 1975 | Sphacelaria fluviatilis | brown alga | Benthic Alga | Asia | Lake Michigan drainage | Aquarium release |
| 1975 | Sphacelaria lacustris | brown alga | Benthic Alga | Unknown | Lake Michigan | Shipping, Ballast Water |
| 1975 | Hymenomonas roseola | cocco-lithophorid alga | Phytoplankton | Eurasia | Lake Huron | Shipping, Ballast Water |
| 1978 | Biddulphia laevis | diatom | Phytoplankton | Widespread | Lake Michigan | Shipping, Ballast Water |
| 1978 | Chaetoceros hohnii | diatom | Phytoplankton | Unknown | Lake Huron | Shipping, Ballast Water |
| 1978 | Thalassiosira lacustris | diatom | Phytoplankton | Eurasia | Lake Erie | Shipping, Ballast Water |
| 1979 | Notropis buchanani | ghost shiner | Fish | Mississippi R. | Lake St. Clair drainage | Bait release |
| 1979 | Enteromorpha prolifera | green alga | Benthic Alga | Atlantic NA | Lake St. Clair drainage | Unknown |
| 1980 | Corbicula fluminea | Asiatic clam | Mollusk | E. Asia | Lake Erie | Aquarium release |
| 1980 | Ripistes parasita | oligochaete | Annelid | Eurasia | Lake Huron | Shipping, Ballast Water |
| 1980 | Daphnia galeata galeata | waterflea | Zooplankton (crustacean) | Eurasia | Lake Erie | Shipping, Ballast Water |
| 1982 | Lupinus polyphyllus | lupine | Plant | Eurasia | Lake Superior | Release, unintentional |
| 1982 | Bythotrephes longimanus | spiny waterflea | Zooplankton (crustacean) | Eurasia | Lake Ontario | Shipping, Ballast Water |
| 1983 | Nitellopsis obtusa | green alga | Phytoplankton | Eurasia | Lake St. Clair | Shipping, Ballast Water |
| 1983 | Gianius (Phallodrilus) aquaedulcis | oligochaete | Annelid | Europe | Niagara River | Shipping, Ballast Water |
| 1985 | Salmincola lotae | copepod | Zooplankton (crustacean) | Eurasia | Lake Superior | Unknown |
| 1986 | Gymnocephalus cernuus | Eurasian ruffe | Fish | Ponto-Caspian | Lake Superior | Shipping, Ballast Water |
| 1986 | Apeltes quadracus | fourspine stickleback | Fish | Atlantic NA | Lake Superior | Shipping, Ballast Water |
| 1988 | Thalassiosira baltica | diatom | Phytoplankton | Europe | Lake Ontario | Shipping, Ballast Water |
| 1988 | Argulus japonicus | parasitic copepod | Zooplankton (crustacean) | Asia | Lake Michigan | Aquarium release |
| 1988 | Bosmina maritima | waterflea | Zooplankton (crustacean) | Eurasia | Lake Erie | Shipping, Ballast Water |
| 1988 | Dreissena polymorpha | zebra mussel | Mollusk | Ponto-Caspian | Lake St. Clair | Shipping, Ballast Water |
| 1989 | Dreissena bugensis | quagga mussel | Mollusk | Ponto-Caspian | Lake Ontario | Shipping, Ballast Water |
| 1989 | Scardinius erythrophthalmus | rudd | Fish | Eurasia | Lake Ontario | Bait release |
| 1990 | Neogobius melanostomus | round goby | Fish | Ponto-Caspian | St. Clair River | Shipping, Ballast Water |
| 1990 | Proterorhinus marmoratus | tubenose goby | Fish | Ponto-Caspian | St. Clair River | Shipping, Ballast Water |
| 1991 | Potamopyrgus antipodarum | New Zealand mud snail | Mollusk | Australasia | Lake Ontario | Shipping, Ballast Water |
| 1992 | Acanthostomum sp. | digenean fluke | Other Invertebrate | Eurasia | Lake Superior | Shipping, Ballast Water |
| 1992 | Ichthyocotylurus pileatus | digenean fluke | Other Invertebrate | Ponto-Caspian | Lake Superior | Shipping, Ballast Water |
| 1992 | Neascus brevicaudatus | digenean fluke | Other Invertebrate | Eurasia | Lake Superior | Shipping, Ballast Water |
| 1992 | Trypanosoma acerinae | flagellate | Other Invertebrate | Ponto-Caspian | Lake Superior | Shipping, Ballast Water |
| 1992 | Dactylogyrus amphibothrium | monogenetic fluke | Other Invertebrate | Eurasia | Lake Superior | Shipping, Ballast Water |
| 1992 | Dactylogyrus hemiamphibothrium | monogenetic fluke | Other Invertebrate | Eurasia | Lake Superior | Shipping, Ballast Water |
| 1994 | Echinogammarus ischnus | amphipod | Benthic Crustacean | Ponto-Caspian | Detroit River/Lake Erie | Shipping, Ballast Water |
| 1994 | Scolex pleuronectis | cestode | Other Invertebrate | Ponto-Caspian | Lake St. Clair | Shipping, Ballast Water |
| 1994 | Neoergasilus japonicus | copepod | Zooplankton (crustacean) | Eastern Asia | St. Clair River | Unknown |
| 1994 | Megacyclops viridis | cyclopoid copepod | Zooplankton (crustacean) | Europe | Lake Huron | Unknown |
| 1994 | Sphaeromyxa sevastopoli | mixosporidian | Other Invertebrate | Ponto-Caspian | Lake St. Clair | Shipping, Ballast Water |
| 1995 | Alosa aestivalis | blueback herring | Fish | Atlantic NA | Lake Ontario | Canals |
| 1996 | Heteropsyllus nr. nunni | harpacticoid copepod | Benthic Crustacean | Atlantic NA? | Lake Michigan | Shipping, Ballast Water |
| 1997 | Acineta nitocrae | suctorian | Other Invertebrate | Eurasia | Lake Erie | Shipping, Ballast Water |
| 1998 | Cercopagis pengoi | fish-hook waterflea | Zooplankton (crustacean) | Ponto-Caspian | Lake Ontario | Shipping, Ballast Water |
| 1998 | Schizopera borutzkyi | harpacticoid copepod | Benthic Crustacean | Ponto-Caspian | Lake Michigan | Shipping, Ballast Water |
| 1999 | Nitocra incerta | harpacticoid copepod | Benthic Crustacean | Ponto-Caspian | Detroit River | Shipping, Ballast Water |
| 1999 | Daphnia lumholtzi | waterflea | Zooplankton (crustacean) | Africa, Australasia | Lake Erie | Release, unintentional |
| 2000 | Heterosporis sp. | microsporidian | Other Invertebrate | Unknown | Lake Ontario | Unknown |
| 2001 | Gammarus tigrinus | amphipod | Benthic Crustacean | Atlantic NA | L. Superior (L. Huron in 2002) | Shipping, Ballast Water |
| 2001 | Rhabdovirus carpio | SVC spring viraemia of carp | Virus | Eurasia | Lake Michigan drainage | Aquarium release |
| 2001 | Psammonobiotus communis | testate amoeba | Other Invertebrate | Ponto-Caspian | Lake Ontario | Shipping, Ballast Water |
| 2002 | Cylindrospermopsis raciborskii | cyanobacterium | Phytoplankton | South America? | Lake Michigan drainage | Unknown |
| 2002 | Ranavirus sp. | Largemouth Bass Virus | Virus | unknown | Lake Michigan drainage | Release, unintentional |
| 2002 | Piscirickettsia cf. salmonis | muskie pox | Other Invertebrate | unknown | Lake St. Clair | Unknown |
| 2002 | Psammonobiotus linearis | testate amoeba | Other Invertebrate | Ponto-Caspian | Lake Ontario | Shipping, Ballast Water |
| 2002 | Psammonobiotus dziwnowi | testate amoeba | Other Invertebrate | Ponto-Caspian? | Lake Ontario | Shipping, Ballast Water |
| 2003 | Enteromorpha flexuosa | green alga | Benthic Alga | Widespread | Lake Michigan drainage | Shipping |
| 2005 | Novirhabdovirus sp. | VHS | Virus | Atlantic NA? | Lake Ontario | Shipping? Ballast Water? |
| 2006 | Hemimysis anomala | bloody-red mysid | Benthic Crustacean | Ponto-Caspian | Lake Michigan drainage | Shipping, Ballast Water |
The total number of non-native species listed as being established (i.e. having a sustainable reproducing population) within the Great Lakes basin cannot be known with absolute precision, because of the following factors:
- It is highly likely that there have been invasions by other species that have not yet been detected.
- There are a number of species established in the Great Lakes whose origins are questionable. These species, termed cryptogenic, may have invaded centuries ago but their longterm presence in the basin causes them to be generally classified as native (many of these species are thought to have 'cosmopolitan' distributions). Similarly, some non-native species may have become established more recently, but are difficult to distinguish from native or other non-native species already present in the basin. This is especially likely for numerous invertebrate groups whose taxonomy is poorly known. In general, cryptogenic species are not included in this list.
- There have been a few non-native species found in the Great Lakes whose establishment is uncertain. Individuals have been introduced to the basin, perhaps multiple times, but may have failed to form sustainable populations. Alternatively, they may belong to small reproducing populations that have not yet been detected.
- Species native to one part of the basin (e.g., Lake Ontario) may be considered invasive to other portions of the basin. Species that are considered native to any portion of the Great Lakes are not included in this list.
*Ricciardi, A. Patterns of invasion in the Laurentian Great Lakes in relation to changes in vector activity. Diversity and Distributions (2006) 12, 425-433.