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Great Lakes Aquatic Nonindigenous Species Information System


The Great Lakes have a long history of aquatic nonindigenous species (ANS) introductions – both intentional and unintentional. As of 2007, over 180 nonindigenous species have been reported to have reproducing populations in the Great Lakes basin, i.e. lakes Superior, Michigan, Huron, St. Clair, Erie, Ontario, and their connecting channels and water bodies within their respective drainages (Mills et al. 1993, Ricciardi 2001, Ricciardi 2006, Ricciardi unpubl. data). The two most recent ANS reported and verified established in the Great Lakes basin were viral hemorrhagic septicemia (VHS), and Hemimysis anomala.

The number of Great Lakes aquatic nonindigenous species documented in GLANSIS must be interpreted as a minimum. Identification depends on our ability to find, recognize, verify, and document new species, which is, in turn, dependent on our ability to adequately sample the Great Lakes ecosystem.

Species Included in GLANSIS

Species are assessed for inclusion in the database on a case-by-case basis. The present database targets ANS that are not considered to have been native to any part of the Great Lakes basin. Species that are documented as native to part of the basin, but invaded other parts of the basin due to human-expedited mechanisms or range expansions are not included in this database at the present time, except for the sea lamprey. Depending on availability of resources and expertise, we will likely modify this policy in the future. Some species are considered cryptogenic, meaning we currently do not know if their historic range included the Great Lakes, and as additional evidence is presented, such species may be added to or removed from GLANSIS.

Inclusion of the Sea Lamprey

The provenance of the sea lamprey in Lake Ontario is unresolved with Smith (1995) and Mandrak and Crossman (1992) arguing that it was non-native and Bailey and Smith (1981), Daniels (2001), and Bryan et al. (2005), among others, arguing that it was native. Regardless of its status in Lake Ontario, virtually all agree that it subsequently spread to the rest of the Great Lakes after the opening of the Welland Canal. We include it in this database because of its historic and present importance as an invader in most of the Basin and its devastating basin-wide impact on Great Lakes fisheries.

Database Structure

GLANSIS functions as a Great Lakes specific node of the USGS NAS national database. Information entered for GLANSIS automatically appears in N AS. GLANSIS provides targeted access to the information – especially collection records – for established Great Lakes nonindigenous species in the NAS Database. Our goal is to eventually complete profiles for all Great Lakes nonindigenous species that meet our criteria for listing (below).

Additional information on aquatic invasive species related to the Great Lakes region that are not included in GLANSIS – e.g., species which have been reported but not established, failed introductions, cryptogenic species for which evidence is considered insufficient (such as Gammarus fasciatus), range expansions, and species native to the Great Lakes which have invaded other regions of the U.S. may be available through USGS NAS.

GLANSIS Definitions and Criteria for Listing

Based on these criteria, the list of aquatic nonindigenous species found via GLANSIS is subject to constant revision.

Geographic criterion: Only species which are established in the Great Lakes basin below the ordinary high water mark -- including connecting channels, wetlands and waters ordinarily attached to the Lakes -- are included in the GLANSIS database. Species which have invaded inland lakes within the Great Lakes basin but not meeting the above geographic criterion are not included in the database.

Aquatic criterion: GLANSIS includes only aquatic species. USDA wetland indicator status is used as a guideline for determining whether wetland plants should be included in the list - OBL, FACW and FAC wetland plants are included in this list as aquatic; FACU and UPL plants are not. In keeping with this criteria, the following upland, facultative upland and terrestrial plants were removed from the list (12/08): Lotus corniculatus, Sonchus arvensis, Sonchus arvensis var. glabrescens, Carex flacca, Epilobium parviflorum, Polygonum caespitosum var. longisetum. Waterfowl, reptiles and mammals spending significant time in and dependent on the water are not currently included, but are being considered for addition to the database.

Nonindigenous criterion: The species included in GLANSIS are those which are considered nonindigenous within the Great Lakes basin according to the following definitions and criteria (based on Ricciardi 2006):

  1. the species appeared suddenly and had not been recorded in the basin previously;
  2. it subsequently spreads within the basin;
  3. its distribution in the basin is restricted compared with native species;
  4. its global distribution is anomalously disjunct (i.e. contains widely scattered and isolated populations);
  5. its global distribution is associated with human vectors of dispersal;
  6. the basin is isolated from regions possessing the most genetically and morphologically similar species.

Cryptogenic species are those species that cannot be verified as either native or introduced (after Carlton, 1996). These include species that may have been identified as invasive by one researcher, but for which a literature review reveals conflicting opinions. For example, Paranais frici and Pritina acuminata, listed as invasive by Trebitz et al 2009, are not considered so by others (Spencer & Hudson 2003, Moroz 1994).

Species that have been identified as cryptogenic are generally not listed, but are being considered for inclusion in a separate list or in the main GLANSIS list with an appropriate identifier.

Species which have expanded their ranges within the basin (e.g., those native to Lake Ontario which have invaded Lake Superior) are not systematically included in the main GLANSIS list but are being considered for inclusion in a separate list or in the main GLANSIS list with an appropriate identifier. The only species presently included in GLANSIS that violates the criterion of no previous evolutionary history in the Great Lakes basin is the sea lamprey.

Note: Although widely used, the term 'invasive' is vague and subject to widely inconsistent usage. Biologically it is often related to the relative ability of a species to spread and establish in new areas, while legislatively and politically it is used to characterize a nonindigenous species “whose introduction does or is likely to cause economic or environmental harm or harm to human health” (Executive Order 13112, February 1999). Thus, the term 'invasive' has multiple meanings and requires a subjective judgment. We avoid using the term 'invasive', but may use the word 'invader', in the context that a nonindigenous species that has successfully established a reproducing population is an 'invader'. 'Exotic' is a commonly used synonym for 'nonindigenous'.

Established criterion: A nonindigenous species is considered established if it has a reproducing population within the basin, as inferred from multiple discoveries of adult and juvenile life stages over at least two consecutive years. Given that successful establishment may require multiple introductions, species are excluded if their records of discoveries are based on only one or a few non-reproducing individuals whose occurrence may reflect merely transient species or unsuccessful invasions.

Thus common carp, which were first collected in the Great Lakes in 1880, is included in the database. Grass carp, which is not believed to be reproducing in the Great Lakes (and so not established) is not included. While bighead and silver carp eDNA has recently (2009) been reported in southern Lake Michigan, presence of adult reproducing fish has not been verified, so these species are not included in GLANSIS either.


Trebitz, A.S. et al. 2009. Exploiting habitat and gear patterns for efficient detection of rare and non-native benthos and fish in Great Lakes coastal ecosystems. Aquatic Invasions (2009) Volume 4, Issue 4: 651-667.

Ricciardi A. 2006. Patterns of invasion in the Laurentian Great Lakes in relation to changes in vector activity. Divers. Distrib. 12, 425–433.

Bryan, M.B, D. Zalinski, B. Filcek, S. Libants, W. Li, and K.T. Scribner. 2005. Patterns of invasion and colonization of the sea lamprey. Molecular Ecology 14:3757–3773

Spencer, D. R. and P. L. Hudson. 2003. The Oligochaeta (Annelida, Clitellata) of the St. Lawrence Great Lakes region: an update. Journal of Great Lakes Research 29: 89-104

Daniels, R. A. 2001. Untested assumptions: the role of canals in the dispersal of sea lamprey, alewife, and other fishes in the eastern United States. Env. Biol. of Fishes. vol:60 pgs:309-329

Ricciardi A. 2001. Facilitative interactions among aquatic invaders: is an “invasional meltdown” occurring in the Great Lakes? Can. J. Fish. Aquat. Sci. 58: 2513-2525.

Carlton J.T. 1996. Biological invasions and cryptogenic species. Ecology 77:1653-55

Smith, S. H. 1995. Early changes in the fish community of Lake Ontario. Great Lakes Fishery Commission Technical Report 60, Ann Arbor.

Moroz, T.G. 1994 Aquatic Oligochaeta of the Dnieper-Bug Estuary system. Hydrobiologia 278: 133-138

Mills EL, Leach JH, Carlton JT, Secor CL. 1993. Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions. J. Great Lakes Res. 19: 1–54.

Mandrak, N. E., and E. J. Crossman. 1992. Postglacial dispersal of freshwater fishes into Ontario. Canadian Journal of Zoology 70:2247-2259.

Bailey, R.M., and G.R. Smith. 1981. Origin and geography of the fish fauna of the Laurentian Great Lakes basin.Canadian Journal of Fisheries and Aquatic Sciences. National Research Council Canada vol:38 iss:12 pgs:1539-1561

Smith, B. R., and J. J. Tibbles. 1980. Sea lamprey (Petromyzon marinus) in Lakes Huron, Michigan, and Superior: history of invasion and control, 1936-78. Canadian Journal of Fisheries and Aquatic Sciences 37(11):1780-1801.

Lawrie, A. H. 1970. The sea lamprey in the Great Lakes. Transactions of the American Fisheries Society 99:766-775.


Support for this project has been provided by the NOAA Invasive Species Program (Silver Spring, MD), the NOAA Great Lakes Environmental Research Laboratory (Ann Arbor, MI) and the Great Lakes Fishery Trust (Lansing, MI). The GLANSIS project has received 2010 funding from USEPA under the Great Lakes Restoration Initiative (GLRI) for serveral improvements.

See Also:

GLANSIS Poster (.pdf)