The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Anguilla sp.
Anguilla sp.
(unidentified eel)

Copyright Info
Anguilla sp. Schrank, 1798

Common name: unidentified eel

Taxonomy: available through www.itis.govITIS logo

Identification: Genus is currently recognized as containing 15 species. McCosker (1989) provides a key to the five Anguilla species most likely to have been imported.

Size: To over 200 cm.

Native Range: Marine, estuarine, and fresh water. Most temperate and tropical regions of the world (Berra 1981; Nelson 1994).

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Anguilla sp. are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CA187719843California Region; San Francisco Coastal South; San Joaquin Delta
OR198119911Lower Willamette

Table last updated 7/24/2024

† Populations may not be currently present.

Means of Introduction: These eels were probably imported by Japanese or Chinese restaurants, or by fish farms, and the eels either escaped or were released (Williamson and Tabeta 1991; Moyle 2002).

Status: Reported from, but failed in, California, Nevada, and Oregon.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: There is some confusion concerning the correct identity of the eel taken from the San Joaquin River, California. The voucher specimen (SIO 64-219) is a skin only; it was reported as A. rostrata by Skinner (1971) and as being either A. rostrata or A. anguilla by McCosker (1989) (see species account for A. rostrata). One of the three Oregon specimens was reported as being kept alive in an aquarium (as of 1990); the other two specimens were not preserved (Williamson and Tabeta 1991).

References: (click for full references)

Berra, T. M. 1981. An atlas of distribution of the freshwater fish families of the world. University of Nebraska Press, Lincoln, NE.

Deacon, J. E., and J. E. Williams. 1984. Annotated list of the fishes of Nevada. Proceedings of the Biological Society of Washington 97(1):103-118.

McCosker, J. E. 1989. Freshwater eels (family Anguillidae) in California: current conditions and future scenarios. California Fish and Game 75(1):4-10.

Minckley, W. L. 1973. Fishes of Arizona. Arizona Fish and Game Department. Sims Printing Company, Inc., Phoenix, AZ.

Moyle, P.B. 2002. Inland Fishes of California. Second Edition. University of California Press, Berkeley, CA. 502 pp.

Nelson, J. S. 1994. Fishes of the world, 3rd edition. John Wiley and Sons, New York, NY.

Skinner, J. E. 1971. Anguilla recorded from California. California Fish and Game 57(1):76-79.

Williamson, G. R., and O. Tabeta. 1991. Search for Anguilla eels on the West Coast of North America and on the Aleutian and Hawaiian Islands. Japanese Journal of Ichthyology 38(3):315-317.

Other Resources:
FishBase Summary

Author: Leo Nico, and Pam Fuller

Revision Date: 5/9/2019

Peer Review Date: 3/5/2011

Citation Information:
Leo Nico, and Pam Fuller, 2024, Anguilla sp. Schrank, 1798: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=311, Revision Date: 5/9/2019, Peer Review Date: 3/5/2011, Access Date: 7/24/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [7/24/2024].

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