Sea Lamprey

Scientific Name: Petromyzon marinus


Lee Emery, U.S. Fish and Wildlife ServiceCopyright Info


U.S. Fish and Wildlife ServiceCopyright Info

Identification: The sea lamprey is a fish that is eel-like in appearance. It has a skeleton made of cartilage and lacks a jaw. This species has seven gill openings, two fins along its backs, and no side fins. The sea lamprey has a large, round mouth with sharp, curved teeth. It is a parasitic feeder that attaches to the surface of other fish to consume fluids and tissues. After a meal, it detaches and swims away.


Size: Ocean-dwelling sea lamprey can grow up to 47 inches (120 cm) in length. Freshwater sea lamprey can grow up to 25 inches (64 cm) in length.


Native Range: The sea lamprey generally lives in saltwater but swims up freshwater rivers to reproduce. It can be found along the Atlantic Coast from Labrador to Florida and in the Gulf of Mexico. It has also been observed along the Atlantic Coast of Europe and the Mediterranean Sea. Some populations have become landlocked in the Great Lakes and several New York lakes and these sea lamprey spend their entire lives in freshwater.


Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, 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 Petromyzon marinus are found here.

Full list of USGS occurrences

State/ProvinceYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Illinois193619851Lake Michigan
Indiana194920053Lake Michigan; Little Calumet-Galien; St. Joseph
Michigan1934201630Au Gres-Rifle; Bad-Montreal; Betsie-Platte; Betsy-Chocolay; Black-Macatawa; Black-Presque Isle; Boardman-Charlevoix; Brevoort-Millecoquins; Carp-Pine; Dead-Kelsey; Fishdam-Sturgeon; Keweenaw Peninsula; Lake Huron; Lake Michigan; Lake St. Clair; Lake Superior; Little Calumet-Galien; Lone Lake-Ocqueoc; Manistee; Maple; Menominee; Muskegon; Ontonagon; Pere Marquette-White; St. Clair; St. Joseph; St. Marys; Tacoosh-Whitefish; Thunder Bay; Waiska
Minnesota194620012Beartrap-Nemadji; Lake Superior
New York1863201418Ausable River; Black; Buffalo-Eighteenmile; Cattaraugus; Grass; Irondequoit-Ninemile; Lake Champlain; Lake Erie; Lake Ontario; Mettawee River; Niagara; Oneida; Raisin River-St. Lawrence River; Raquette; Salmon; Salmon-Sandy; Seneca; St. Regis
Ohio194720104Ashtabula-Chagrin; Chautauqua-Conneaut; Grand; Lake Erie
Ontario20102010*
Pennsylvania198520002Chautauqua-Conneaut; Lake Erie
Wisconsin195820118Bad-Montreal; Beartrap-Nemadji; Door-Kewaunee; Lake Michigan; Lake Superior; Lower Fox; Manitowoc-Sheboygan; Oconto

Table last updated 9/30/2019

† Populations may not be currently present.

* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).


Means of Introduction: There is controversy concerning whether the sea lamprey is native to Lake Ontario. Those who say it is not native to the lake believe this species, unknown in Lake Ontario prior to the 1830s, most likely entered through the artificially created Erie Canal. Regardless, it is certain that the species is not native to the other Great Lakes or their connecting rivers and streams where sea lamprey are now present. The sea lamprey was originally prevented from spreading into Lake Erie and the rest of the Great Lakes Basin by Niagara Falls. The Welland Canal, opened in 1829, bypassed Niagara Falls and provided a route to Lake Erie from Lake Ontario. Sea lamprey were found in the farthest Great Lake, Lake Superior, within 25 years of their arrival in Lake Erie.


Status: Sea lamprey was first discovered in Lake Ontario in 1835, Lake Erie in 1921, Lake Michigan in 1936, Lake Huron in 1937, and Lake Superior in 1946. In addition to populating all the Great Lakes, sea lamprey can be found in some connecting rivers or streams in New York, Pennsylvania, Ohio, Michigan, Illinois, Indiana, Minnesota, and Wisconsin.


Remarks: Early methods to control this species included mechanical dams and electrical barriers. Beginning in the late 1950s, sea lamprey have been successfully controlled by the use of lampricide, a chemical agent that kills larval lamprey in their stream habitats. The lampricide has reduced the population by more than 90 percent of the 1961 peak. As a result, the sea lamprey’s impact on native fishes has been reduced and commercial fisheries reportedly have shown some recovery. The continued use of lampricide is sometimes harmful to other fish and to the larvae of nonparasitic lamprey species. However, according to the Great Lakes Fishery Commission, the impact to these non-target organisms is considered minimal when lampricide treatments are performed properly.

As of 1991, it was estimated the United States and Canada were spending $8 million per year on lamprey control and another $12 million per year on lake trout restoration.


Other Resources:
GLANSIS Technical Species Profile

Sea Lamprey Fact Sheet (Great Lakes Fishery Commission)

Sea Lamprey (Great Lakes Science Center)

Sea Lamprey (WI DNR Critter Corner)

Sea Lamprey: The Battle Continues (MN Sea Grant)



Author: Illinois-Indiana Sea Grant


Contributing Agencies:
NOAA Sea Grant GLRI Logo


Revision Date: 4/24/2012


Citation for this information:
Illinois-Indiana Sea Grant, 2019, Sea Lamprey: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatLakes/FactSheet.aspx?SpeciesID=836&Potential=N&Type=1&HUCNumber=, Revision Date: 4/24/2012, Access Date: 10/13/2019

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.