Species Profile

Silver Lamprey Great Lakes - Upper St. Lawrence populations

Scientific Name: Ichthyomyzon unicuspis
Other/Previous Names: Silver Lamprey (Great Lakes - Western St. Lawrence populations)
Taxonomy Group: Fishes
Range: Ontario, Quebec
Last COSEWIC Assessment: May 2011
Last COSEWIC Designation: Special Concern
SARA Status: No schedule, No Status

Individuals of this species may be protected under Schedule 1 under another name; for more information see Schedule 1, the A-Z Species List, or if applicable, the Related Species table below.

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Image of Silver Lamprey

Silver Lamprey Photo 1



The Silver Lamprey is one of eleven species of lamprey in Canada. There are two separately recognized populations of Silver Lamprey in Canada: i) the Great Lakes - Upper St. Lawrence populations; and ii) the Saskatchewan - Nelson River populations. The Silver Lamprey has the following characteristics: Jawless, eel-shaped fish with a sucking disc mouth and lack of paired fins; Seven pairs of gill openings; Newly metamorphosed juveniles may be as small as 9 centimeters; while spawning-sized adults range between 31 and 39 centimeters in length; Prior to spawning, adults exhibit a light yellow-tan colour on the ventral side (under side), that darkens into blue or blue-gray towards the dorsal side (back side); Larvae appear wormlike, and do not have eyes or teeth. Rather than a disc mouth, they have an oral hood; and, Lifespan ranges from six to eight years, with most of its life spent as larvae; adults die shortly after spawning.



Silver Lamprey are found in fresh waters in eastern North America, with a range extending from Manitoba to Tennessee in the west, and from Quebec and Vermont in the east. In Canada, it is separated into two populations: the Great Lakes and Upper St. Lawrence populations; and the Saskatchewan-Nelson River populations. Silver Lamprey from the Great Lakes and Upper St. Lawrence population have been documented in 41 streams and nine lakes including Lake Ontario, Lake Huron, Lake Superior, Lake Erie, Lake St. Clair, Lake Nipissing, Lake Champlain, Lac St. Pierre and Lac St. Louis. Silver Lamprey spawn in rivers and streams and require unrestricted migration to spawning habitat. Spawning habitat includes gravel and sand for building nests, clean fast-flowing water, and a small amount of silt-free sand or other materials on which the eggs can adhere. Spawning occurs only once in a lifetime and the adults die shortly afterward. Silver Lamprey eggs hatch after two to three weeks following fertilization and enter a larval stage. During this life stage, the worm-like larvae (called ammocoetes) drift downstream and burrow into soft sediments made of sand, silt and organic debris where they remain for four to seven years. At the end of this period, larvae undergo metamorphosis into their juvenile form, characterized by enlargement of the tail and dorsal fins, and development of eyes and a sucker disc lined with sharp teeth. The newly transformed juveniles migrate downstream into lakes or rivers in order to locate fish hosts on which to feed for one to two years before returning to streams to spawn.



Threats to the Silver Lamprey include methods used to control the invasive Sea Lamprey in the Great Lakes (for example. the application of lampricides and the construction of low head barriers to block spawning migrations), pollution, habitat alteration, dam construction, siltation, water fluctuations, and competition from other species. While most of these threats occur broadly across the Silver Lamprey’s range, Sea Lamprey control impacts are limited to Silver Lamprey nursery streams in the Great Lakes that receive lampricide treatments or have Sea Lamprey barriers. Lampricide treatments are not conducted in the Huron-Erie corridor or outside the Great Lakes Basin (such as Quebec and St. Lawrence River).



Federal Protection

Provincial and Territorial Protection

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.



PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.

5 record(s) found.

COSEWIC Status Reports

  • COSEWIC Assessment and Status Report on the Silver Lamprey, Great Lakes - Upper St. Lawrence populations and Saskatchewan - Nelson Rivers populations Ichthyomyzon unicuspis in Canada (2011)

    The Silver Lamprey (Ichthyomyzon unicuspis) is an eel-shaped fish that possesses a sucking disc mouth. Like all lampreys, it does not have jaws or paired fins, and has seven pairs of gill openings. The dentition pattern of adult lampreys is diagnostic to species, and the single dorsal fin helps distinguish Ichthyomyzon species from lamprey in other genera. Adult Silver Lamprey range in size from 9 to 39 cm in length. Before spawning, they have grey pigmentation that darkens toward the dorsal side, and are light yellow-tan on the ventral side. Lateral line organs are dark in larger individuals, but colourless in younger, smaller specimens. Larvae (“ammocoetes”) of Ichthyomyzon species are all very similar to each other morphologically. They appear almost worm-like, as they have no eyes or teeth. They possess an oral hood, rather than the sucking disc-like mouth of the adult form.

Response Statements

Action Plans

  • Multi-species Action Plan for Bruce Peninsula National Park and Fathom Five National Marine Park of Canada (2016)

    Bruce Peninsula National Park (BPNP) and Fathom Five National Marine Park (FFNMP) lie at the tip of the Bruce Peninsula which separates Georgian Bay from Lake Huron. The peninsula is 90 km in length and its most prominent feature is the Niagara Escarpment which runs along the entire eastern edge. Within BPNP, the escarpment forms the Georgian Bay shoreline and is recognized as part of the core area of the Niagara Escarpment UNESCO World Biosphere Reserve.  BPNP was established by the federal government in 1987 to protect a representative example of the Great Lakes/St. Lawrence Lowlands natural region. Because of the fragmented nature of the park properties, many of the stresses on the park’s ecosystem originate from outside its boundaries. For this reason, First Nations, local residents, non-governmental organizations, and other groups and land users play an important role in managing, restoring, and protecting the northern Bruce ecosystem. 

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2010 - 2011 (2011)

    Under Canada’s Species at Risk Act (SARA), the foremost function of COSEWIC is to “assess the status of each wildlife species considered by COSEWIC to be at risk and, as part of the assessment, identify existing and potential threats to the species”. COSEWIC held two Wildlife Species Assessment Meetings during the past year assessing the status or reviewing the classification of a total of 92 wildlife species.

Consultation Documents