Scientific name: Ichthyomyzon unicuspis
Special concern (Great Lakes - Upper St. Lawrence River population)
"Special concern" means the species lives in the wild in Ontario, is not endangered or threatened, but may become threatened or endangered due to a combination of biological characteristics and identified threats.
Date added to the Species at Risk in Ontario List
January 24, 2013
Read the Assessment Report
What it looks like
The silver lamprey is an eel-shaped fish with a sucking disc mouth. Like all lampreys, it does not have jaws or paired fins. Adult silver lampreys range from nine to 39 centimetres long. Young lampreys have yellow to tan/grey backs, becoming darker as adults, with a light blue-grey to silver belly.
Silver lampreys are very difficult to correctly identify. Experts must rely on differences in fin shapes and teeth arrangements to distinguish between them and other lamprey species.
Adult silver lampreys are parasites. They attach themselves to different host fish species, feeding on flesh and body fluids. They live for 12 to 20 months as parasites before migrating up streams to spawn, then die after spawning.
Where it lives
Silver lampreys require clear water so they can find fish hosts, relatively clean stream beds of sand and organic debris for larvae to live in, and unrestricted migration routes for spawning.
Their use of different kinds of habitat throughout their lives (rivers for spawning and early development, and lakes for adults) makes them vulnerable to changes in their environment.
Where it’s been found in Ontario
Outside Ontario, the silver lamprey is found in tributaries that feed the St. Lawrence River in Quebec and New York west through to Manitoba and tributaries of the Nelson River. Silvery lampreys are also found in the upper Mississippi River tributaries.
What threatens it
The Great Lakes - Upper St. Lawrence River population of silver lamprey is of Special Concern due to a variety of threats, including habitat loss and the use of lampricides – chemicals designed to kill lampreys used to control the invasive sea lamprey.
Dams that restrict the lamprey’s ability to migrate from lakes to breeding areas in streams pose a threat, along with chemical pollution, especially the widely used herbicide Atrazine.
What you can do
Report a Sighting
- Report a sighting of an endangered animal or plant to the Natural Heritage Information Centre. Photographs with specific locations or mapping coordinates are always helpful.
Be a good steward
- private land owners have a very important role to play in species recovery; if you find silver lamprey on your land, you may be eligible for stewardship programs that support the protection and recovery of species at risk and their habitats
- invasive species seriously threaten many of Ontario’s species at risk; to learn what you can do to help reduce the threat of invasive species, visit:
Report illegal activity
Report any illegal activity related to plants and wildlife to
- silver lampreys belong to the most ancestral lineage of vertebrates (animals with backbones); from them we may be able to learn about evolutionary pathways, such as the transition from jawless to jawed vertebrates
- lamprey larvae have been used as bio-monitors to measure the health of the streams where they live; by monitoring the larvae, researchers can identify changes in population sizes and potential problems within their ecosystems
- silver lamprey are one of five species of lamprey in Ontario whose larvae all look identical, making it difficult to distinguish juveniles of the species