Beneath the surfaces of North America’s rivers, fish are fighting a war. For over 100 years, sea lampreys (Petromyzon marinus) have been ambushing and killing fish in the Great Lakes.
Lampreys are 30 to 76 cm long with no scales. Their skin is leathery with dark blotches and a lighter belly.
They have large eyes, two dorsal fins and seven obvious gill openings on each side.
[Photo credit: Flickr Creative Commons – Dave Throup]
On Friday July 17, Ted Lawrence from for the Great Lakes Fishery Commission (GLFC) visited Credit Valley Conservation and gave an interactive presentation on sea lampreys.
Ted showing the audience how sea lamprey have seven gills on each side of their bodies.
Ted began with a quick history lesson. In the late 1830’s, sea lampreys, which are native to the Atlantic Ocean, swam up the St. Lawrence Seaway shipping canal system. In 1919, lampreys entered the upper Great Lakes via the Welland Shipping Canal, which bypasses Niagara Falls. From there, the sea lampreys swam into the rest of the Great Lakes. Since invading the Great Lakes, lampreys have adapted from their salt water environment and can now live entirely in fresh water.
Using their large, suction-cup mouth, horn-shaped teeth and razor sharp tongue, lampreys latch onto any fish – literally sucking the like out of them. Their toonie sized mouths have 60 lbs of suction per square inch. That’s like getting attacked by a vacuum cleaner with teeth!
At the centre of a lamprey’s sucker is a thrashing razor sharp tongue that tears into the flesh of its prey.
Lamprey’s feast on their prey’s blood and other internal fluids.
[Photo credit: Photo from US EPA]
These small, snake-like creatures have a negative impact on Great Lake habitats. Did you know that one sea lamprey can kill up to 40 lbs of fish? Uncontrolled, these creatures are capable of wiping out entire fish populations. In the 1960’s, sea lampreys killed off almost all lake trout in the Great Lakes.
Adult lampreys spawn in rivers and streams. The rocky conditions are ideal for lamprey larvae. They are similar to salmon in that they swim upstream to spawn and then die. Lampreys can survive for as long as 10 years, but are parasitic for only 12 – 18 months, doing all their during that time.
In southern Ontario, a steelhead trout was found dead with sea lamprey wounds.
[Photo credit: Flickr Creative Commons – USFWSmidwest]
Native fish species need help in the fight against sea lamprey. The GLFC uses a number of techniques to reduce lamprey populations. Lampricide is the most effective method. It’s a liquid treatment that kills lamprey larvae and is not toxic to fish. Other techniques include the use of dams and new techniques like the use of pheromones. The GLFC has reduced sea lamprey populations in the Great Lakes by about 95 per cent.Scientists are constantly looking for new ways to manage sea lamprey.
At the end of the session, one CVC staff member asked about a recent discovery in human salvia being used as lampricide. Ted explained how although human saliva has a specific element that repels lampreys, scientists have yet to discover a successful way of collecting the chemical found in saliva. In the video below, Mike Rowe, host of Discovery Channel’s Dirty Jobs, learns how sea lampreys react to human saliva.
Near the end of the presentation, Ted asked if anyone was interested in having a lamprey suctioned to their hand. Within seconds, hands from the audience shot up in every direction.
Ted took the lampreys out of their tank and placed their mouths on the audience members’ palms.
Check out how the Great Lakes Fishery Commission continues to search for new ways to control sea lamprey populations. CVC is committed to protecting all native and at-risk fish species. Check out our Invasive Species Program to learn more.
Article by CVC’s Kimberley Holt-Behrend