Lamprey Effects On Great Lakes And Smallmouth Bass

There are numerous types of lampreys in the United States, many of which are native to our waterways.  The biggest concern that people have with regards to lampreys are their effects on the game fish of the Great Lakes such as lake trout, salmon and smallmouth bass.

On the website of the Pennsylvania fish and boat commission alone, there are 5 different types of lamprey listed as native species.  The Ohio lamprey and the Sea Lamprey are parasitic fish that use their cutting tongue and mouth to make a hole in the side of the fish they are attacking and then feed off the bodily fluids as a parasite.

In Pennsylvania, the sea lamprey (Petromyzon marinus) naturally runs up the Delaware River from the Atlantic Ocean to spawn. It is also present in Lake Erie and the other Great Lakes. Sea lampreys bypassed the barrier of Niagara Falls after the Welland Canal was built. By the 1920s, they had spread all the way to the upper Great Lakes. Thus, although natives of the Delaware watershed, they are non-native to the Great Lakes and Lake Erie. Sea lampreys feed by attaching themselves by their concave, round, suctiondisk mouth to the exterior of fish. They rasp a hole in the skin with their rough tongue, and feed on the host fish’s body fluids. They may kill their host directly, or weaken it so much that fungus infections and other ills destroy it. The sea lamprey invasion of the Great Lakes caused disastrous declines in lake trout and whitefish populations, affecting commercial and sport fisheries. Great Lakes tributary streams where sea lampreys spawn are treated with a chemical to reduce this damaging parasite’s numbers. Sea lampreys have little effect on native fishes in the Delaware River because the adult parasitic form inhabits the Atlantic Ocean.

The sea lamprey is the one that has devastated lake trout populations in the Great Lakes and are known to attack and kill salmon, walleye and smallmouth bass as well.   These are not native to the Great Lakes and the Great Lakes Fish Commission has been battling the sea lamprey since 1955.  Source

Life cycle of the sea lamprey

The lamprey has had a tremendous effect on the Great Lakes.

Sea lampreys are considered a pest in the Great Lakes region. The species is native to the inland Finger Lakes and Lake Champlain in New York and Vermont. It is not clear whether it is native to Lake Ontario, where it was first noticed in the 1830s, or whether it was introduced through the Erie Canal which opened in 1825.  Improvements to the Welland Canal in 1919 are thought to have allowed its spread from Lake Ontario to Lake Erie, and while it was never abundant in either lake, it soon spread to Lake Michigan, Lake Huron, and Lake Superior, where it decimated indigenous fish populations in the 1930s and 1940s. They have created a problem with their aggressive parasitism on key predator species and game fish, such as lake trout, lake whitefish, chub, and lake herring. Elimination of these predators allowed the alewife, another invasive species, to explode in population, having adverse effects on many native fish species. The lake trout plays a vital role in the Lake Superior ecosystem. The lake trout is considered an apex predator, which means the entire system relies on its presence to be diverse and healthy. With the removal of an apex predator from a system, the entire system is affected. The sea lamprey is an aggressive predator by nature, which gives it a competitive advantage in a lake system where it has no predators and its prey lacks defenses against it. The sea lamprey played a large role in the destruction of the Lake Superior lake trout population. Lamprey introduction along with poor, unsustainable fishing practices caused the lake trout populations to decline drastically. The relationship between predators and prey in the Great Lakes’ ecosystem then became unbalanced.  Source

This is an example of how some invasive species can devastate a native population.  It is interesting that these predators are harmless to the fresh water species in the Delaware River because they return to the Atlantic ocean for their adult life and to find a host to feed off of.  However, in the Great Lakes, Sea Lamprey move from rivers and streams into the closed population of the lakes and wreak havoc on other native species.

Let’s hope these nasty parasites can be eradicated or severely reduced through increased knowledge and technology.

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