Barrier Will Help Reduce

the Sea Lamprey Population

A barrier installed in northern Indiana’s Trail Creek will reduce the number of sea lamprey in Lake Michigan, where the blood-sucking invaders prey on fish.


The sea lamprey is an eel-like, parasitic fish that snuck into the Great Lakes between 1825 and 1930 through manmade canals. The invaders wiped out much of the lake trout population in the Great Lakes by the late 1940s. Since 1954, the Great Lakes Fishery Commission has been controlling sea lamprey populations with chemicals, barriers and the release of sterile male lampreys. Those efforts have reduced the sea lamprey population by 90 percent in most areas of the lakes, but the battle to keep the monstrous invaders in check will continue indefinitely. The barrier in Trail Creek, a tributary of Lake Michigan, will reduce the sea lamprey population by blocking access to spawning habitat. Desirable fish species will be able to leap over or bypass the sea lamprey barrier.

Resource Challenges Addressed

  • Threat to native fish populations
  • Invasive species

Results and Accomplishments

The barrier will prevent tens of thousands of sea lamprey — each of which consumes up to 40 pounds of fish — from spawning in Trail Creek and feeding in Lake Michigan. The barrier also eliminates the need for chemical treatments of Trail Creek, which will free up financial resources that fishery managers can use to fight sea lamprey elsewhere in other Great Lakes tributaries.


Sea lamprey show off their rows and rows of teeth.

The barrier on Trail Creek will keep thousands of sea lamprey (above) from killing Lake Michigan fish. Each lamprey consumes up to 40 pounds of fish during its time in the lake. Lamprey attach to fish and suck their blood and other bodily fluids. Photo credit: Dave Brenner, Michigan Sea Grant.