Scientists discover new way to

trap, kill sea lamprey

A new way of trapping sea lamprey in the St. Mary’s River enabled scientists to kill more of the invasive species, which will bolster desirable fish populations in Lake Huron.


The sea lamprey is a non-native, eel-like fish that invaded the upper Great Lakes in the 1940s and decimated native fish populations. Sea lampreys attach to lake trout, whitefish and other desirable fish species and suck out bodily fluids. The Great Lakes Fishery Commission spends about $20 million annually to control sea lamprey populations all five Great Lakes.  In 2011-2012, scientists working for the commission developed new ways to trap sea lamprey in the St. Mary’s River, which links Lake Superior to Lake Huron. The St. Mary’s is home to the largest population of sea lamprey in the Great Lakes basin, with about 26,000 of the invaders. A project funded by the Great Lakes Restoration Initiative revealed that altering the flow of the St. Mary’s River through water level control structures enabled biologists to capture and kill about 400 additional sea lampreys each year. That number was significant because each female sea lamprey can produce between 30,000 and 100,000 eggs annually. Reducing the sea lamprey population bolsters populations of native and desirable fish species in Lake Huron.

Resource Challenges Addressed

  • Threat to native fish
  • Invasive species


Sea lampreys attach themselves to native fish, eventually killing them. Credit: National Oceanic and Atmospheric Administration Great Lakes Fish Laboratory.

Results and Accomplishments

Scientists captured and killed an additional 400 sea lamprey in the St. Mary’s River, which will prevent thousands of the invaders from attacking desirable fish in Lake Huron. The research findings, which revealed that lamprey traps work better in fast flowing water, will improve efforts to trap and kill sea lamprey in other Great Lakes tributaries.