The Invasive Sea Lamprey Affects Lake Michigan Fishing

When not on the field, Wabash College lacrosse coach Terry Corcoran spends time with his sons boating and fishing on Lake Michigan. Beautiful and scenic, Lake Michigan is the third largest of the Great Lakes and the sixth largest lake in the world. It covers 22,300 square miles, offering Terry Corcoran and fellow outdoors enthusiasts excellent fishing for trout, salmon, walleye, and smallmouth bass. Unfortunately, over the last century, an invasive species called the sea lamprey has had a negative impact on the fisheries of Lake Michigan.

The sea lamprey is a parasitic animal that is native to the Atlantic Ocean. It has a suction cup mouth ringed with razor sharp teeth. Lampreys attach to native fish and then feed on the fish’s blood and bodily fluids, usually resulting in the death of the fish. Over the last century, native fish populations have dramatically suffered from the parasitic animal. Once populous fisheries experienced dramatic reductions, sometimes up to 85 percent. Some of these fisheries have recovered, but the impact of the lamprey is still seen in the Great Lakes.

Prior to 1800, the sea lamprey was kept out of the Great Lakes by the natural barrier created by the Niagara Falls. After modernization updates were completed on the Welland Canal in 1919, the species was noticed in Lake Erie. Not long after entering Lake Erie, the lamprey quickly spread through shipping channels and modern locks to the other Great Lakes, wreaking havoc on native fisheries along the way.

Sea lampreys are known to breed in 433 of the 5,747 tributary streams emptying into Lake Michigan. The Great Lakes Fishery Commission currently treats 250 of those streams on a rotating basis, about 60–70 per year.