A new study shows that the population of sport fish — including bluegill, crappie and yellow perch — has dropped significantly in parts of the Upper Mississippi River that now are home to large numbers of Asian carp. That’s bad news for the Great Lakes fishery, where many fear Asian carp soon may appear.
Most of us who enjoy fishing begin by angling for panfish, species that rarely grow larger than a frying pan. They can be relatively easy to catch, they offer a spirited fight and they taste delicious. They’re an ideal introduction to fishing. But children a generation or two in the future may find panfish a rare commodity.
The Upper Mississippi River study shows that where Asian carp move in, other fish species fade away. Asian carp, particularly the Bighead and silver varieties, eat plankton — the same food nearly all young fish depend on.
This is far from the first time an invasive species has threatened the Great Lakes. Mankind long has fiddled with the biological mix in the Great Lakes. We over-fished the Arctic Grayling until it became extinct in Michigan waters. We over-fished the sturgeon until it’s population in Michigan waters now is holding at only 1 percent what it was in the mid-1800s. We accidentally introduced invasive species like round goby and zebra mussels. We purposely introduced non-native species like Pacific salmon.
Michigan Sea Grant, a cooperative program of the University of Michigan, Michigan State University, and the National Oceanic and Atmospheric Administration, says that since the 1800s an estimated 187 non-native species have become established in the Great Lakes.
Only the real nasty ones get much attention.
The awful-looking teeth of the sea lamprey — which latch onto other fish and drink their blood, usually resulting in death for the host fish — captured headlines when that species swam into Lake Michigan and Lake Huron in the 1930s.
Before the lamprey invasion, according to the Great Lakes Fishery Commission, the U.S. and Canada each year harvested about 15 million pounds of lake trout in the upper Great Lakes. Sea lamprey populations exploded in the 1940s. They fed on lake trout, lake whitefish and ciscoes, all fish that were mainstays of the fishery. By the early 1960s, the catch had dropped to only about 300,000 pounds — a mere 2 percent of the previous average. Hundreds of thousands of jobs related to the fishery industry were lost, the commission says. Lamprey control efforts still are in progress.
An Asian carp invasion could have just as devastating an effect on the fishery.
Instead of killing adult fish like the lamprey, Asian carp gobble up the plankton food source that otherwise would feed young fish of sport fish species. That’s apparently what has happened in the Mississippi River.
The U.S. Army Corps of Engineers has been monitoring fish in the river system for more than 20 years, including several years before the carp arrived. Analyzing Corps numbers compiled between 1994 and 2013, a research team found that the number of sport fish dropped about 30 percent in two carp-infested areas on the Mississippi River and one on the Illinois River. Sport fish numbers during the same period grew nearly 35 percent in three sections of the Mississippi farther upstream where the carp hadn’t reached.
Today’s sport fishers worry that similar changes in fish populations could occur if Asian carp become established in the Great Lakes. Tomorrow’s sport fishers worry even more.
A coalition of many government agencies from the U.S. and Canada got together as the Asian Carp Regional Coordinating Committee and in March published the 2019 Asian Carp Action Plan. The 270-page document, viewable at https://www.asiancarp.us/Documents/2019Action Plan.pdf, details a long list of participants, action items and deadlines.
The plan’s last page deals with just one of the many plan facets, but includes a line that well describes the Asian carp saga: “Expected Completion Date for Project: Unknown.”