The Asian Carp Invasion Could Empty Lake Erie of Fish
Lake Erie is bountiful in highly prized walleye and rainbow trout. But populations of these commercially important fish could plummet if Asian carp manage to invade the lake, according to a new report.
In the first-of-its-kind study, scientists from the National Oceanic and Atmospheric Administration and the University of Notre Dame found that carp, which are moving at a rapid clip toward the Great Lakes, could make up a third of all fish in Lake Erie by weight within 20 years if the invasive species overcomes efforts to keep it at bay.
Voracious eaters, Asian carp feed on plankton, tiny organisms which form the basis of the food web. Small fish that live in Lake Erie—such as the emerald shiner, the gizzard shad, and the rainbow smelt—also feed on plankton, and their numbers could fall dramatically if they have to compete with carp for food, according to the study, which was published in the journal Transactions of the American Fisheries Society. That in turn would hurt the commercially valuable walleye, which eat the smaller fish.
Two Asian carp species found in the United States, the bighead carp and the silver carp, have reached watersheds near the Great Lakes. In October, U.S. Fish and Wildlife Service scientists discovered that silver carp had advanced a record 12 miles up the Illinois River in just one month, traveling 66 miles toward Lake Michigan since the beginning of 2015.
“Back in the 1970s, the carp were introduced purposely to clear out catfish farms in some ponds in Arkansas,” said Ed Rutherford, coauthor of the study and a fisheries biologist with the NOAA Great Lakes Environmental Research Laboratory. “They escaped from there during some flooding and made their way into the watershed of the Mississippi and are now very abundant in the Mississippi and the Illinois rivers.”
The carp now make up about 80 percent, by weight, of all the fish in those rivers, he said, but a computer modeling study shows that the potential impact on Lake Erie would not be as extreme.
“That’s because Lake Erie has more potential predators for young Asian carp than in those rivers,” Rutherford said.