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 (NOAA) 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 them 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, gizzard shad, and 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 published in the journal Transactions of the American Fisheries Society. That in turn would hurt walleye, a commercially valuable species that eat the smaller fish.
Two Asian carp species found in the United States, the big head carp and 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 cat fish farms in some ponds in Arkansas,” said Ed Rutherford, co-author 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 of all the fish by weight in those rivers he said, but 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.
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Original article from TakePart