Predicted Asian Carp Impacts For Lake Erie Fish

By on January 6, 2016
Two silver carp pulled from the Mississippi River in Missouri. (Credit: Sara Tripp / Missouri Department of Conservation)

What could happen to some of your favorite game fish if invasive Asian carp make it into Lake Erie?

The question has been troubling anglers, in addition to fisheries researchers, for some time. But a new study led by scientists at the University of Michigan forecasts a mixed bag of effects, though still an overall negative impact.

Most of the fish species in the lake, including its prized walleye, would see declines, scientists found. But other fish, including smallmouth bass, would probably see population increases. The winner, of course, would still be Asian carp, as the invasive fish would likely come to take up about a third of the total fish weight in Lake Erie.

The investigation used a food-web model to determine the probable impacts of Asian carp — specifically bighead and silver carp — invasion in Lake Erie. But unlike other studies into the issue, scientists incorporated expert opinions to account for uncertainty.

Using that approach, researchers found that the invasion of Asian carp into Lake Erie would most likely affect its food web in two ways. For one, the invasive fish would likely compete with native fish by eating their prey, while, for another, juvenile Asian carp would probably become food for fish that prey on other fish.

So what does this mean for Lake Erie’s world-class fishery?

Walleye, rainbow trout, gizzard shad and emerald shiners could all decline, with those for shiners predicted at 37 percent. Smallmouth bass, on the other hand, were predicted to gain in population by about 16 percent.

A Lake Erie food web modified to consider the effects of Asian carp invasion. (Credit: University of Michigan)

A Lake Erie food web modified to consider the effects of Asian carp invasion. (Credit: University of Michigan)

Results of the modeling suggest that Asian carp could eventually account for up to 34 percent of the total fish biomass living in Lake Erie. That percentage, though high, is still lower than it is currently in the Illinois River, where Asian carp have caused big ecosystem changes, as well as affected the ways that humans use the river.

Accounting for uncertainty in the model involved interviewing 11 leading experts on Asian carp biology, fisheries and Great Lakes ecology. Statements provided by the experts were then assessed for confidence by uncertainty estimates given by the experts themselves. Scientists describe the approach as similar to that of forecasting hurricanes and including a margin of error estimation.

Results of the work have so far been shared with resource managers across the Great Lakes region to better inform decision-making for Asian carp management. The scientists will next focus their efforts on similar modeling studies to forecast possible effects of the invasive fish species on Lakes Michigan, Huron and Ontario.

Also contributing to the work were scientists from the University of Wisconsin, University of Nevada-Reno, Delft University, University of Notre Dame, U.S. Forest Service, Fisheries and Oceans Canada and the Ontario Ministry of Natural Resources and Forestry. Full results of the investigation are published in Transactions of the American Fisheries Society.

Top image: Two silver carp pulled from the Mississippi River in Missouri. (Credit: Sara Tripp / Missouri Department of Conservation)

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