“Asian carp” actually refers to two species of exotic fish, not one. As they spread throughout the nation’s rivers, both pose threats to native fisheries.
As it turns out, though, there seems to be a big difference in their vulnerability to predation. That’s bad news for bighead carp, which grow larger, feed more exclusively on zooplankton, and are less abundant. And good news for the smaller silver carp, which have become infamous for endangering boaters with their leaping antics.
Researchers at the Illinois Natural History Museum and University of Illinois put small samples of both into experimental pools, along with bluegill, gizzard shad, and golden shiners. Largemouth bass in those pools ate more bighead carp than any other species, including silver carp. Scientists hypothesized that this may mean that young silver carp are more “street smart” than their bighead cousins.
While it’s good to know that bass can and likely do eat these invaders, especially bighead carp, whether this predation will help control them remains to be seen.
“Although new research is confirming that native fish can and do consume Asian carp, this not mean that all is well,” cautioned the Michigan State University Extension (MSUE). “In the LaGrange Reach of the Illinois River, at least seven native fish are preying on Asian carp. Even so, this reach has one of the highest densities of silver carp recorded anywhere in the world.
“Native plankton-eating fish like gizzard shad and bigmouth buffalo have declined and the long-term effects on gamefish are still uncertain.”
In 2008, biologists estimated more than 5,000 silver carp per mile in that nearly 80-mile stretch of the river, with a biomass of 705 metric tons.
“In the Great Lakes, we already know that native fish are adapting to non-prey items like quagga mussels and round gobies,” MSUE continued. “We also know that predation has not been enough to eliminate these species or prevent their negative effects. The same is likely true for Asian carp.”
(This article appeared originally in B.A.S.S. Times.)