Two invasive species of fish are confirmed in one of northwest Iowa’s most popular lakes, fish that are known for jumping out of the water and walloping passing boaters. Joe Larscheid, chief of the Iowa Department of Natural Resources’ Fisheries Bureau, says a commercial fishing company did a population survey over two days last month. It caught 55 silver carp and 82 big head carp in East Okoboji Lake.
“We really don’t know how many are in the system but our hope is there’s not very many, ” Larscheid says. “You know, 55 silver and 82 big heads seems like a lot of fish but it’s really not. Our hope is that the population is minimal. The thing to take into account, these fish were there all last summer and we didn’t receive one report of ‘flying carp’ and other things that you see with high populations of these fish.” Silver carp have also been caught at Spirit Lake.
He says there is concern these non-native carp species could cause serious damage to the ecology of the Iowa Great Lakes system.
“They can grow very large,” Larscheid says. “The bighead carp and silver carp can get to 60 to 80 pounds in some systems and they directly compete with our game fish. Both of these species eat zooplankton. These are the water fleas people see in the water that our game fish rely on, especially in the larval stages.”
Not only are the invasive fish a threat to the native species, but he says they can also threaten humans, as they have the ability to leap and literally knock people right out of their boats. “They get agitated with boat wakes and there’s pictures of them, in high populations, jumping out of the water and creating a boating hazard,” Larscheid says.
“We’re hopeful the populations are low enough, we’re not going to see the effects of competition and we haven’t seen the impacts on boating recreation yet.” The D.N.R. is working with local private and public partners to pay for an electronic fish barrier that would keep more carp from getting into the lake.
A large portion of the $700,000 needed for the barrier has already been raised.