Ken Kester, who built the contraption, calls it a "fish launcher."
Kester sets up the slingshot at Lock and Dam 14, in Le Claire, Iowa. He told the Quad-City Times it can toss fish far out into the channel where the water is calmer.
"You have to get the fish out there a couple hundred feet, into that comfort zone for the eagles," Kester said.
Jeff Harrison, a conservation officer with the Iowa Department of Natural Resources, said flinging fish into the river is fine as long as the fish come from the local pool of water. Le Claire is 15 miles northeast of Davenport, on the Illinois border.
Photographers line the riverbank elbow-to-elbow on nice days to make images of the eagles, and the slingshot ensures more dramatic pictures.
Even though it doesn't hurt the eagles to serve up fish, Harrison wonders about the ethics for the photographers.
"I don't know if I agree with it," he said. "Some of these photographs show up in some pretty big magazines, and they are more or less staged."
And Kester, who works in the railroad industry but considers photography a serious hobby, said there are limits to his invention. Recently, after a couple hours of flinging fish, the eagles stopped grabbing them.
"I think they got full," he said.
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