According to reports, teams of fishermen came with an apparently bizarre array of equipment, including powerful searchlights, loud airboats and scores of bows and arrows. Last month, their tournament ended on the Mississippi River.

And since then, there have been a lot of complaints that federal regulators were thinking about tougher restrictions on the bowfishing, which is a fast-growing sport in which anglers shoot fish using arrows that are attached to fishing line.

According to Tim Mason, an environmental activist from McGregor, Iowa, who comes to the place with his wife, "It turned night into day and blasted our ear drums like we were on an airport runway".

The grumbling started shortly after members of the Bowfishing Association of America assembled in July for a world tournament in northeastern Iowa and western Wisconsin, where the Upper Mississippi River National Wildlife and Fish Refuge is located.

There were 43 teams in the competition, and many of them made use of boats with aircraft-style propellers and engines to move quickly across the water and low-lying land from evening till early morning. They targeted only invasive fish like gar and carp. Cash prizes were given to teams with the highest number of fish and the most massive 20 fish.

The contest was thrilling for the 130 participants who came to the place even from distant areas like Alabama. Some cabin dwellers and campers present along the river complained regarding lights, loud noises and potential troubles to wildlife and habitat.