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The North Kleenburn Pond had been a good fishery for local anglers, but last winter many of the fish died due to a partial winter-kill. To eliminate a large population of bullheads that had survived, the Sheridan fisheries crew of the Wyoming Game & Fish Department treated the pond with rotenone on Friday, July 6.

The pond had contained smallmouth bass, green sunfish, crappie, channel catfish and black bullhead, but about the only species that survived was the bullhead. Many of these fish were small and not of interest to local anglers.

According to fisheries biologist, Bill Bradshaw, “Since the pond had already experienced a die off of desirable species, we decided to treat it with rotenone so that we could start all over again.”

“Rotenone is a common insecticide that many people use in their gardens to control insect pests,” Bradshaw said. “It also works on any animal that breathes with gills. Rotenone was used widely by South American Indians to kill fish. The chemical prevents animals from respiring so that they can’t convert an important metabolic compound (ADP) into an energy rich compound (ATP). A fish has as much oxygen in its blood after rotenone treatment as before – the fish simply can’t use it.”

The fisheries crew managed to treat the five-acre pond in a couple of hours. One boat crew dispersed the rotenone by pumping water out of the pond and mixing it with the dry rotenone. Another boat crew cruised through the rotenone-treated water to help disperse and mix it into the pond.

Within fifteen minutes after starting to treat the pond, small bullheads and minnows appeared at the surface of the pond. The small bullheads sank to the bottom rather quickly. The one-inch bullheads had been in large balls when they were hit by the rotenone – there were no survivors.

About 20 minutes after the treatment had started, 8- to 12-inch bullheads appeared at the surface. In a short while they were lining the bank.

One smallmouth bass had survived the winter-kill and one green sunfish. Both fell prey to the rotenone.

In two-and-a-half hours, the fisheries crew had finished the treatment of the North Kleenburn Pond. While achieving a 100 percent kill is probably impossible, the bullhead population was reduced to a very small fraction of what it once was.

“After allowing about two weeks for the rotenone to fully decompose, the pond will be restocked with largemouth bass and black crappie,” Bradshaw said. “This species composition will allow anglers to have some high quality fishing opportunities once more.”

Some previous state records have come out of the pond. With a little luck, the pond will again provide record class angling, Bradshaw said.

He noted that the pond would stink for a couple of weeks due to the rotting and decomposing fish. He pointed out that scavengers will eat many of the fish, but there will be enough left over to make the area pretty stinky.

Oh well, a little stench now, but a robust new fishery will soon make the pond appear pretty sweet.

Bob Krumm, of Sheridan, is the Wyoming outdoor correspondent for The Billings Gazette. Contact him