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Parks officials plan to kill all fish in Miramonte Reservoir
In order to get rid of smallmouth bass that were illegally stocked in a Colorado reservoir officials say they must kill all of the lake's fish.
Colorado Parks and wildlife officials say they'll use an organic pesticide to kill all the fish in Miramonte Reservoir next summer or fall and then rebuild the trout fishery.
In the meantime, bag and possession limits have been lifted on smallmouth bass at the lake.
"Killing all the fish in the reservoir lake is something we wish we didn't have to do, but we know we must," said Renzo DelPiccolo, area wildlife manager in Montrose. "People who illegally move fish into lakes, ponds and rivers are not only committing a criminal act, they are endangering native species, stealing a resource and recreational opportunity from thousands of anglers and negatively impacting the local community."
Miramonte Reservoir is about 10 miles south of Norwood and is regarded as one of the most productive still-water trout fisheries in the state. It's also popular for its crayfish, parks officials said, and adds $1.5 million a year to the economy of San Miguel County.
Smallmouth bass, which are a warm water predator fish, were illegally stocked in the reservoir sometime before 2011 and reproduction has been documented, wildlife officers said. A recent survey showed that in one year smallmouth bass have increased from 5 percent to 44 percent of the fish in the reservoir.
"The bass are now a top predator in the lake. They compete with trout for food and space, and consume trout and crayfish," said John Alves, senior aquatic biologist for Parks and Wildlife's southwest region. "If left alone, the bass could eventually devastate Miramonte as a trout fishery.
"Furthermore the habitat, prey base and water temperature will not support a quality bass fishery in the long term. So, once an illegally stocked fish population has become established, the only recourse is to start over by using a fish pesticide to kill all the fish in a lake," Alves said.
The smallmouth bass also pose a threat to native fish downstream, according to wildlife officials. An agreement among Colorado, U.S. Fish and Wildlife Service and neighboring states restricts stocking of non-native warm water fish without a permit because of the danger they pose to native and endangered fish.
Miramonte Reservoir is located above the San Miguel and Dolores rivers, home to roundtail chub, bluehead sucker and flannelmouth sucker, which are found only in desert rivers of the western United States.
"Native species are needed to help maintain the natural health and balance of any ecosystem. If a species is lost, that affects the health of other plants and animals, and changes a natural ecosystem forever," Alves said.
Treating Miramonte Reservoir will cost at least $100,000, plus staff time, wildlife officials said. The water will be treated with Rotenone, which will kill remaining fish. It breaks down quickly in the environment and poses no threat to vegetation or non-aquatic species, state biologists said.
Anyone with information about illegal fish stocking in Colorado is asked to call the Parks and Wildlife office in Montrose at (970) 252-6000 or Operation Game Thief at (877) 265-6648.
Learn more about fishing in Colorado at the state website.