ST. GEORGE — If you've done any fishing lately at any of the community fishing ponds and even some local reservoirs, chances are you may have seen or even caught an invasive fish. Vibrantly colorful and surprisingly large koi are unmistakable in Baker or Ivins Reservoir, while smallmouth bass continue to frustrate wildlife officials as they try to monopolize Quail Creek Reservoir.
According to the Utah Division of Wildlife Resources, nearly all community fisheries in the St. George area now host colonies of koi fish. Southern Region Aquatic Program Manager Richard Hepworth said these fish are usually introduced by families and individuals dumping their unwanted pets in the nearest pond or waterway.
"Koi are not very desirable for table fare, and they compete with species like rainbow trout that people tell us they want to catch," Hepworth said. "Smallmouth are a very direct threat to the native species within the Virgin River system. If they got out into the river system, not only would they compete, but more likely they would prey on and eat these native species that we're trying to keep from being endangered. "
In 2015, the population of smallmouth bass at Gunlock Reservoir got so out of control that the Division of Wildlife Resources treated the entire reservoir with rotenone. In the years following, Kolob Reservoir also received a similar treatment to deal with its runaway invasive species problem.