BOULDER, Colo. - Colorado Parks and Wildlife says someone released goldfish into Teller Lake #5 off Arapahoe Road in Boulder and created an invasion.
The exotic species, which were first noted by Boulder Open Space Rangers on March 13, now number about 3,000 to 4,000 and will likely need to be removed to maintain the integrity of the lake. CPW spokeswoman Jennifer Churchill said they may need to drain the lake to remove the goldfish or using electro fishing, where they stun the fish and remove the invasive species.
"Goldfish are not a native species and are very harmful to the local aquatic ecosystem," said Kristin Cannon, district wildlife manager for Boulder. "We strongly encourage the public not to dump their unwanted pet fish in our waters. It is bad for our environment, as well as illegal."
In November 2012, the removal of koi goldfish from Thunderbird Lake in Boulder put a spotlight on the threat exotic species represent to Colorado's aquatic wildlife. The electro fishing effort yielded 2,275 nonnative goldfish, which had likely been reproducing in the water for two to three years, based on the age classes of fish removed. What likely began as the deposit of unwanted pets into the lake grew into a problem of enormous proportions.
"Most people don't realize the far-reaching effects of introducing exotic species to the environment," said Ken Kehmeier, senior aquatic biologist for CPW.
"Nonnative species can be devastating to native populations by causing disease outbreaks and creating competition unbalance. It's an issue that anyone concerned with our environment should know about."
Also of concern is the "bucket brigade"-- anglers who choose to dump sport fish of their choosing into Colorado waters. While some nonnative fish are stocked at times, aquatic biologists only do so after a rigorous biological assessment to determine what can be stocked and where for a balanced ecosystem.
"We work closely with anglers via creel surveys and check with local bait shops on a regular basis to find our anglers' desires and aspirations for fishing in the state," said Ben Swiggle, a northeast region aquatic biologist. "We carefully stock for optimum conditions to get people outdoors, offer recreational opportunities, and to better the habitat of the state."
Since word of the goldfish invasion first broke, people have been calling to ask if they can net some goldfish for their ponds, but Boulder parks officials say they do not want people removing these goldfish, because it could disrupt the natural environment around the pond.
When the goldfish are removed they will probably be given as food to a local raptor rehabilitation program.