Biologists from the state Department of Natural Resources offered a way yesterday to deal with an invasion of unwanted goldfish in a Columbia pond: bring in bigger fish.
Three fisheries experts with a large net waded into the pond on Montgomery Run Road at the request of the county Department of Recreation and Parks, surveyed the aquatic life and suggested largemouth bass to take care of hundreds of non-native goldfish and several large koi that are disturbing the ecosystem of the pond.
It was a welcome solution to county natural resources officials eager to address the invasive species as soon as possible. "We can nip it before it washes downstream and perpetuates the problem," said Brenda Belensky, a county natural resources manager.
The parks department has been concerned about the pond in The Villages of Montgomery Run - where darting schools of bright orange goldfish are visible from shore - since this spring. That is when Brian Cannon and his 10-year-old son, Brendan, were going to the pond to listen for frogs as part of the Frogwatch USA monitoring program.
"Our pond ... really had no frog life," said Cannon, who lives in Ellicott City. "It was pretty disappointing for my son."
The Cannons reported the goldfish and the lack of amphibians they spotted to their coordinator, Sue Muller, a natural resources technician with the parks department, and she sought expert advice.
Yesterday, Charlie Gougeon, Todd Heerd and Mark Staley put on rubber waders and climbed into the pond to pull a net through the water near the shore. They scooped up baby goldfish and crawfish, which they released, but found no evidence of other fish species.
Gougeon recommended adding bass that will eat the goldfish, plus bluegills that will keep the pond in balance by eating insects and providing a food source for the bass. Fishing will keep the bass in check long-term, he said, as long as people wait until the fish are large enough and don't overfish the pond.
The fisheries biologists also confirmed what the county staff had thought, that the invaders were introduced by people. "They thought they'd be nice to" the fish, Gougeon said.
Careless actions by people have helped spread numerous other invasive species, naturalists say. In Howard County, hydrilla likely dumped from a fish tank is filing up the pond at Font Hill Wetland Park and unwelcome carp are swimming in Guilford Pond near Savage.
Last year, the state Natural Resources Department had to poison a Crofton pond to stop voracious northern snakehead fish let lose by their owner.
Across the state, more than 75 harmful, non-native species are moving into natural areas on public and private land, according to the Maryland Invasive Species Council. They spread aggressively and reproduce quickly, outcompeting native species.
Belensky said she is pleased that her department might be able to control the goldfish through natural means.
"It will be a good indicator when my volunteers hear frogs again," she said.