Goldfish threaten pond life

Invasive: The traditional pets are problem residents of a Howard County park.

July 16, 2004|By Sandy Alexander | Sandy Alexander,SUN STAFF

Jacob Cherian waded into a pond in Sewells Orchard Park in Columbia this week searching for invaders.

With help from Carl Spicher, another volunteer, he pulled a net through the shallow water Tuesday, hoping to corral some of the 50 large goldfish that have taken up residence in the pond.

"They were huge," said Susan Muller, a natural resources technician with the Howard County Department of Recreation and Parks who spotted the fish this spring. She estimated they were 18 inches to 24 inches long.

Muller, part of a small staff that oversees hundreds of ponds and other natural areas in the county, believes that someone dumped the fish into the pond, although she doesn't know when. She does know they don't belong.

"When you introduce species, you upset the balance of the ecosystem," Muller said.

Goldfish eat frog eggs and tadpoles, Muller said, and compete with native fish that provide food for birds and turtles.

Invasive species are a problem throughout the country, as foreign plants, insects, animals and diseases invade natural areas. Most lack indigenous predators and are able to grow fast, reproduce swiftly and out-compete beneficial species that are part of the food chain.

Nonnative species can also interfere with agriculture, parks and open spaces, costing individuals and government agencies significant amounts of money. Maryland spent $1.8 million battling invasive species in 2000, the last year for which data are available, according to the Maryland Invasive Species Council.

Some species are introduced accidentally, like sudden oak death, a tree disease that is spreading through the sale of nursery plants. Others were added to the environment on purpose before anyone knew better, such as the fast-growing multiflora rose, which was thought to make a good natural fence.

And some are set free by pet owners who might think they are being kind.

"Intentional release of species is a real problem," said Jonathan McKnight, associate director for habitat conservation with the Maryland Department of Natural Resources.

The most notorious recent example is the northern snakehead, an aggressive, land-traveling fish that was released in a Crofton pond, forcing the DNR to poison the water two years ago. Snakeheads have since turned up in the Potomac River.

Local and natural resources police also caught a caiman, which is like a small alligator, in Seneca Creek in Bowleys Quarters this month.

McKnight said goldfish will survive in Maryland ponds and disrupt the natural system. But, he said, they are not among the most problematic species. "Fortunately, they are unlikely to attack the children," he said.

In Howard County, the parks department has been trying to reclaim its ponds for a few years. Last summer, the department invited staff from the DNR to combat goldfish that were found in a pond in the Villages of Montgomery Run, an Ellicott City neighborhood. The state experts brought in largemouth bass to eat the goldfish, which appear to be under control this year, Muller said. A few unwanted koi are still loose in the pond.

The county parks department has also treated the pond at Font Hill Park in Ellicott City more than once for hydrilla, a bushy water plant that is commonly found in aquariums but chokes out other plants in the wild.

When she saw the goldfish at Sewells Orchard, Muller sent an e-mail seeking volunteers. She already uses willing community members to monitor stream quality, watch bluebirds and count frogs. Since the spring, Cherian and Spicher, both of Columbia, have been spending their Tuesday afternoons trying to scoop up the unwanted goldfish. A few other volunteers help out on occasion.

This week, Cherian waded into the shallow water and assembled his homemade net, which is weighted on the bottom with a chain and supported on top by plastic foam "noodles" commonly used as pool toys.

Spicher, standing in the long grass on the other side of the pond, pulled the net into position with a string and then Cherian dragged it through the water, closing the loop and trapping the fish

Even though Cherian spotted one of the large goldfish within the circle of the net, by the time he scooped out sunfish and other harmless creatures, it had gotten away.

"The most we have gotten is three to five at time," said Cherian, who has kept several of the fish he has caught, adding them to a decorative pond at his home that has no connection to other waterways. Muller has a list of other people willing to adopt any more fish that can be caught.

Both men say they enjoy nature and like working in Sewells Orchard. Cherian, a physician and fish fan, sees it as a way to relax while Spicher, retired from the National Security Agency, said, "It's fun getting wet and dirty."

Both say they will continue to trap the fish for the rest of the summer.

Muller said she hopes that the public starts to catch on to the difference between native and nonnative species.

The latter "don't belong in your local park," she said.

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