Keep Our Lake Clean~

3,000 Goldfish! Dumped Aquarium Pets Multiply in Boulder Lake

 

They multiply like … fish! Apparently, a handful of goldfish dumped into a lake in Boulder, Colorado, just three years ago have reproduced and now number in the thousands.

The explosion of these exotic fish, which are not native to anywhere in North America, has biologists worried and trying to figure out options for the animals’ removal.

“Based on their size, it looks like they’re 3-year-olds, which were probably produced from a small handful of fish that were illegally introduced into the lake,” Ben Swigle, a fish biologist at the Colorado Parks and Wildlife (CPW), told Live Science.

A ranger noticed the 3,000 to 4,000 goldfish a couple of weeks ago in Teller Lake #5 off Arapahoe Road and reported it to CPW.

“If they escape and move downstream, they’ll directly compete with our native species, all of which were here before the land was even settled,” Swigle said.

There are about three or four fish species considered threatened or “species of concern” living downstream from the lake; they include the stonecat (a miniature version of catfish), the common shiner and the brassy minnow, Swigle said. These fish feed on plankton and small insects, the same diet as goldfish, he added.

“If they [the goldfish] explode and get downstream and potentially explode, there they are competing with these fishes not only for spawning habitat but also for foraging resources,” he said.

In addition to supplanting the native species, these koi goldfish may be carrying viruses. Unlike the fish from fisheries that are used to stock lakes, pet goldfish are not rigorously tested for disease, Swigle said. Aquarium fish could carry viral hemorrhagic septicemia virus (VHSV), responsible for killing off thousands of fish in the Great Lakes and bacterial kidney disease, which has been seen in aquarium fish, Swigle said.

CPW scientists are currently considering three options for dealing with the exotic goldfish explosion. Officials could drain the lake and leave it dormant for a while, use electricity to stun the fish and then net them out, or use a chemical called rotenone that interferes with respiration to “remove” the fish.

If the fish are physically removed, they could be brought to a raptor sanctuary and fed to injured hawks, ospreys and bald eagles, he said.

This isn’t the first time such fish have turned up in high numbers in the area. In November 2012, some 2,275 koi goldfish had to be removed from Thunderbird Lake in Boulder, after a few were likely dumped there as “unwanted pets” two to three years earlier, according to a CPW statement.

“Goldfish are not a native species and are very harmful to the local aquatic ecosystem,” Kristin Cannon, district wildlife manager for Boulder, said in the CPW statement. “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.”

One way to get rid of unwanted aquarium fish is to call the pet shop that sold the fish and try to return it, said Sue Williams, an evolution and ecology professor at the University of California, Davis Bodega Marine Laboratory, who spoke with Live Science for a past article.

Pet owners wanting to dispose humanely of their aquarium fish may want to consider the guidelines put forth by the American Veterinary Medical Association in its 2013 report for euthansia of animals. Some acceptable methods, according to the association, include a process that involves immersion with anesthetic solutions or injection with a solution that contains ketamine. The report also describes other methods that are acceptable when certain conditions are met, and additionally lists unacceptable euthanasia methods.

Tempted to flush your fish? That may not be a great idea, either, as the hardy fish can make it to natural waterways and wreak havoc, Williams said in the past article.

Original article on Live Science.

 

Fertilizer and Lakes

By Bonnie Ennis, Colorado State University Cooperative Extension Agent, horticulture

What comes around goes around, and nothing applies to this theory more clearly than the water we use and drink.

Overwatering and mis-use of chemicals contaminate water supplies. Home gardeners can play a key role in protecting water quality by making wise decisions about fertilizer and pesticide use, as well as about watering practices.

Why home gardeners? Recent studies show that homeowners use more pesticides per acre than farmers use on their fields. One study indicates that 27% of all pesticide use is in urban areas. Such studies de-bunk the notion that agriculture is the only culprit in the war of words about chemicals and the environment.

The concept is simple: Water falls as rain and snow. It seeps into the groundwater or flows directly into streams, taking chemicals with it. Ultimately, it is withdrawn, treated and used for drinking or landscape irrigation. Wise management in the home landscape can reduce potential water quality problems and create safer supplies.

Overwatering

Plants need water for moisture and to dilute and carry fertilizers and pesticides into root zones.

Overwatering carries fertilizers and pesticides beyond root zones into ground water stored in alluvial or bedrock aquifers below the soil surface. Water in these aquifers can interact, sharing chemical contaminants. Aquifer water also interacts with stream water.

Overwatering also results in storm drain run-off. This run-off flows untreated through underground pipes to the nearest creek or river, again carrying pesticides and fertilizers.

Down the Home Drain

Pesticides and fertilizers flushed down indoor drains flow to the nearest sewage treatment plants.Sewage treatment plants do not remove pesticide or fertilizers. DO NOT DUMP PESTICIDES OR FERTILIZERS DOWN INDOOR DRAINS.

Nitrate nitrogen is a common component of landscape fertilizers which, in concentrations greater than l0 milligrams per liter of water, is toxic to pregnant women and small children. Treated household waste effluents in the South Platte River already create levels of 20-30 milligrams of nitrates per liter of water. Nitrate fertilizers flushed down home drains will only increase these high nitrate levels.

Who Uses Groundwater and Open Channel Water?

The answer is almost everyone. Glendale depends l00 percent on wells that tap into the Cherry Creek alluvial aquifer. Thornton, Northglenn and Arvada supplement their water supply from wells drilled into other aquifers. Chemicals, that leach through the soil, can contaminate these wells.

Arvada, Northglenn, Thornton and Golden also take water from Standley Lake. The lake is fed by Clear Creek, a stream that receives both untreated storm drainage and direct soil run-off that contains pesticides and fertilizers.

What Can We Do to Help?

As home gardeners gear up for the summer growing season, we can think twice about use and disposal of fertilizers and pesticides. To prevent chemical contamination, water lawns following ET recommendations from the Denver Water Department. Or water only when soil is dry and then just until root zones are moistened. Turn off water before run-off occurs. Allow water to soak into soil before re-applying. To reduce run-off, aerate heavy soils, especially on slopes.

Use great caution as you dispose of chemicals. For a safer environment:

• Use chemicals according to label directions.

• Water only as needed.

• Do NOT dump chemicals down the drain, in the garbage or onto the ground.