Gold Fish Causing Problems In Chaska Lakes

Some Chaska lakes are dealing with an invasive species typically found in household aquariums, reports John Lauritsen (2:07). WCCO 4 News At 6 - June 3, 2021

Video Transcript

- Some Chaska lakes are dealing with an invasive species typically found in household aquariums. In 2019, goldfish were first detected in Big Woods Lake and Lake Hazeltene. Scientists say they disrupt the ecosystem, and the concern in Chaska is that they could make their way to the Minnesota River. John Lauritsen shows us what's being done to stop the invasion.

JORDAN WEIN: Today, we are on an electro fishing boat. Not many of these in the states.

JOHN LAURITSEN: On Big Woods Lake, it's a different kind of fishing opener.

JORDAN WEIN: It's mostly just goldfish.

JOHN LAURITSEN: The theory is a couple of years ago a pet owner released a goldfish or two into this lake, not knowing it would lead to a population explosion. So now, environmental scientistist Jordan Wein and his crew from WSB Engineering are using a method called electro-shocking to learn more.

JORDAN WEIN: And that power sends some electricity through the water and it stuns fish just momentarily, enough for two netters to hang off the front of the boat and take some dip nets, scoop out whatever we're looking for.

JOHN LAURITSEN: It's a catch-and-release effort, but the fish will be tagged before they're released. Scientists want to know where they spawn and where they're going. What's happening here is part of a three year plan. This is year one of the plan, with the goal of not necessarily eliminating the goldfish, but managing them.

TIM SUNDBY: Last fall we removed close to 100,000 goldfish.

JOHN LAURITSEN: For the fish, its strength in numbers. And Tim Sundby of Carver County Water Management, simply wants to find a way to bring their numbers down enough so vegetation and fish, like bluegills and sunnies, can return.

TIM SUNDBY: If you're familiar with rough fish, they really upset the whole ecosystem. So they just stir up that sediment and they can dig. Carp can dig 3 feet down.

JOHN LAURITSEN: Without a management plan, they're worried the fish could make their way to the Minnesota River, which means time is of the essence.

JORDAN WEIN: We'll have some year to year to year comparable data to see if we're making a difference.

JOHN LAURITSEN: In Chaska, John Lauritsen, WCCO 4 News.

- Carver County Water Management is hoping what they learn from this project can be applied to other Minnesota lakes also dealing with goldfish infestations.