CARVER COUNTY, Minn. — Some communities in Minnesota and other parts of the U.S. are shocked that some giant goldfish have become a big problem.
The goldfish found in Burnsville, Minnesota, are the size of footballs.
In nearby Carver County, experts say there are more goldfish in the wild than you can imagine.
“We got out tens of thousands of them in just a few days in the fall. In the springtime, we took out thousands of them in that same year,” Jordan Wein said.
Wein works for WSB, a firm hired by Carver County to survey the goldfish in the area lakes.
"These hearty invasive fish survive through the winter, those really tough times, and they are the first ones and the only ones back in the springtime and basically take over the lake," Wein said.
The problem is too many people dumping goldfish and other pets into lakes and other habitats.
Goldfish are popular, low-maintenance at-home pets. But in the wild, they cause real mayhem to the environment. The fish kick up dirt and mud from the bottom of lakes, which keeps sunlight from reaching plants. That can lead to dirty, algae-filled lakes that native fish can’t survive in.
The county believes there are hundreds of thousands of goldfish in its lake.
“We should definitely not be releasing our pets into the wild. There are several different reasons why we shouldn’t do this. In the vast majority of cases, it just spells certain death for that pet that we might have cared about,” said Anna Sheer, a biological sciences professor at the University of Denver specializing in invasive species.
“Usually, the kind of animals that we keep as pets are in the pet trade because they are easy to take care of, they’re very hearty,” Sheer said.
She says a species can take over an ecosystem, especially if there's a lack of natural predators.
Sheer says that's the case for the Burmese python in Florida, another "should-be pet" released into the wild.
“There’s nothing that is killing them in Florida. That ecosystem hasn’t evolved with Burmese pythons, and so their natural predators and diseases simply aren’t present there,” Sheer said.
Burmese pythons are devastating ecosystems in parts of South Florida, including the Everglades, because there is no predator to keep their population in check. They also became an issue because of the pet trade.
The best course of action is to not let your pets loose in the wild if you no longer want to care for them or are unable to.
“I would recommend taking that pet back to where you bought it,” Sheer said. “And let them know, 'I don’t want this anymore,' and can you either dispose of it or advise me how to dispose of it in a safe way."
U.S. Fish and Wildlife suggests donating your unwanted fish or animals to a pet store, school or other learning institution.
But for the sake of the environment, don't release an animal in an area where it doesn't belong.
“I think the saying goes, an ounce of prevention is worth a pound of cure,” Wein said.