Invasive fish count in Firelight Pond dwarfs city estimates

By Al Beeber - Lethbridge Herald on September 10, 2022.

Herald photo by Al Beeber Dead koi and goldfish are seen floating in Firelight pond in Copperwood on Friday. The pond was sprayed with rotenone in an effort to eradicate the invasive species of fish.

LETHBRIDGE HERALDabeeber@lethbridgeherald.com

Firelight Pond in the westside subdivision of Copperwood may look innocuous but underneath the surface of its water has lurked a potential ecological disaster for rivers and lakes.

That threat is from the invasive non-native goldfish and koi that have been introduced into city storm ponds.

By the end of the work day Friday, the City expected to have removed about 50,000 fish from the pond after the water was treated with Rotenone.

Rotenone, said City Natural Resources co-ordinator Jackie Cardinal, is a substance that blocks oxygen exchange at the gills and only affects fish.

It is not hazardous to humans or other animals.

Cardinal said there were more fish in the pond than the City thought.

On Thursday alone, crews removed about 11,000 fish from the north end of the pond. On Friday morning, hundreds of dead goldfish and koi could be seen floating around the edges of the pond.

Cardinal said “I didn’t think there were this many in there. I knew there was a lot but I didn’t think we were in the tens of thousands,” she said early Friday morning.

Crews were scooping the fish out and putting them into plastic containers. Some of the fish were as long and wide as two human hands.

“If this was a natural pond or a natural water body, they would completely out-compete any native fish species. They eat everything, they eat all the vegetation, they muck up the water so there’s less oxygen in the water which impedes the growth of native fish. They’ll eat the eggs of native fish, they’ll eat anything that fits in their mouth,” said Cardinal.

“We haven’t found any native fish in here which we are very very lucky about. But the risk is if this pond overflows, it goes to the river and it impacts the native fish in the river and that’s why we’re treating it,” she said.

From Sept. 1 until Friday water pipes ran from the south side of the pond onto Moonlight Blvd. West with Rotenone spraying being done Thursday and Friday.

Follow @albeebHerald on Twitter

Comments are closed.