Invasive goldfish proliferating in Saskatoon storm ponds

The City of Saskatoon is battling an invasive species in its storm ponds.

More than 450 kilograms, or 1,000 pounds, of invasive goldfish of various sizes were collected from three different storm ponds in the city last week.

"If you're standing on the edge of the pond on a sunny day, you can often quite easily see the large numbers of goldfish," said Brodie Thompson, an engineering manager with the city.

Thompson said goldfishare an "adaptable and tenacious" species, making them difficult to get rid of.

The city has decided to go with Rotenone, a fish poison, to address the problem. It was added to the water recently.

"It doesn't remove oxygen from the water, but it actually inhibits the fish's ability to extract oxygen from the water," said Thompson.

According to the city website, the Rotenone presentsa "very low risk" tohumans and other animals.

They're just so good at taking over that they push native fish species out of their niches- Christopher Somers, Professor of Biology at the University of Regina

Christopher Somers is a professor of biology at the University of Regina and studies invasive fish.

"There's really only one way that goldfish get into these sorts of closed systems, and that is by people getting rid of unwanted pets," said Somers.

Somers says the biggest concern is that some of these ponds could become "reservoirs of invasive species" that would flow into bigger bodies of water like the south Saskatchewan River.

The city advises residents to contact a local pet store that would accept the aquarium pets rather than disposing of them inbodies ofwater.