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Invasive goldfish proliferating in Saskatoon storm ponds

In the past week, the City of Saskatoon has collected more than 450 kilograms, or 1,000 pounds, of invasive goldfish in its storm ponds.

Residents advised not to dispose of pets in bodies of water

Moreen Mugerwa · CBC News ·
Pictured is one of the largest goldfish found in a storm pond in Saskatoon. Most were five to seven centimetres, or two to three inches, in size and weighed less than a half a kilogram, or less than one pound. (City of Saskatoon)

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 goldfish are an "adaptable and tenacious" species, making them difficult to get rid of. 

City crews were seen here at a pond in Saskatoon in the process of removing the invasive goldfish. (Travis Reddaway/CBC)

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 presents a "very low risk" to humans 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 in bodies of water.

LISTEN | Brodie Thompson and Christopher Somers spoke with host Leisha Grebinski on Saskatoon Morning: 

ABOUT THE AUTHOR

Moreen Mugerwa

Moreen Mugerwa is a journalist with CBC Saskatchewan. She holds a bachelor's degree in journalism from the University of Regina. She works as a portrait and lifestyle photographer in her spare time.

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