Town of Okotoks launching campaign to remove goldfish from storm ponds

Most people probably think of goldfish as harmless pets found swimming in living room tanks and backyard ponds, but some have found their way into stormwater systems across the province and are threatening to become a real problem.

Some goldfish have grown to the size of dinner plates

Koi and goldfish released into storm ponds are posing a real problem across the province. The Town of Okotoks is taking measures to try and remove them. (Rebecca Baldwin/Alberta Environment and Parks)

The Town of Okotoks is taking measures to remove goldfish that have found their way into nearby storm water systems.

Most people probably think of goldfish as harmless pets found swimming in living room tanks and backyard ponds, but they have become a growing problem.

"We expect they got in there from residents perhaps who had backyard ponds with koi or goldfish and didn't want to over-winter them, so may have released them into the pond," Okotoks parks manager Christa Michailuck told the Calgary Eyeopener on Monday.

"Unfortunately they are hearty enough to over-winter here and are able to reproduce and do quite well.

"We've seen some sizeable ones.... It's a fairly new problem but maybe the size of small dinner plates or larger."

The provincial government launched an awareness campaign last year called Don't Let It Loose, aimed at informing Albertans about the dangers of releasing invasive species into waterways.

Goldfish are seen in a storm pond near Okotoks. The town is taking measures to remove the fish. (Town of Okotoks)

Officials will need more than the traditional rod, reel and bait to get rid of them.

"It seems like our best option to control the fish is to lower the pond levels in a time of year when there's little rainfall to fill them back up again and then with reduced water volume we can harvest the fish more easily through either electrofishing or netting," said Michailuck.

"And the few fish that maybe get left behind which could reproduce again, we would treat that reduced volume of water with a fish pesticide.

"It's more toxic to fish, and it has some toxicity to aquatic insects, but it's got very little toxicity to other mammals, birds and other amphibians."

At least two storm water ponds in Okotoks are known to be affected and Michailuck said the town is doing presence-absence monitoring to see if they problem is more widespread.

Officials are worried some of the fish could make their way into the Sheep River.

"Yes, absolutely," said Michailuck.

"The way a storm water pond is built it's essentially a settling area for runoff from streets and roads then the overflow water — the clear water — after it's settled would go through the outflow device back to the Sheep River."

Only 1 person qualified

Michailuck said officials want to remove the fish as soon as possible, but there is currently only one person qualified to apply the pesticides to storm ponds in Alberta.

"The province has indicated there's going to be offering additional training and it was supposed to be this June but they've pushed it back to September," she said.

"And it's kind of closing our window a bit small in order to get the treatment done while the optimal time to do it would be before the end of September.

"In the meantime, they keep on reproducing and growing, it's a challenging situation."

With files from the Calgary Eyeopener