Goldfish derby gives invasive species the hook

By Justin Seward - Lethbridge Herald on July 11, 2023.

The City of Lethbridge welcomed residents to participate in Goldfish Derby Days at Chinook Lake Park on Saturday.
The event not only allowed for attendees to catch goldfish and koi, but it was an educational opportunity on what those types of invasive fish cause in terms of issues in the city’s storm ponds.
“Chinook Lake here has an extensive goldfish population that’s been here for a number of years and we’re just here to let people know that they’re not OK and not to release them from their aquariums or their back yard ponds into the ponds here,” said Jackie Cardinal, natural resource coordinator for the City of Lethbridge’s parks department.
“And it’s a fun event. We’ve got some games out and tons of people out already that are catching some and then just letting people know what to do with them. So to put them in the trash or we can take care of them. We’ll put them in our trash cans and get rid of them.”
Cardinal said goldfish have no natural predators here and the pond is kind of an isolated system, when asked about the extensive goldfish population.
“It receives water to come in, but it doesn’t really flow out unless there’s an extensive storm system or a storm event and they have no natural predators here,” said Cardinal.
“They can lay over 1,000 eggs in each cycle. So they’re like rabbits.”
Cardinal said goldfish and koi are really bad for the environment.
“They will take over a water body and they’re really bad for our native fish,” she said.
“They carry parasites, they eat all the available food. So there’s not as much left for everything else that should be in here and there’s the risk they will end up in the river if they end up in a storm pond because our storm ponds release directly into the river without treatment. So if the pond overflows, there’s a good chance fish go with them.”
Matthew Hrudey was fortunate enough early on to catch a goldfish.
“It was I guess exhilarating, catch of a lifetime” said Hrudey on his first catch of the day.
“But, you know, it was fun.”
Hrudey said it’s really good for the pond for people to take goldfish out.
“They’re not supposed to be here,” said Hrudey.
“People get to go fishing and it has the benefit of removing goldfish from the pond and keeping the biodiversity of the pond good.”
Hrudey’s friend Braden Liptack had eight goldfish caught by late morning.
“I learn a bit about the goldfish, learn new things about new fish and fishing techniques and about how the goldfish are impacting all the ecosystems in the pond and the river and stuff,” said Liptack.
It was expected that 50,000 to 60,000 fish would be pulled from Chinook Lake between the derby and the City’s chemical treatment in the fall.
Between last year’s derby and the city’s treatment of Firelight Pond last fall, there were over 85,000 fish pulled from that pond.
There will be a second derby on Aug. 3 from 3 to 8 p.m.

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