Calgary, Alta. (Rural Roots Canada) – The invasive fish species, Prussian carp, has been found in a stormwater pond in northwest Calgary.

Residents of the northwest community of Evanston say the stormwater pond appears to be full of Prussian carp, a sign the highly invasive species is persisting through Calgary’s stormwater system.

Prussian carp is an introduced fish species known to disrupt aquatic ecosystems and pose a potential threat to native fish. Native to central Europe and Asia, it’s unknown how this fish species was introduced to Alberta. It’s suspected it was through a ‘goldfish’ release – accidentally or intentionally dumped into local waterways when people illegally release aquarium pets or other unwanted fish into storm ponds and waterways.

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Alberta was the first jurisdiction in North America found to have Prussian carp, which has since spread to Saskatchewan via shared waterways. It continues to spread due to natural dispersal and illegal introductions and has been found in multiple watersheds, including the Bow, North Saskatchewan, Oldman, Red Deer, Rosebud and South Saskatchewan waterways.

Prussian carp can reproduce asexually, meaning a single fish can quickly establish a population. It can survive in tough conditions, can tolerate poor water quality, breed rapidly, and compete effectively for food and habitat. Once established, they are difficult to remove and can spread quickly, which is why the city is treating the Evanston situation as more than a one-time clean-up issue.

Storm ponds in Calgary are a part of the city’s infrastructure. They are designed to hold runoff, reduce flooding and improve water quality before water moves back into the Bow River system. The Prussian carp situation has triggered a city-wide approach to managing invasive fish in Calgary storm ponds, according to a statement from City of Calgary Ward 2 councillor Jennifer Wyness, who says the city is developing a fish management and control plan.

“Evanston is not facing this alone,” said Wyness. “I will keep you updated as the City releases their 5-year plan for invasive species in our waterways later this year.”

Releasing fish into a storm pond is illegal and can result in a $3,000 fine under Calgary’s stormwater rules.

The city is asking anyone who sees fish in a storm pond to report it to the 311 line so city staff can investigate.

Photo credits: Government of Alberta – Invasive Fish Species Prussian carp website