Invasive Prussian Carp found in Evanston storm pond, city developing management plan

The discovery of invasive Prussian Carp in a northwest Calgary storm pond has experts calling on Calgarians to help prevent their spread in the city's bodies of water.

A pond located in the Evanston community was found to be overrun with Prussian Carp after being reported to the City of Calgary's invasive species hotline on Monday. Calgary Water Services said the discovery is not unique to the city. "This is not a problem unique to Calgary. Invasive fish species have been found in water bodies across Alberta, and Alberta Environment and Parks have identified them as a growing concern throughout the province," the statement read.

Prussian Carp, which look like gray or silver goldfish about the size of a dinner plate, are spreading more frequently in the northern part of the city. The first occurrence of the species in North America was documented in the early 2000s in the Bow River. They have since spread aggressively due to their ability to rapidly reproduce in harsh conditions and negatively impact native fish species.

Invasive fish species populations are managed by the city to prevent them from reaching the Bow River and other local ecosystems. A five-year fish management system is being developed to identify priority locations and control methods.

Since Prussian Carp are not native to Alberta, they are most often introduced when fish are illegally released into storm ponds or other water bodies. "Releasing or stocking any fish in a storm pond is against Calgary's Stormwater Bylaw and can result in a $3,000 fine," the city stated. In Alberta, the penalty for releasing non-native or aquarium fish can reach $100,000 and one year in prison.

Ward 3 Councillor Andrew Yule urged Calgarians to never release aquarium pets or fish into storm ponds, rivers, lakes, or wetlands. He noted that 90 per cent of Calgary's wetlands have been destroyed, but the intricate stormwater pond system that replaced them now leads to local riverways. "I think it's really important that we aren't adding to the problem and reporting any problems we see," Yule said. All unwanted aquarium fish should be returned to a pet store, rehomed, or disposed of responsibly.