Alberta's waterways flooded with invasive goldfish; province issues warning and fines

Schools of invasive goldfish — some the size of dinner plates — are plaguing Alberta's waterways, and the provincial government is sounding the alarm on the threat to native ecosystems.

Goldfish have been detected in more than 100 locations throughout Alberta, with new locations added to that list every year. According to the province's aquatic invasive species specialist Nicole Kimmel, this isn't accidental. "People are actually intentionally dumping them into our waterways, and they are overwintering and thriving and finding ways to reproduce," she said.

The province's "Don't Let It Loose" campaign aims to curb the illegal releasing of species into waterways — a crime that can result in fines of up to $100,000 and up to one year in prison. Environment Minister Grant Hunter put it plainly in a Monday news release: "Goldfish belong in aquariums, not in Alberta's waters. Don't let it loose."

Goldfish pose significant risks to native fish because they're highly adaptable and can eat anything that fits in their mouths. Many native fish are pickier about food and breeding sites. Goldfish also have no problem surviving Alberta's harsh winters — a single goldfish can produce an estimated 40,000 offspring in just three years. "Those competitive advantages give [goldfish] every opportunity to thrive," Kimmel said.

Once goldfish establish themselves, culling is the only option: the entire fish population has to be destroyed through chemical treatments or draining. Mandrak, a University of Toronto invasive species researcher, notes that storm-water management ponds are prime locations for goldfish to spawn and spread. "Because these are adjacent to houses, they're convenient places for people to release their goldfish," he explained. "They're typically a little warmer than our lakes and rivers, and that means goldfish reproduce at a higher rate."

Kimmel urged residents never to release anything into water that didn't come from there: "People might think that they're just dumping goldfish, but actually they might be introducing snails, fish disease, plant fragments that can also take over a water body in Alberta."