B.C. conservation group warns of goldfish invasion in Kelowna pond

An environmental conservation group says goldfish, a provincially-designated invasive species, are now thriving in a popular pond in Kelowna, B.C.

Lisa Scott, executive director of the Okanagan and Similkameen Invasive Species Society based in Summerland, B.C., says local residents have spotted glints of gold under the ice at Munson Pond, an ecological area, with endangered status, located south of downtown Kelowna.

"The flash of gold under the ice makes for a great picture, but unfortunately it's a story we're seeing repeated right across British Columbia, with schools of goldfish doing very well in ponds and small lakes…to the detriment of our local wildlife species.

"They would compete for food, potentially even eat small fish," Scott said.

Species originating in East Asia

According to B.C.'s Ministry of Environment, goldfish — also known as Carassius auratus — are an aquatic species originating in East Asian countries such as Hong Kong, Japan and South Korea. 

The ministry says pet owners have been intentionally releasing goldfish to water bodies, which could endanger local fish habitats because the species can rapidly reproduce even in extreme conditions.

Over the past decade, goldfish dumped by humans have been found in waterways across the province, including Dragon Lake near Quesnel, Lost Lake near Terrace, and Pinecrest Lake near Whistler.

Scott warns that it is illegal to dump invasive species like goldfish into local waterways in B.C. He said that the species are big omnivores that can drain food sources for native aquatic species.

"[Goldfish] could potentially be feeding on the small amphibians," she said. "They're also feeding on all the insect life in the pond…where the insects are the source of food for so many species that are both in the water but also outside of the water."

Can 'electrofishing' help?

Clare Greenberg, executive director of Sea to Sky Invasive Species Council, said goldfish also disturb sediment and increase water turbidity while feeding on other species. The province says water turbidity could harm the growth of aquatic plants.

While goldfish may be small creatures when contained in bowls or tanks in homes, they can grow to the size of a football in the wild, according to Greenberg.

She said once goldfish get established in lakes it's difficult to eradicate or even control their populations.

One method to control goldfish in natural settings is 'electrofishing,' which is attracting and stunning all the fish in a water body, and then selectively removing the goldfish and leaving the native fish in place.

But Scott doubts electrofishing is an effective way to eradicate the goldfish, given their very high reproduction rates.

"[Goldfish] females produce 40,000 to 50,000 eggs per year," she said. "You won't be eradicating the goldfish — you might just be reducing their population."

The B.C. government asks the public to report any sorts of invasive species via its mobile app, online form or email to [email protected].