From cast-off pets to a pond catastrophe: P.E.I. naturalists dealing with goldfish sightings

A central P.E.I. watershed group and the provincial Department of Forests, Fish and Wildlife are raising concerns about sightings of more goldfish in Hardy's Pond.

In 2021, teams removed hundreds of goldfish from the 9.2-hectare pond in the Union Road area, north of Charlottetown. Now they're once more getting calls from the public flagging that the population appears to be rebounding, with some even spotting schools of the brightly coloured fish.

"We've seen quite a few small ones this year even, so that means they've already been reproducing," said Raena Parent with the Winter River-Tracadie Bay Watershed Association.

"Someone told me they've seen about 75, so I'm guessing we're at least at 100."

That's 100 too many, she said. Goldfish are known to be an invasive species that thrives in calm bodies of fresh water like Hardy's Pond. They can carry diseases, parasites, viruses or bacteria, and that's not good for the native species in the area.

"There's a list of reasons why we don't want goldfish around here to begin with," said Parent.

"They'll eat anything ... the vegetation on the ground in the pond, they'll eat other fish, fish eggs, insects, their larvae. The biggest issue, I have to say, would be they're bottom feeders."

Hardy's Pond has been dredged in the past, but Parent said there is still a decent amount of silt in it. When bottom-feeding fish rummage around, all that silt gets stirred up and particles end up floating around in the water.

"It's hard for the light to penetrate, which can then inhibit plant growth. And that then takes away from habitat, what other species need to eat and so on," she said. "So it's very problematic."

P.E.I.'s freshwater fisheries biologist, Rosie MacFarlane, suspects the fish population started off as cast-off pets from home aquariums or backyard ponds.

Maybe the pond overflows and sends the fish into a nearby sewer system or stream, or maybe an owner decides they can no longer care for the fish and thinks releasing them is best.

Unfortunately, MacFarlane said, that's the wrong choice.

"People need to think long and hard before they purchase one of these fish," she warned.

"We would encourage anyone with goldfish that they no longer want to try and rehome [them]... If you can't do that, you should humanely euthanize those fish because we really don't want them in our rivers and ponds."

And once they get in, it's tricky to get them out.

"These things are pretty prolific and they can grow quite big and they can live a long time," said MacFarlane. "It is a serious issue — not just in P.E.I. These things are invasive everywhere."

The good news: MacFarlane said the goldfish appear to be concentrated in the pond and not spreading through the Winter River, which has some of the best trout fishing on the Island.

Last week alone, her crew found roughly a dozen specimens. The majority were just below the Hardy's Pond dam and one was located further downstream.

"I still think there's a lot in the pond itself, but we are going to look at ways that we can do better assessment on that and maybe figure out some management measures down the road," said MacFarlane.

As for Parent, she said the watershed is keeping a close eye on the situation too, and has been tackling the surrounding streams while the next steps for the pond itself are sorted out.

"These fish can live for decades... You have to make sure that you're prepared to handle the number, how large they get, and just how much they need to eat," she said.

"Because as we can see here, they start to populate and grow and take over an area."