It all started in March, when a city councilor in Ottawa got a call: Thousands of dead goldfish had washed up on the banks of a pond in a city park. The city responded with a cleanup effort.
It wasn’t enough. Riley Brockington, the city councilor who represents the area around Celebration Park, in the Canadian capital city, recently received another call about the pond’s goldfish invasion.
“Sure enough, I sent the same city staff back and they confirmed there were approximately 1,000 live fish in the pond,” which collects storm-water runoff, Mr. Brockington said.
The city has a plan to collect the fish with nets and euthanize them, according to Ryan Polkinghorne, the city’s program manager for storm-water management and environmental monitoring.
Removing the fish now could prevent them from washing ashore dead again, Mr. Polkinghorne said in a statement. The fish that washed ashore in March, some 5,000 of them, died because of low oxygen in the pond, he said. Regulations in Ontario require all invasive fish captured in storm-water ponds to be euthanized.
The new efforts may still not be enough to rid the pond of goldfish. “They’re pretty hard to kill,” said Steven Cooke, a biology professor at Carleton University in Ottawa, “and that’s because they do well in places that have poor water quality.”
Professor Cooke added, “It’s hard to underfeed them, it’s hard to overfeed them.”
Goldfish are an invasive species, originally from Asia. They were once kept in fountains as decoration before becoming a popular pet for children.
They also breed rapidly. A female goldfish can produce 6,000 eggs and can reproduce more than once a year, he said. Without a large population of predators, goldfish will take over an ecosystem and push out native species, he said.
He also warned that heavy rainfall could help the goldfish escape the pond. “All of the sudden they get pushed out and now they’re in the river and then they get downstream into other areas,” said Professor Cooke, who says the latest fish estimate is most likely an undercount.
Mr. Polkinghorne said city officials did not know how the goldfish ended up in the pond at Celebration Park. Mr. Brockington’s theory is that someone dumped their pet fish there. (Professor Cooke said unwanted fish should be returned to the pet store instead.)
Once they’re established, the fish are, as Ottawa can attest, difficult to get rid of, as they can evade netting. Chemicals are an option, but that would wipe out all life in the pond and it would take a long time for such a method to be approved, Professor Cooke said.
“If I was a betting man, I would put my money on next fall them having to go out and attempt to do the same thing because they’ve spotted more goldfish,” he said.
Rylee Kirk reports on breaking news, trending topics and major developing stories for The Times.
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