Goldfish genocide

Goldfish genocide OK’d by conservation authority
Richard Leitner, The Hamilton Mountain News

Tadpoles potential ‘collateral damage’ in bid to preserve salamanders’ habitat

Despite some concerns about the “unfavourable optics,” the Hamilton Conservation Authority will use a natural pesticide to kill goldfish in two Dundas Valley ponds that are home to nationally and provincially threatened Jefferson salamanders.
Directors unanimously approved the use of rotenone, derived from the roots of tropical plants in the bean family, after hearing the ravenous fishes’ exploding population is putting the salamanders’ breeding habitat at risk.
The fish were apparently dumped in the ponds by people who wanted to breed them for use in backyard ponds and, in the case of the McCormack Pond in the Governor’s Road Conservation Area, now number an estimated 30,000 — up from about 40 when first noticed in 2005.
A similar problem looms at the pond by the former Merrick Field Centre in Ancaster – described as the salamanders’ hottest breeding area in the valley – where fish were introduced last year and a new stock was discovered in July.
Authority ecologist Shari Faulkenham said the goldfish devour anything they can fit in their mouths, including the eggs of the salamanders, which are in the ponds from late March until maturity in late August.
Other efforts to remove the fish, including using a large seine net and electrical charges, have failed, she said.
“I’m afraid we’ll reach a breaking point where we’ll no longer have Jefferson salamanders returning to the pond” because of unsuccessful breeding, she said.
“Basically, we have an area where they lay their eggs, these eggs hatch and they live in that pond for a number of months, and then we have probably 20 or 30 thousand goldfish that are gobbling them up.”
Ms. Faulkenham said rotenone is relatively harmless to other species but effective on fish because it is absorbed into the bloodstream through their gills and initiates a cellular process that makes oxygen toxic.
While the plan is to apply it in late summer or early fall, when the salamanders are out of the ponds, she said rotenone may also kill some tadpoles of green frogs, which take two years to mature and will be the lone other gilled species present at that time.
“That’s the only potential downfall,” she said, noting the Ministry of Natural Resources, Hamilton Naturalists Club and Jefferson Salamander Recovery Team support using rotenone in this case.
“Even though tadpoles aren’t as susceptible to rotenone as fish, there may be some collateral damage as a result. Luckily, green frogs aren’t a rare species. They can quickly repopulate.”
Although supporting the plan, Councillor Tom Jackson said he is concerned about how the public will react.
“Just on the surface, the optics of pesticide use on a pond isn’t the most favourable, in my humble opinion,” he said. “Just as a layman, I’m struggling with this.”
But chair Chris Firth-Eagland said he’s seen the carp-like fishes’ impact on the McCormack pond first hand as a neighbour on an adjacent farm and action is necessary.
Once pristine, dark and mysterious, with duckweed in the summer, the spring-fed pond is now “a mud puddle,” he said.
“It’s absolutely destroyed. There’s no duckweed. There’s no vegetation. There’s nothing but dark, coffee-coloured, muddy water. We may be too late,” he said. “The entire ecosystem has been completely flipped around.”
Mr. Firth-Eagland said he believes he stumbled upon the people who stocked the pond during a midnight stroll this spring, when he encountered three men with powerful head-mounted flashlights, large fishing nets and bags of fish.
He said he was carrying a talking stick and “waltzed the men down to their car,” but failed to get their licence plate number so they could be charged.
“These fish were put purposely there to create an illegal commercial opportunity,” he said. “They weren’t dumped out of some kid’s fish tank at home because they felt sorry for the fish.”
Ms. Faulkenham said if breeding the fish for sale were indeed the intent, doing so is “absolutely impossible” in a natural setting because of the genetic manipulation needed to maintain the ornamental fishes’ colour.
“Within one generation, they’re all brown,” she said. “What they did was absolutely pointless.”
Before proceeding with the eradication plan, Ms. Faulkenham said the authority must obtain approval from a provincial pesticide advisory committee. Sandbagging to prevent outflow from the ponds may preclude the need for additional permits, she said.
Once dead, the goldfish will be removed and either buried or sent to a dump, she added.


Rick