Hunt on to unmask the mass killer of Valens Lake carp
Testing begins to see if herpes wiped out hundreds of fish
THEY SAY NOT to speak ill of the dead, but the discovery of rotting carp at Valens Lake is spawning tentative celebration among fans of the local fishery.
Hundreds of the large invaders turned up dead at the conservation area near Puslinch recently, leaving ecologists to speculate if the destructive carp have a virus called koi herpes.
“This virus does only strike carp ... and does not pose a risk to people,” Lisa Burnside, chief administrative officer of the Hamilton Conservation Authority, said Monday after surveying the lake.
It’s safe to eat and handle infected carp, Burnside said.
The Ministry of Natural Resources is helping the conservation authority with testing to determine if koi herpes is indeed the killer.
“Fish die-offs can occur for any number of reasons, including natural events, chemical spills, water quality issues, and disease,” ministry spokesperson Jolanta Kowalski said. “It’s too early to speculate on a cause.”
Koi herpes has been known to wipe out carp in southern Ontario waters such as Chemong Lake, Lake Simcoe, Otonabee River, Rice Lake, Lake Scugog and Pigeon Lake.
“Fish die-offs can occur for any number of reasons, including natural events, chemical spills, water quality issues, and disease.” JOLANTA KOWALSKI MNR spokesperson
The virus, which also affects koi and goldfish, was first found in 1999 in the United States and spread to Ontario through the hobby fish trade, the ministry notes.
Fish are most vulnerable to the virus in a crowded habitat, while spawning and in water that’s between 18 C and 28 C.
The Royal Botanical Gardens’ fishway between Hamilton Harbour and Cootes Paradise is meant to keep carp, an invasive species, out of the latter.
So, could infecting the harbour carp with koi herpes render the fish fence obsolete?
“That’s in interesting question,” Burnside said with a chuckle, wondering about the ethics of introducing a virus on purpose to kill a fish population.
“I think that would have to be done very, very carefully. I would just worry about unintended consequences.”
Carp have been in Valens Lake since at least the late 1980s, said Gord Costie, who started working there in 1988.
They could have entered the lake — a reservoir that was flooded in 1967 — by accident via anglers’ bait buckets during outings for fish that were stocked
there, Costie speculates.
The carp tend to stir up sediment in the lake, potentially affecting the spawning grounds of other fish, such as largemouth bass, northern pike, bluegill, black crappie and yellow perch, said Costie, director of conservation area services.
“They’re big, full-sized carp. Nothing would be bothering them.”
Costie said it’s too early to forecast how the deadly virus could affect crowded-out locals, but some are already casting lines of hopeful speculation.
“There’s a number of people
out there that are interested to see how this plays out; it potentially could play out positively for the fishery.”
Burnside said specimens were taken to a lab in Guelph for testing. She expects results in a day or two.
In the meantime, staff are clearing the lake of the unsightly and stinky dead.
As of Monday afternoon, about 200 carcasses had been netted, Burnside said. “We’re making some progress.”