Saturday » March 31 » 2007
Gluttonous harbour seals to get shock of their lives
Scientists hope electric current to keep seals away from dwindling salmon run
Judith Lavoie
Times Colonist
Friday, March 30, 2007
CREDIT: Times Colonist
An electrical field will be installed in the Puntledge River to protect the summer salmon run from a ravenous gang of harbour seals.
A gang of harbour seals near Courtenay, which has discovered the secret of a non-stop salmon buffet, is in for a shock.
About 20 seals in the Puntledge River have perfected a system of lying on their backs under a bridge so city lights illuminate young salmon as they come down the river, making for easy pickings.
“It’s incredible to see. They line up shoulder to shoulder on their backs, poking their noses up,” said Bruce Adkins, head of the Department of Fisheries and Oceans’ south coast habitat and enhancement branch.
But the night-time snacking is about to come to a sharp halt: DFO and the Pacific Salmon Commission plan to install an experimental underwater electrical field to convince the seals to stay away in order to protect a fragile run of summer chinook which, last year, was down to about 1,000 spawning fish.
The $35,000 feasibility study on the Puntledge will be closely watched by groups along the West Coast.
The salmon commission’s test fisheries on the Fraser River, designed to give data on species, origins and numbers of salmon, are “virtually useless” for several months every year because about 10 seals feed from the gillnet, said Jim Cave, the commission’s head of stock monitoring.
“If this works on the Puntledge, it could be used in other applications,” he said, adding that “a lot of money” is being spent in the U.S. on trying to keep sea lions in the Columbia River away from the salmon.
The system, built by a company called Smith-Root, will use underwater wires at the river’s edges to pulse out a current across the width the river.
It has been tested on two captive seals at Vancouver Aquarium so biologists and Smith-Root can ensure the electrical field will be enough to deter the seals, but not enough to harm them or the fish.
Aquarium veterinarian Dr. Marty Haulena, who supervised tests on the captive seals, said once the electrical field was turned on, dividing the pool, the seals decided not to swim across the area with the current.
“I guess the seal felt some sort of current. Maybe something like a tingle on his whiskers which suggested he didn’t want to go there,” he said.
“They didn’t react like they were jolted. One did a circle around looking at its rear end and then swam away.”
The seals did not appear to suffer any lingering effects and, within minutes of the electrical field being removed, swam the entire length of the pool, Cave added.
Installation on the Puntledge will be around mid-April and the length of the experiment will depend on its success. In previous years, the seals have been killed, something sports fishermen are once again calling for.
jlavoie@tc.canwest.com© Times Colonist
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