Electronic seal fence showing mixed results

Marcel Tetrault
Comox Valley Echo

Friday, May 23, 2008

Testing continues on the electronic seal deterrent in the Puntledge River and the results so far are mixed.

Gary Tacconga, salmon enhancement operations manager for Vancouver Island, said that fisheries staff have been testing various configurations to see what is most effective at dissuading seals from snacking on salmon.

Testing began at the end of April and the length of the electronic pulse emitted by the array is varied between one thousandth of a second and five thousandths of a second.

"We found, as we kind of expected, that it was not effective at all at the low end," said Tacconga. "We were starting to see seals stop as we got to the upper end of that range, but not 100 per cent.

"We were still seeing good numbers of seals moving through. They would challenge it."

There was also an issue with one section of the electronic array being shorted out, likely by metal in the streambed.

"The seals were smart enough to find out where it was grounding out," said Tacconga. "You could see them moving through that one little weak spot in the field."

The first configuration of cables along the riverbed was considered ineffective and so testing began on a second configuration on May 14.

With the new design, Tacconga said that about one third of seals are turned away with two millisecond pulses. With three millisecond pulses, about half turn away.

"At four milliseconds, it seemed to stop virtually everything," he said. "But the other thing we noticed, while most of the animals seemed to detect it, turn around and head back downstream, we had a couple that actually charged through.

"They seemed to be having some difficulty with the electrical current -- you could see some involuntary muscular reaction in the animals and then they would carry on."

Due to the seal's reactions the pulse lengths were turned back down and a veterinarian arrived yesterday (Thursday) to determine whether or not four millisecond pulses are damaging the seals.

"If he's confident with the four millisecond setting, then we'll resume operations at that level," said Tacconga.

Puntledge River Restoration Committee co-chair Larry Peterson witnessed the array in action at the three-millisecond pulse length on Tuesday night. Peterson has been calling for a cull of the seals and he was not impressed with the results he witnessed.

"By about quarter to 10, it looked like just an absolute wall of death," he said. "The seals were just creating a wall."

Right now, it is mostly juvenile chum salmon that are escaping the river. That run is strong and so can withstand some seal predation.

But the threatened run of summer chinook, built up from as few as 150 fish in the mid-1990s to as many as 3,000 a few years ago and now back down to around 1,000 fish, will soon begin the journey to the ocean and become targets for the seals.

That run, as well as the coho, cutthroat trout and steelhead in the river are of particular concern to Peterson.

"Unfortunately, as hateful as it is, I have to say those (seals) need to be lethally eliminated ... and there are upwards of 30 of them, we think," he said. "They're dogs in the water. They're smart and they make adjustments."

There are currently no plans for a seal cull, although there is a licence to kill seals that travel as far up the river as the hatchery. Peterson said that the time window for a cull this year is rapidly closing.

"Once again, we're just so late in the game," he said. "They've been stalling us for about three years now and, with the electrical array and so on and so forth probably they can string us along for another couple.

"In the meantime ... a fish run is decimated and further endangered. It's bizarre."

© Comox Valley Echo 2008

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