Seals triumphant in battle with electronic deterrent device

Marcel Tetrault
Comox Valley Echo

Friday, June 06, 2008

CREDIT:
DFO officials removed a seal deterrent electric fence out of the Puntledge River under the Fifth Street Bridge Thursday after an experiment to reduce seal predation on salmon stocks failed.

The seal deterrent device installed in the Puntledge to stop seals from slurping up salmon has been removed.

The device was taken out of the river yesterday (Thursday) morning as testing appears to have shown that it was not as effective as had been hoped at keeping the seals out of the upper portion of the river.

"We've tested both of the electrical array designs," said Gary Taccogna, DFO salmon enhancement program manager for the South Coast.

"The most effective array design, we're still only seeing about 70 per cent of the seals that approach the thing actually turn around."

Testing also determined that the array did not appear to have any effect on juvenile salmon leaving the river but that it does have some effect on adult salmon returning to spawn. Both of those results were expected, said Taccogna.

"We had 14 (adult salmon) show up on the ... monitor," he said. "They all basically hit the array area and slow up or stop. Forty per cent for sure hit the array, turned around and went back downstream, which is not what we want to see happen."

The removal of the deterrent device does not necessarily mean the end of its consideration as a possible tool in the battle against the Puntledge's seal population, but it will not return to the water this year.

Results in California, said Taccogna, have shown that increasing the number of electrical pulses each second might be more successful at deterring seals. They might also consider widening the array.

"Probably all (the seals) are feeling ... is one pulse as they transit through this 20-foot section," he said.

"It's obviously not enough of a deterrent if they can sort of grin and bear it through one pulse. We may want to go with a higher setting, as high as five (pulses) per second."

But those trials are in the future and there is still the immediate problem of seals predating on juvenile fish and putting the vulnerable summer Chinook salmon run at risk.

"A cull is certainly not out of the question," said Taccogna. "But there has to be some benchmark set, that everybody can agree on ... where we might need to make more drastic action that might include a cull."

Getting agreement with respect to how low the salmon numbers must go before a cull is called is "a pretty significant piece of work" that Taccogna said he'd like to see completed this year. That would push any possible cull out until next year.

"I can't see a cull happening this year, I would think at the earliest it would probably be next spring."

The real issues on the Puntledge, said Taccogna, stem from the flooding of the summer Chinooks traditional spawning territory between the Comox dam and the diversion dam further downriver as well as the lack of suitable fish habitat in the watershed.

"That's what has driven the stock down to such low levels of abundance that we now have to worry about things like seals in the lower river," he said. "Basically the salmon ... have really got no place to hide."

Work like installing spawning platforms and complexing the river has been ongoing for several years.

"There are a number of things that are going on in the background (and) the hope is that it will also benefit the Chinook and turn the population around," said Taccogna. "It's probably a couple of years yet until we see the results of that."

© Comox Valley Echo 2008

http://www.canada.com/comoxvalleyecho/news/story.html?id=cfacd8ad-4b82-45bf-aea5-138a4a95027f

Submitted by Char Olson,
Courtenay, BC