From Sunday's Surrey Leader.
LEADER FILE PHOTO
The B.C.’s River Forecast Centre’s warning of near-record low levels on the Fraser River is leading calls for caution as the commercial fishery gears up for this year’s catch.
By Jeff Nagel
Black Press
Jul 14 2006
Salmon may face dangerously low and warm water levels when they migrate upriver this summer.
B.C.’s River Forecast Centre is warning of near-record low levels on the Fraser River upstream of Hope – as well as key tributaries where most sockeye salmon spawn.
Hydrologist Allan Chapman said it’s due to a low snowpack accumulation over the winter in the mid and upper Fraser watershed combined with record high temperatures in late May.
“The snow melt occurred very rapidly and very early,” Chapman said. “We’re looking at a one-year-in-50 type of event.”
There’s no problem in the lower Fraser – mountains around the Lower Mainland had healthy snowpacks.
But it’s a different story beyond Hope, where there’s no snow left in the mountains to sustain creeks and rivers through the summer.
Dry forest conditions and extremely low river levels are now being measured.
The Fraser near Prince George is near a record low, as well as tributaries like the McGregor and the Horsefly – which enters the Fraser near Quesnel and is a major sockeye producer.
The Fraser at Hope is 30 per cent below average levels.
The river conditions have sparked calls for caution as commercial fishermen gear up to take what they hope will be a big share of the estimated 17 million sockeye bound for the Fraser.
The fear is many salmon could perish because of stress from warm water conditions, as well as difficulty navigating obstacles because of low levels.
“It’s the temperature that’s the real issue,” said Craig Orr, of the Watershed Watch Salmon Society.
He said long exposure to warm rivers kill sockeye by allowing the growth of a parasite that attacks the kidneys.
“Every sockeye that goes back up the Fraser picks them up in the estuary, but they only become a problem at a certain thermal stress level on the fish,” Orr explained.
“The kidney parasites take over and shut down the kidneys and it’s game over after that for a lot of these fish.”
Orr said fishery managers must take added precautions to ensure enough sockeye reach their birth streams to spawn – and that may require tighter restrictions on the commercial fleet.
“We’ve got to account for more environmental conditions,” he said. “It’s not the bonanza it used to be in terms of harvesting 60 to 70 per cent of returning sockeye. We just can’t do that any more.”
Orr said research suggests unusually low summer river flows in western Canada may be a trend rather than an anomaly.
“We’re seeing a decrease in mean river flows in a lot of these river systems, probably because of climate change impacts,” he said.
Other threats on the horizon to salmon habitat may also need to be offset, he added.
Chief among them, Orr said, may be the major push now underway in the Interior to rapidly log vast swaths of forests attacked by the mountain pine beetle.
“I’ve been talking to several fisheries biologists who are very concerned about salvaging going on and that we’re going to see even greater changes in the flow of the Fraser in the next few years.”
There’s concern that accelerated logging to recover beetle-killed timber can cause even more rapid runoff, as well as threaten salmon streams with sedimentation.
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