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26th August 2021
EDITORS NOTE: This article is long. I will not post it all here, but you can go to the link at the bottom of the posting and read it in its entirely there.

‘It’s pretty dire’: Vancouver Island salmon under threat from climate change-induced droughts

As the island enters the most severe level of drought in the province, experts warn B.C. has much work to do to manage for watershed health in the midst of prolonged dry spells

By Braela Kwan
Aug. 20, 2021

This story is part of When in Drought, a series about threats to B.C.’s imperilled freshwater systems and the communities working to implement solutions.

Coho salmon were on track to have a good year in the Tsolum River, which merges with the Puntledge River near Courtenay, B.C., on the east coast of Vancouver Island.

Then came the heatwave and drought.

“The numbers were so good before the heat came. It was a particularly good year,” says biologist Caroline Heim, the program coordinator of the Tsolum River Restoration Society.

Between June 26 and 29, the community restoration group observed coho fry swarming in massive numbers at cool groundwater upwelling “refugia” sites where water temperatures were up to 15 C cooler than the general river temperature — which climbed as high as 29 C during that time. Within that period — during which the hottest temperature ever in Canada was recorded in Lytton, B.C. — the group also observed a significant coho die-off.

“​​It’s hard to quantify how many died. A conservative estimate would be at least half, but probably much more than that,” says Heim. “It’s pretty dire.”

The Tsolum River is part of the East Vancouver Island Basin, a region experiencing a severe drought caused by low spring precipitation and record-high temperatures.

On Friday, the province increased the drought severity on Vancouver Island to level five, the most intense drought rating possible. Under level five drought conditions, adverse impacts on socio-economic or ecosystem values are “almost guaranteed,” according to the B.C. drought information portal.

The province declared significant drought conditions across B.C. on July 9, noting that “adverse impacts on fish have been observed” due to elevated water temperatures, low flow conditions and reduced water availability. The public is being urged to conserve water.

Since the initial June to July heatwave shocked the Pacific Northwest, Heim says the Tsolum River Restoration Society has observed significantly fewer fish in the river, especially in its lower portions. Many of the remaining coho, which survived the heat wave, are suffering from diseases and fin rot as a result of heat stress, she adds.

Now that pink salmon are beginning to run in the Tsolum, Heim says the restoration group will monitor for signs of early fatalities, which may occur before the fish get a chance to spawn, as brutal regional heat and drought conditions persist.

Such tough conditions aren’t limited to the Tsolum, however.

On eastern Vancouver Island, watersheds of special concern in the ongoing drought include Sandhill Creek, Koksilah River, Chemainus River, Millstone River, Tsolum River, Black Creek as well as areas in the Gulf Islands.

Decreasing flows, losing habitat and warming Vancouver Island waters

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