https://www.cnn.com/2019/08/16/us/alaska-salmon-hot-water-trnd/index.html
[images and links in online article]
The water is so hot in Alaska it's killing large numbers of salmon
By Ryan Prior, CNN
Updated 7:23 AM ET, Sat August 17, 2019
(CNN)Alaska has been in the throes of an unprecedented heat wave this
summer, and the heat stress is killing salmon in large numbers.
Scientists have observed die-offs of several varieties of Alaskan
salmon, including sockeye, chum and pink salmon.
Stephanie Quinn-Davidson, director of the Yukon Inter-Tribal Fish
Commission, told CNN she took a group of scientists on an expedition
along Alaska's Koyokuk River at the end of July, after locals alerted
her to salmon die-offs on the stream.
She and the other scientists counted 850 dead unspawned salmon on that
expedition, although they estimated the total was likely four to 10
times larger.
They looked for signs of lesions, parasites and infections, but came up
empty. Nearly all the salmon they found had "beautiful eggs still inside
them," she said. Because the die-off coincided with the heat wave, they
concluded that heat stress was the cause of the mass deaths.
Quinn-Davidson said she'd been working as a scientist for eight years
and had "never heard of anything to this extent before."
"I'm not sure people expected how large a die-off we'd see on these
rivers," she said.
The heat wave is higher than climate change models predicted
The water temperatures have breaking records at the same time as the air
temperatures, according to Sue Mauger, the science director for the Cook
Inletkeeper.
Scientists have been tracking stream temperatures around the Cook Inlet,
located south of Anchorage, since 2002. They've never recorded a
temperature above 76 degrees Fahrenheit. Until now.
On July 7, a major salmon stream on the west side of the Cook Inlet
registered 81.7 degrees.
Mauger said she and her team published a study in 2016, creating models
outlining moderate and pessimistic projections for how climate change
would drive temperatures in Alaska's streams.
"2019 exceeded the value we expected for the worst-case scenario in
2069," she said.
Mauger said that the warm temperatures are affecting salmon in various
ways, depending on the stream.
"Physiologically, the fish can't get oxygen moving through their
bellies," Mauger said. In other places in the state, the salmon "didn't
have the energy to spawn and died with healthy eggs in their bellies."
Salmon under threat
Salmon populations are under stress from other angles as well.
Overfishing is threatening salmon further south in southwestern Canada
and northwestern Washington. Orca whales, which are themselves
endangered, feed on salmon.
With fewer salmon to eat, populations of orca whales have steadily
declined over the past decades.
And last week the Environmental Protection Agency told staff scientists
it would no longer oppose a mining project in Alaska that had the
potential to devastate one of the world's most valuable wild salmon
fisheries, just after President Trump met with Alaska's Gov. Mike Dunleavy.
But in other areas, things are looking up. "Salmon are very resilient.
They've overcome a lot," said Mary Catharine Martin, a spokeswoman for
the non-profit Salmon State.
Alaska's Bristol Bay, the largest sockeye salmon fishery in the world,
is annually seeing boom times for salmon returns, and in 2016 celebrated
the 2 billionth salmon caught in its waters, after more than a century
of commercial fishing.
"That's very good," she said. "Salmon have sustained the way of life of
the people of Alaska for thousands of years."
CNN's Alisha Ebrahimji contributed to this story.
=====================================
To subscribe, unsubscribe, turn vacation mode on or off,
or carry out other user-actions for this list, visit
https://www.freelists.org/list/keiths-list
Note: new climate change website is now in pre-launch
Visit https://www.10n10.ca/e/index.shtml