80
percent of sockeye salmon may die this year because of warmer waters.
Boiling point : Hot
water killing 50% of
|
The
Columbia River in Oregon and Washington is usually teaming with hundreds
of thousands of sockeye salmon this time of year, but warming waters have wiped
out nearly 50 percent of this year’s population – and it could get worse.
Although more than
507,000 sockeye salmon have migrated up the Columbia River this year, more than
250,000 have died, according to the Associated Press [1]. Reuters, meanwhile, put the
number at 235,000.
“We’ve never had
mortalities at this scale,” said Oregon Department of Fish and Wildlife fisheries
manager John North to Reuters.
In fact,
the bad news could get even worse : Up to 80 percent of the entire population
could ultimately die, Ritchie Graves of the National Oceanic and Atmospheric
Administration told the AP.
The
enormous mortality rate has been blamed on water temperatures reaching up to 76
degrees Fahrenheit (24.45 °C). Scientists say that water temperatures above 68
degrees (20 °C) can put severe stress on fish, since there is less dissolved
oxygen to be found in water at higher temperatures. This makes it hard for the salmon to breathe, an issue that
becomes especially serious since their metabolism also spikes under such
conditions, forcing them to burn off energy that would otherwise be saved for
later.
Additionally, hot water
can foster the growth of deadly pathogens that can infect the fish.
“The
water temperatures in the Columbia River are nearing lethal levels for salmon,
which is a little inconvenient if you’re a salmon trying to come into the Columbia River and migrate,” Teresa Scott, Washington Department
of Fish and Wildlife’s drought coordinator, said to ThinkProgress [2]. “It’s a matter of fish being caught in those
warm waters and not being able to deal with them.”
Contributing to the
warmer water is a combination of drought conditions on the West Coast and
higher than normal temperatures, as well as unusually low runoff from mountain
snowmelt. Snowmelt can
help keep rivers cool, but this year the Columbia River
reached 70 degrees (21.12 °C) in the middle of June, Reuters reported. It
doesn’t typically hit that level until mid-July.
In an attempt to help,
officials are unleashing cooler water from various reservoirs into the river to
keep temperatures at a more manageable level for the fish. Another option is
pulling the fish out of the river and trucking them to cooler waters.
Still, Scott said that
low snowmelts and high temperatures could be a continuing problem if the
climate keeps getting hotter.
“There’s no doubt on
the part of our climatologists that say that these are the kinds of conditions
that we will see in the future,” Scott told ThinkProgress. “We are mounting short term
responses this year, and anticipating a recovery from these conditions in the
near term, but certainly this is a wakeup call and a dress rehearsal for what
fishery managers years from now will be dealing with on a regular basis.” Source
NOTES :
[1] : Earth First Journal (with Associated Press)
[2] : Think Progress
See also : Dijital Journal
COMMENTAIRE :
Avant la fin du temps de grâce de l'Éternel, la Terre sera touchée du tiers de son contenu... le tiers de la nourriture possible des hommes sera détruit. (Bible)
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