(PORTLAND, OR) -- Sometimes
being underwater is a good thing, especially for Columbia River salmon nests,
called redds. This fall, federal agencies have increased Columbia River flows
below Bonneville Lock and Dam to ensure the redds of spawning chum salmon stay
covered with water. The agencies have conducted these chum operations every
fall since 2000.
Beginning
in November, the U.S. Army Corps of Engineers holds the Columbia River below
Bonneville Dam to between 11.5 and 13 feet above sea level to ensure chum can
spawn at the mouth of Hamilton Creek in the Columbia River Gorge. For chum
operations to occur, water is released from reservoirs as far away as Hungry
Horse and Libby dams in Montana, more than 850 river-miles upriver from
Bonneville Dam. The water is then captured and released as needed to keep the
redds underwater.
“Chum
are listed under the federal Endangered Species Act and they’re an important
part of the ecosystem,” says Scott Armentrout, BPA vice president of
Environment Fish and Wildlife. “This operation is just one of the things
we do with our federal partners to support this critical species.”
The
annual run of Columbia River chum salmon historically numbered more than 1
million. However, habitat loss, harvest, and other factors caused their numbers
to plummet during the last century to a low of just a few thousand fish
returning to the river each year. An important ecological species and food for
mammals such as whales, the federal government listed Columbia River chum as
threatened under the Endangered Species Act in 1999.
Called
“dog” salmon because of their canine-like teeth, chum are the last salmon of
the year to return to the Columbia to spawn, and their young are the first to
leave for the ocean in the spring. Chum salmon generally spawn in the lower
part of the Columbia River below Bonneville Dam in areas where warm groundwater pushes up through gravel. The warm water then quickly incubates their
eggs.
The
Bonneville Power Administration has funded two hatchery programs and
constructed new spawning habitat for chum in several areas of the lower
Columbia River. These efforts appear to be showing signs of success: More than
45,000 chum returned to the Columbia in 2016 and scientists say 2019 shows
signs of a good return as well.
