to the 1940s, as many as half a million to one million Columbia River chum
salmon returned to the Columbia River to spawn as far up the river as Celilo
the loss of habitat and overfishing, the total population in the Columbia River
has dropped to 1,000 to 10,000 fish and 14 of the 17 evolutionary significant
units are now considered at a high risk of extinction or extirpated, according
to Todd Hillson, lower Columbia River chum salmon program leader at the
Washington Department of Fish and Wildlife. He spoke Tuesday, July 11, at a
meeting of the Northwest Power and Conservation Council’s Fish and Wildlife
Committee in Vancouver, Washington.
other three ESUs – Grays River, Washougal and lower Gorge populations – are
considered to be at low to moderate risk of extinction.
decline of chum salmon began in the 1940s and is due to the loss, degradation
and access to spawning habitat, changes in the estuary ecology and habitat,
altered mainstem and tributary hydrology – much of that due to the addition of
Bonneville Dam that flooded the salmon’s spawning areas – and overharvest.
we built our towns on the lower end of the river, that was their habitat,”
Hillson said of the chum.
Columbia River Chum Salmon were listed for protection under the Endangered
Species Act in 1999. In 2004 the Lower Columbia Fish Recovery Board developed a
plan for their recovery as well as for other ESA-listed salmon as part of the
Northwest Power and Planning Council’s Subbasin Plan (the NPPC is now the
Northwest Power and Conservation Council). The LCFRB updated the recovery plan
in 2010, and NOAA finalized the federal recovery plan in 2013, according to a July
5 Fish and Wildlife staff memo (https://www.nwcouncil.org/media/7491182/f1.pdf).
much as half of the up to 1 million fish that once spawned in the river were
harvested, but harvest has now been completely stopped for both hatchery and
wild chum, although there is some incidental take of chum, but the limit on the
incidental take harvest is set at less than 5 percent of the projected run size each year.
of the chum spawning and incubation habitat was in off-channel or braided parts
of the river, Hillson said. That habitat, which results in a higher survival
for the fish, is needed especially when ocean conditions are poor. But
off-channel habitat was typically found in the lower river and has since been
limited by agriculture, dikes, levees and the growth of human populations.
prior to heading to the ocean is extremely important for chum fry. They are
small (30 – 40 millimeters, which is 1.18 – 1.57 inches), compared to chinook
fry that are about 160 mm (6.3 inches), and once they hatch and emerge, Hillson
said, they move out of the off-channel areas and head straight to the ocean.
that size, they are food for everything,” he said. Once in the ocean, survival
is typically less than one-half of a percent. “With this low marine survival,
freshwater survival rates must be high.”
hatcheries have helped reduce the extinction risk. About 175,000 fry have been
released into the Grays River basin in Washington across the lower Columbia
River from Astoria. And about 45,000 fry have been released into Duncan Creek
downstream of Bonneville Dam.
addition, Duncan Creek spawning channels were constructed in 2001 and upgraded
in 2008 and 2011, as well as spawning channels in Hamilton Creek in the 1980s,
also near Bonneville Dam. That habitat was upgraded in 2011.
a result, egg to fry survival in the off-channel sites is improving: Duncan
Creek averages about 54 percent and Hamilton Creek about 48 percent. The Grays
River channel, which is not an off-channel site, has a survival rate of about
overall, how is recovery of Columbia River chum coming?
the upper Gorge population, the spawning goal for delisting of the ESU is 900
fish. The 2016 spawning count from fish that migrated from the river in 2012
was 115 fish, which has been about the average number of spawners since 2002.
lower Gorge population with a delisting goal of 2,000 spawners is “not doing
badly and are on a positive,” Hillson said. “Eight out of 15 years has been
above the delisting goal.” Some 3,378 chum spawned in 2016 near Bonneville Dam.
of the lower Gorge population spawns in lower reaches of that area near
Washougal, Washington downstream to the I-205 Bridge that spans the Columbia
River in east Portland. With a delisting goal of 1,300 fish for this section of
river, last year’s return of adults to spawn tallied 3,120 fish.
River has the strongest population, Hillson said, and has a population that has
returned in numbers far above the river basin’s delisting goal for 15 years in
a row. The delisting goal is 1,600 spawners, but the actual return last year
(2016) was 12,325 fish, the strongest return of all 15 years. “That’s a big
rebound,” Hillson said.
good news is that together, the Grays, Washougal and Gorge population returns
in 2016 totaled 18,823 fish. The bad
news is that the persistence probability for recovery continues to be very low
for most ESUs.
quality and quantity of spawning and incubation habitat continues to be a
strong limiting factor for recovery in these other areas, such as at Skomakawa,
the East Fork of the Lewis River, and the Cowlitz River in Washington, and the
Sandy River in Oregon, among many others.
recovery will come with creating better habitat along with supplementation
hatcheries and reintroduction where needed, Hillson said.