number of sea lions at Bonneville Dam is below average and most are the larger
steller sea lions, not the California sea lions that have been showing up at
the dam each spring to feast on salmon and steelhead.
fact, all of the observed predation between Dec. 8, 2018 and Jan. 31, 2019 on
fish has been by steller sea lions and no observed predation has been by
California sea lions, according to the first 2019 monthly pinniped status
report released this year by the U.S. Army Corps of Engineers.
this period, just one chinook salmon, four coho salmon (in December), 11
steelhead and one white sturgeon were observed by the Corps being eaten by
pinnipeds in the dam’s tailrace, the report says, adding that these are raw
numbers of actually observed predation which don’t account for periods when
observations were not being made.
spike in the number of coho salmon passing Bonneville Dam in December raised
salmonid passage at the dam to above the 10-year average for the month, but
January’s passage of salmonids was below normal.
to the in-season nature of this update, “the estimates provided here are the
raw, unadjusted, and un-expanded estimates. Final (bounded) estimates will be
provided after the season has completed and the data have been reviewed and
analyzed,” the report says.
during the period Dec. 8 through Jan. 31, 11 “other” fish were taken. Those
include: 1 small mouth bass, four chum salmon (listed as threatened under the
federal Endangered Species Act), one walleye and five unidentified fish. A separate
category “unidentified” added 13 more fish for a total predation of 43 fish.
report, “January Update: Pinniped Abundance and Salmon Predation at Bonneville
Lock and Dam,” was released Jan. 31 by the Corps’ Fisheries Field Unit: http://pweb.crohms.org/tmt/documents/FPOM/2010/Task%20Groups/Task%20Group%20Pinnipeds/190131%20Bonneville%20Pinniped%20update.pdf
spring 2018, the last sea lion departed from the dam June 2, 2018, but the
first steller sea lion arrived back at the dam July 14 and some number of the
animals have been present at the dam ever since. The first California sea lion
arrived Nov. 5. The study says that steller sea lions arrived 14 days earlier
than in the previous year and their numbers have been increasing at a greater
sea lion average daily abundance during the study period was 7.9 animals (range
of 2 to 24 animals), lower than the 10-year average during the month of
January. The average daily abundance of California sea lions has been much
lower, calculated by the Corps at 0.04 animals (range of 0 to 1), also lower
than the 10-year average.
harbor seals have been seen at the dam since Jan. 24, 2018.
24 unique steller sea lions have been identified. However, the Corps says the
number of individually identifiable stellers based on brands and unique markers
is half that, at 12. “The number of individually identifiable pinnipeds is
difficult to estimate due to the limited branding effort for the SSL,” the
to the Corps’ final pinniped report for 2018, steelhead were hit hardest by
steller and California sea lions in the fall of 2017 and the spring of 2018,
but most of that predation was by a rising number of steller sea lions in the
spring and fall.
7.2 percent of the steelhead run from January through May 2018 was taken by the
predators and 6.8 percent of the winter steelhead run was taken November 2017
through March 2018 (pinnipeds took 11 percent of the steelhead run in 2009). Of
the winter and summer runs of steelhead, steller sea lions took 6.1 percent
while California sea lions took 1.1 percent.
the number of salmonids taken by pinnipeds during 2018 was lower than in 2017,
the number lost was still near the 10-year average, the Corps report says.
2018 annual report is at http://pweb.crohms.org/tmt/documents/FPOM/2010/Task%20Groups/Task%20Group%20Pinnipeds/2018%20Pinniped%20Annual%20Report.pdf
number of steller sea lions in the spring of 2018 was 4.7 percent higher than
in 2017 and 4.8 percent higher than the 10-year average. The number of
California sea lions dropped by 27.1 percent in 2018 from 2017 and by 23.9
percent of the 10-year average.
near record low runs of ESA-listed winter and summer steelhead and small run of
ESA-listed spring Chinook Salmon that passed Bonneville Dam this sampling
season had to swim past high numbers of SSLs, however numbers of CSLs are
slightly lower than past years,” the 2018 annual report says. “Our estimates
show that in general: CSL abundance and fish consumption are down, SSL
abundance and fish consumption are up, and the total number of salmonids killed
this year by both species of pinniped, although lower than previous years, is
similar to the ten year average.
documented increasing trends in White Sturgeon predation that are of concern,
and identified that ESA-listed winter steelhead are being impacted by prolonged
SSL presence and predation,” the annual report continued.
lions are protected under the federal Marine Mammal Protection Act. California
sea lions in the U.S. are not listed as endangered or threatened under the
federal Endangered Species Act. The most recent population estimate for the sea
lions in the U.S. was 296,750 animals in 2016.
that will allow the lethal removal of more California sea lions, as well as
steller sea lions, from the Columbia River was signed into law by President
Trump in December. The Endangered Salmon and Fisheries Predation Act amends the
existing Marine Mammal Protection Act of 1972 by giving more flexibility to
remove sea lions that prey upon threatened and endangered salmon and steelhead
in the Columbia River. The bill also lists white sturgeon as a protected
species. Oregon, Washington, Idaho and CRITFC have said they will apply for a
MMPA Sec. 120 permit to begin removing steller sea lions at Bonneville Dam.
addition, a MMPA Sec. 120 permit was given to the Oregon Department of Fish and
Wildlife last year to lethally remove up to 93 California sea lions from
Willamette Falls on the Willamette River near Portland in order to protect from
predation by the mammals the runs of wild winter Upper Willamette River
steelhead and spring chinook. ODFW has lethally removed five California sea
CBB, February 1, 2019, “ESA Winter Steelhead Impacted By Prolonged Steller Sea
Lion Presence At Bonneville Dam,” http://www.cbbulletin.com/442082.aspx
CBB, January 11, 2019, “With New Permit, Oregon Begins Lethally Removing Sea
Lions At Willamette Falls To Protect Steelhead,” http://www.cbbulletin.com/441999.aspx
CBB, December 14, 2018, “Legislation Awaiting President’s Signature Would Allow
Significant Increase In Killing Of Salmon-Eat,” http://www.cbbulletin.com/441918.aspx
CBB, November 20, 2018, “Oregon Plan To Euthanize Sea Lions At Willamette Falls
Approved By NOAA Fisheries,” http://www.cbbulletin.com/441816.aspx
CBB, March 16, 2018, “Corps Report: Pinniped Predation Consumed 4.7 Percent Of
Salmonids In 2017 In Bonneville Tailwater,” http://www.cbbulletin.com/440368.aspx
January 19, 2018, “West Coast California Sea Lion Population Has Rebounded;
Meets Marine Mammal Protection Act Goal,” http://www.cbbulletin.com/440111.aspx
December 1, 2017, “Recovery Of West Coast Marine Mammals Dramatically
Increasing Consumption Of Chinook Salmon,” http://www.cbbulletin.com/439896.aspx