The pinniped dynamics
appear to have changed a bit this spring with Steller sea
lions an ever-growing presence, though California sea lions
remain ever relentless in their pursuit of spawning salmon in
the tailrace of the Columbia River's Bonneville Dam, according
to preliminary data compiled by U.S. Army Corps of Engineers
A total of 63 different pinnipeds were counted
below the dam on April 16, a new one-day record high since
researchers began monitoring sea lion behaviors and eating
habits in 2002. That number included 17 Stellers, also a
record count over the course of the ongoing study.
In past years the two sea lion species have preyed almost
exclusively on different fish stocks, California sea lions on
salmon and steelhead and Stellers on white sturgeon. But early
results this year show some change.
California sea lions have been observed taking nine
sturgeon so far this year, as compared to six total in the
previous years of the study, according to a weekly status
report prepared by researchers Robert Stansell, Sean Tackley
and Karrie Gibbons. Their reports can be found at:
"There has been a noticeable increase in the number of
observations of Steller sea lions stealing salmon caught by
California sea lions as well as what appears to be direct
catches themselves, which may account for the slowing of
sturgeon taken over the past few weeks," the report says.
The take has slowed, but the preliminary data indicates the
sea lions have already nearly doubled last year's record total
with sea lions observed dining on 605 sturgeon, including at
least 21 fish that were larger than 5 feet long. The report
stresses that the data is preliminary and could change after
post-season analysis and proofing.
The salmon take is also on pace to break last year's total.
Observers tallied 3,859 salmonids being taken by sea lions in
2007, 4.2 percent of the total passing the dam. The sea lions
have over the course of the study begun arriving at the dam in
midwinter and for the most left the Columbia by the end of May
after the upriver spring chinook salmon run has petered out.
The chinook run includes Snake River and Upper Columbia stocks
that are listed under the Endangered Species Act.
From Jan. 11 through April 20 researchers have seen sea
lions consume 1,791 chinook and 258 steelhead, with the peaks
of the upriver run likely yet to arrive. Another 541
unidentified fish have been taken below the dam.
Thus far the researchers estimate they have seen 55
different California sea lions at the dam, which is 146 river
miles from the Pacific Ocean. They are now the target of a
removal effort launched Thursday by the Oregon and Washington
departments of fish and wildlife. Animals will be captured and
shipped to zoos and aquariums as an attempt to reduce their
impact on listed salmon stocks.
Of the California sea lions seen at the dam over the course
of the season (58 individuals), 31 are on the list of animals
targeted for removal. Each has been seen consuming salmon at
the dam and ignored efforts scare them away.
The Stellers, on the other hand, are ESA listed too and
thus largely untouchable. For the third year in a row the
states and Corps have mounted a hazing effort from the dam and
from boats to discourage sea lion predation. But the firing of
seal bombs, cracker shells and other scare tactics have been
"They can be chased out of the tailrace area," Stansell
said. But they never stray too far from the prime feeding
"They're getting very comfortable," he said of the Stellers.
A few of the sea lions apparently are slipping past
Bonneville, perhaps through its navigation lock when barges
are moved up and down the river.
"“There have been several reported sightings, from reliable
sources, in the Bonneville Pool, so there are likely one or
more sea lions present," said Stuart Ellis, a Columbia River
Inter-Tribal Fish Commission fishery biologist.
Tribal fisherman Robert Brigham of the Umatilla Reservation
said he spotted a sea lion on Monday near the boat launch at
the Cascade Locks in lieu fishing site.
"“It was swimming around, latching onto fish," he said.
“Seagulls were eating what was left over.
And then on Wednesday, Brigham said, a sea lion was
photographed "right along our nets."
Brigham said Warm Springs fishermen last week saw a sea
lion above Starvation Creek on the Washington side and there
have been sightings above Hood River near Stanley Rock.
Information on sea lion presence in Zone 6 will be useful
in the ongoing efforts to remove sea lions below Bonneville,
Ellis said. Fishermen are being asked to record the date, time
and location of sea lions they spot, as well as what the sea
lion is doing. Fishermen also are asked to note if the sea
lion has distinguishing marks or brands.
"If a sea lion is hauled out, we would like to know where
the haul-out site is," Ellis said. "We are also very
interested in getting photographs of sea lions."
If sea lions are spotted around the tribal fishing gear, or
interfering with tribal fisheries, fishermen may attempt to
chase away the sea lion using slingshots, fireworks, other
noise makers, rocks, etc.
But under federal law, Ellis said, it is not legal for
anyone, including tribal fishermen, to do anything that might
injure or kill a sea lion.
If fishermen see a sea lion, they should report it to Ellis
at 503-731-1312 or firstname.lastname@example.org, or they can report it to
Columbia River Inter-Tribal Fish Enforcement at 800-487-3474.