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As Spring Chinook Arrive, Steller Sea Lion Presence
at Bonneville Dam Breaks Single Day Record

by Staff
Columbia Basin Bulletin, May 18, 2018

Ted Walsey, fishery technician for Columbia River Inner Tribal Fish Commission, fires a cracker shell towards a sea lion, during routine hazing on the Columbia River near the Bonneville Dam (Ariane Kunze / Columbian) The number of Steller sea lions observed in the Bonneville Dam tailrace set an all-time one-day record May 7 of 66 sea lions. The previous record of 62 was set last year.

Sea lion numbers, both Steller and California sea lions, have increased since the U.S. Army Corps of Engineers first reported this year on their presence in an April 12 abundance report. The latest pinniped abundance information is from the third bi-weekly report, released May 12.

While California sea lion abundance is below average, Steller sea lions are far above the 10-year average (2008 - 2017) in numbers, the report says. The average daily count of Steller sea lions was 51.5 during the reporting period April 26 to May 10, while the average daily count of California sea lions, which a couple of years ago outnumbered Steller sea lions at the dam, is 10.1. No harbor seals have been observed since January 24, 2018, although three were seen by Corps observers between Jan. 1 and Jan. 24.

The first report of the year showed an average daily abundance of Steller sea lions of 7.7 and 0.4 California sea lions. The second report, released April 26 reported an average daily abundance of Stellers of 26.8 and California sea lions of 4.3.

During the reporting period that began April 10, the Corps has documented 27 SSL and 37 CSL as uniquely identifiable individuals. All uniquely identifiable sea lions have been documented near Bonneville Dam in previous years, except one CSL which was branded May 9, 2018. The low number of individually identifiable SSL is due to the limited branding effort for the species.

The "Bi-weekly Update: Pinniped Abundance and Salmon Predation at Bonneville Lock and Dam" summarizes the observed predation and deterrent activities at Bonneville Dam. Observations will continue through May 31st with a final report to follow in June.

The first 2018 bi-weekly report, dated April 12, 2018 and covering the period from January 1 to April 11 is at here. The second report, dated April 26 and covering the period from April 11 to April 25 is here.

The report was prepared by Kyle Tidwell of the Corps' Fisheries Field Unit.

The rise in the number of predatory sea lions at the dam corresponded with late arrival of spring chinook arriving at the dam's tailrace, the report says.

"From 26 April to 10 May, 2018, a total of 611 Chinook salmon, 26 Steelhead and five White Sturgeon (Acipenser transmontanus) have been documented being killed by pinnipeds," the report says. "Of the 718 recorded predation events, SSL account for 82 percent of them." Predation also includes 10 other types of fish and 67 unknown species of fish.

Steller sea lions took 515 spring chinook, 21 steelhead, 5 white sturgeon, one lamprey, 8 other and 54 unknown species.

California sea lions took 96 chinook, 5 steelhead and 13 unknown species.

The numbers are up from the second pinniped report (April 11 to April 25) which reported for the period a total of 69 salmon, 15 steelhead and 24 white sturgeon killed by pinnipeds.

A total 5,384 salmonids were eaten by sea lions in the dam's tailwater in 2017. That was 4.7 percent of the entire runs of spring chinook and summer/winter steelhead that passed the dam between Jan. 10 and June 2, 2017, according to the Corps' 2017 final pinniped report.

The number of salmonids taken by sea lions in 2017 was still far below the 2016 total of 9,525 or the 2015 total of 10,859. However, the sizes of the spring chinook and steelhead runs were much smaller in 2017, so the percentage of the run consumed by sea lions remained largely the same.

Sea lions consumed 4.5 percent of spring chinook, a total of 4,951, and 9 percent of summer and winter steelhead (322 fish) in 2017.

Although Steller sea lions, once listed under the federal Endangered Species Act as threatened in 1990 and endangered in 1997, were delisted in 2013. Both Steller and California sea lions continue to be protected under the Marine Mammal Protection Act, but California sea lions care being euthanized at Bonneville Dam under a Section 20 permit from NOAA Fisheries.

During the week of April 9, some five California sea lions on the list for removal were trapped and euthanized at the dam. Five more were taken the week of April 16 and the week of April 23, and four were trapped and euthanized the week of April 30. Some 24 California sea lions were identified, marked, trapped and euthanized last year. More than 190 California sea lions have been trapped during the period 2008 - 2018: 15 were placed in permanent captivity, seven died in accidents incidental to trapping and the remainder were euthanized.

A bill introduced in Congress by two members of the Northwest's congressional delegation one year ago in April would make it easier for tribes and states to obtain permits to remove sea lions from the Bonneville Dam tailrace.

The Endangered Salmon and Fisheries Predation Prevention Act would allow both tribes and states to remove sea lions near Bonneville Dam. While the removal program as proposed by the bill would still be subject to and limited by Section 120 of the Marine Mammal Protection Act, it would more closely be brought into alignment with the Endangered Species Act, according to the Columbia River Inter-Tribal Fish Commission.

Introduced by U.S. Reps. Jaime Herrera Beutler (R-WA) and Kurt Schrader (D-OR), the bill would allow Northwest states and tribes to potentially obtain sea lion removal permits via an expedited process.

Related Pages:
Falling Prey by Eric Barker, Lewiston Tribune, 5/20/18
Hazing Sea Lions Not a Long-term Fix by Dameon Pesanti, The Dalles Chronicle, 5/11/18
Bill Would Streamline Process to Kill Sea Lions Near Bonneville Dam by Brian Brennan, KGW8, 4/4/18
'We're Losing' Sea Lion Fight by Dameon Pesanti, Spokesman-Review, 4/5/18
Sea Lions Focus of Fish Survival War by Gillian Flaccus, The Dalles Chronicle, 3/22/18

As Spring Chinook Arrive, Steller Sea Lion Presence at Bonneville Dam Breaks Single Day Record
Columbia Basin Bulletin, May 18, 2018

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