On the Columbia River, a robust and growing population of California sea lions is preying on endangered and threatened stocks of salmon and steelhead that are listed for protection under the federal Endangered Species Act (ESA). Sea lion predation is occurring throughout in the lower river system, but the problem is especially acute below Bonneville Dam where returning salmon and steelhead congregate as they prepare to move up the dam’s fish ladders to spawn upstream.
Fish managers are also concerned about increasing predation by sea lions on mature sturgeon below Bonneville Dam and on listed salmon and steelhead runs in the Willamette River and other tributaries to the Columbia River. Human safety is also a concern. In recent years, there have been numerous reports of these powerful animals swamping boats and biting people along the Pacific coast.
Thirty-two wild salmon populations bound for the upper Columbia and Snake rivers are vulnerable to predation by sea lions immediately below Bonneville Dam. The population of greatest concern is the Upper Columbia Spring Chinook run, which is listed as endangered under the Endangered Species Act (ESA). Snake River Spring/Summer Chinook, listed as threatened under the ESA, are also highly vulnerable to predation by sea lions feeding in spring immediately downriver from Bonneville Dam. Other ESA-listed salmon and steelhead populations passing through the lower Columbia River when sea lions are feeding include Lower Columbia River Chinook, Lower Columbia River steelhead, Middle Columbia River steelhead, Snake River Basin steelhead, Upper Willamette River Chinook and Upper Willamette River steelhead. All are listed as threatened under the ESA.
Since 2002, the Army Corps of Engineers has recorded the number of salmon and steelhead consumed by California sea lions annually from January through May immediately below Bonneville Dam. In 2005, for example, the Corps watched sea lions consume 3,023 fish in a year when ESA-listed upriver chinook stocks made up 14.5 percent of the run.
Besides recording the number of fish taken, the U.S. Army Corps of Engineers also documented a sharply increasing number of sea lions foraging at the dam. That number has grown from six sea lions in 2001, to 31 in 2003, to approximately 100 sea lions annually since 2004. Until the mid-1970s, California sea lions were seldom seen anywhere on the Columbia River.
The Corps’ data only includes observations of fish taken by sea lions above water immediately below Bonneville Dam. A biometric model, based on California sea lions’ metabolic needs, indicates that 100 animals feeding in that area may consume as many as 13,000 salmon each spring. In addition, sea lions are foraging in the other 140 miles of the lower river, and in tributaries.
California sea lions are found all along the west coast of the North America from Mexico to southeast Alaska including the mouth of the Columbia River. However, in recent years their numbers and distribution have increased significantly in the Columbia River system all the way upriver to Bonneville Dam. Until the early 1980s, it was uncommon to see a California sea lion in the Columbia River. Since then, migrant animals from California and Mexico have appeared in the river seasonally from January to late May in dramatically increasing numbers – first in the river estuary, then in the tributaries and finally upriver to Bonneville Dam, 145 miles from the river mouth. A 2006 survey conducted by the Washington Department of Fish and Wildlife (WDFW) estimated up to 1,200 California sea lions and 1,000 Steller sea lions in the lower Columbia River.
California sea lions are a distinct species from Steller sea lions. The Steller sea lions’ diet relies more on marine fish than on salmon and steelhead. Steller sea lions are not a target of lethal removal efforts.
In the spring of 2005, 2006 and 2007the Washington Department of Fish and Wildlife (WDFW), the Oregon Department of Fish and Wildlife (ODFW) and other partners made a concentrated effort to drive California sea lions away from the area below Bonneville Dam. Partners in this effort included the Columbia River Inter-Tribal Fisheries Commission, National Marine Fisheries Service (NMFS) and the U.S. Army Corps of Engineers. Despite hazing tactics that included underwater firecrackers, acoustic devices and boat hazing, the sea lions returned to the area within a short period.
Sea lions naturally haul out of the water and rest on structures such as jetties and docks. They will also haul out into floating cages, which are used by wildlife biologists to capture these animals. In a typical operation, a biologist leaves the door to the trap open until one or more animals are inside, then trips the door shut.
Precautions are taken to ensure that no animals are inadvertently shut inside the cage traps. Doors to the traps are locked open to prevent them from closing accidently when the traps are unattended. The Corps has updated its surveillance systems at Bonneville Dam and monitors the entire area where the traps are set up.
There are some positive signs, but it is too soon to assess the success of the states' efforts. The good news is that the number of California sea lions feeding in the tailrace area has declined from a high of 104 animals in 2003 to 39 in 2012. The percentage of protected salmon and steelhead runs consumed by California sea lions has also declined in recent years, although that trend is partly due to larger salmon runs in recent years. Run timing and river conditions also affect predation rates, complicating an assessment of the states' efforts.
No. California sea lion numbers have grown rapidly since the 1970s and the species is now at "carrying capacity" - near the highest level the environment can sustain - according to wildlife biologists. The U.S. population of California sea lions is estimated at some 300,000 animals, all on the Pacific coast. By comparison, the overall Pacific coast population of California sea lions was 10,000 in the 1950s. An aerial survey conducted in 2011 by the Washington Department of Fish and Wildlife documented over 2,000 California sea lions on the South Jetty at the mouth of the Columbia River alone.
Previous efforts to relocate sea lions have been largely unsuccessful because sea lions frequently return to the site of capture. The experience with sea lions at the Ballard Locks in Seattle in the late 1980s is a prime example. In 1988 and 1989, resource managers captured a total of 39 California sea lions that had been foraging at the Ballard Locks and transported them to the outer Washington coast near Long Beach where they were released. Within a few weeks of the time they were released, 29 of those animals returned to the Locks to resume preying on salmon and steelhead in Shilshole Bay. The result was much the same the following year, when resource managers transported six California sea lions back to their breeding area off the coast of southern California. Three of those animals returned to Puget Sound within 45 days and a fourth was sighted in the Columbia River.
Three California sea lions that had been foraging near the Locks were captured and transferred to SeaWorld in Orlando, Fla., in 1996. Resource managers have initiated contact with accredited zoological facilities about the possibility of taking additional animals, but it is unlikely that demand will be sufficient to ease predation on protected salmon and steelhead populations on the Columbia River. A final determination on whether any California sea lions could be moved to captivity would be made by NMFS, based on the federal agency's assessment of the adequacy of captive facilities as well as the risk of possibly exposing healthy captive animals to diseases carried by wild animals.
Left unchecked, California sea lions could undermine the recovery of threatened and endangered salmon and steelhead runs moving through the lower Columbia River. For some stocks, recovery efforts involving reduced fishing opportunities have been under way for decades. Since the 1990s, recovery efforts have expanded to include mitigation efforts and billions of dollars in public investment.
Previous experience with California sea lions at Seattle’s Ballard Locks demonstrates the risk these animals can pose to vulnerable fish stocks. From the early 1980s through the mid-1990s, resource managers tried a variety of methods to deter sea lions from preying on Lake Washington winter steelhead. Those efforts were unsuccessful, and sea lion predation continued until the run was effectively destroyed. Today, Lake Washington winter steelhead remain at critically low levels and the population is not expected to recover. With sea lion numbers and predation increasing on the lower Columbia River, fish managers fear some Columbia and Snake River stocks could meet the same fate.
Yes. There has been an extraordinary and growing effort in this region to protect and recover salmon and steelhead populations. Recovery plans are being developed in every watershed to restore important habitat, improve dam passage survival, reform hatchery programs to assist wild fish populations, and reshape fisheries by focusing on selectively harvesting healthy, hatchery fish. The people of the Northwest have supported restoration efforts, and borne the costs, because of the importance of salmon to our heritage, the cultural value to Native Americans, and the economic value of salmon to our fishing communities.
Active intervention and additional wildlife-management methods are required to restore balance between the growing number of California sea lions and endangered and threatened stocks of salmon and steelhead. The states of Washington and Oregon expanded hazing efforts in the spring of 2007, shifting to daily deterrence efforts as compared to the previous year’s four days on, four days off hazing schedule. In addition, Washington, Oregon and Idaho have petitioned the federal government for authority to use lethal means if necessary to remove individual sea lions from the vicinity of the dam, and to remove marked sea lions that have preyed on salmon near the dam. The states applied for this removal authority under Section 120 of the Marine Mammal Protection Act.
The states have been trapping and branding California sea lions in Astoria since 1997 as part of long-term study to monitor the movement, feeding habits and migration patterns of the animal in the Columbia River and along the Pacific Coast. By re-sighting individual animals throughout their lives, we can learn about age-specific survival, habitat use, age at sexual maturity, reproductive rates and longevity. All of this information is crucial to understanding sea lion life history in order to insure the overall health and well-being of the population.
Branding is the only permanent way to mark a California sea lion. Wildlife managers have been hot branding seals and sea lions for over 50 years. The process is not inhumane. All of our capture and marking procedures have been reviewed and approved by our Institutional Animal Care and Use Committee, which includes experience veterinarians, species experts, and unaffiliated members of the general public, as dictated by the federal Animals Welfare Act.
The hot brand is applied for 2-3 seconds to burn the hair and the very top layer of skin so the hair can’t grow back. While the process and the brand itself may look painful and raw to us, the skin of a California sea lion is very different that than of a human. It’s thicker and tougher, and has few nerve endings.
Since 1997 we have branded nearly 1,400 California sea lions in Astoria. In that time, we have never had an animal die due to branding. In fact, most sea lions react very little to the branding event.
The authority granted under Section 120 of the Marine Mammal Protection Act, state resource managers are allowed to remove a limited number of California sea lions that have been identified as preying on salmon and steelhead in the area below Bonneville Dam. For more information.
Washington and Oregon fish and wildlife departments have each received annual grants of $100,000 to $150,000 from the Pacific States Marine Fisheries Commission to support their work with pinnipeds, including state wide food habits studies, capture and marking at Astoria, capture and marking at Bonneville, boat survey of pinnipeds in the Columbia River, field work for all the different tasks, equipment, supplies, maintenance, office time for data analysis and presentations.
In past years, each state has also contributed approximately $15,000 for early-season hazing efforts designed to protect sturgeon, but the Columbia River Inter-Tribal Fish Commission has assumed this responsibility.
The Army Corps of Engineers provides approximately $150,000 per year to document predation, haze sea lions and conduct fieldwork related to sea lion predation. This is in addition to the Corps' $3 million investment to install heavy bars and sonic devices to keep sea lions out of fishways and ladders at Bonneville Dam.
Under the Marine Mammal Protection Act, regulatory authority over sea lions rests exclusively with the federal agency, NOAA Fisheries. NOAA Fisheries’ Northwest Regional Office has posted a website that answers many of the questions anglers may have about protecting themselves from aggressive sea lions while fishing. ODFW encourages anglers to visit NOAA Fisheries’ Deterring Problem Seals & Sea Lion page.