A pod of southern resident orcas.
Courtesy of National Oceanic and Atmospheric Administration Fisheries
The number of southern resident orcas that forage along the Oregon Coast has been on the decline for decades as they struggle to find food and confront boats and pollution.
Just 73 are left, down from a peak of nearly 100 in the late 1990s. Officials from the National Oceanic and Atmospheric Administration’s fisheries division project the number could decline by half during the next 20 years.
Now, the state’s Fish and Wildlife Commission will weigh whether to add the orcas to the state’s endangered species list, creating more protections for the orcas and directing more conservation money toward their survival. The Oregon Department of Fish and Wildlife on Thursday produced an assessment of the situation that the commission will review. Southern resident orcas are already listed as endangered under the federal Endangered Species Act and in Washington and Canada, where they also live and forage. Being listed under Oregon’s Endangered Species Act would offer even greater protections, according to Miyoko Sakashita, oceans program director for the nonprofit Center for Biological Diversity.
“While the federal listing is helpful, some of its provisions only apply to federal actions,” Sakashita said via email. “By having a state listing, the state has more powerful tools to address threats to orcas and their salmon prey.”
If listed, the Oregon Fish and Wildlife Department would need to develop a management plan and coordinate with other state agencies to take action and address the primary threats to orcas in Oregon. The commission is scheduled to decide whether to add the southern resident orca to the state’s endangered species list by February 2024.
The primary threats to southern resident orca survival include a lack of salmon to eat, pollution from chemicals and oil spills and disturbances from boats, including sounds from the boats.
“It is unclear, and may be impossible to determine, which threat or threats pose the highest risk for the survival and future existence of the southern resident orcas,” the biological assessment from Oregon’s fish and wildlife agency states. “It is highly likely that the southern residents experience cumulative, and probably synergistic, effects from multiple threats, and that these effects are exacerbated by the population’s small size.”
The orcas rely mostly on Pacific salmon for their diet, including a great deal of Chinook salmon originating in the Columbia River and in Oregon tributaries and hatcheries. Declines in those fish populations and their physical size are impacting the orcas, who are getting less calories from the fish, the researchers found.
Chemicals, including some previously used in coolants, such as PCBs, and insecticides such as DDT have been found stored in salmon the orcas eat and in the orcas’ blubber. These chemicals have been found to cause cancers, endocrine and immune system disruptions, decreased reproduction and calf mortality.
Modeling suggests it could take up to 60 years for concentrations of PCBs in the bodies of southern resident orcas to fall below levels considered harmful to marine mammals.
A challenging history
Southern resident orcas are one of three sub-species of killer whales in the Northwest Pacific, and their range spans southeastern Alaska to central California.
Transient killer whales are by far the most frequent sub-species of killer whales to frequent Oregon’s inner-coastal waters, feeding on other mammals such as harbor seals, harbor porpoises and Steller sea lions. They are believed to number more than 400 and are increasing every year. Occasionally seen in Oregon waters are so-called offshore killer whales, which feed primarily on sharks and other fish. They have also been known to hunt gray whale calves in Monterey Bay and can be found in the open ocean stretching from the eastern Aleutian Islands of Alaska to southern California.
For the southern orcas, the Oregon Coast is important habitat for them as they navigate the waters between Cape Meares and the California border, moving foraging areas.
The population first took a hit in the 1960s and ‘70s, when they were captured and brought to large aquariums globally. Population sizes have varied since then, with a peak of 98 southern resident orcas in 1995. Since then, numbers have declined. When southern residents were federally listed in 2005, there were just 88 left.
Such a small population can lead to inbreeding and other reproductive issues, which have become more prevalent, according to the biological assessment.
Scientists have found orca females suffering late-term miscarriages and a growing number of females of reproductive age that have not given birth.
Scientists discovered that two male orcas sired half of the southern resident calves born between 1990 and 2015 and found at least four of the offspring were “highly inbred.”
The effort to get southern resident orcas listed in Oregon was spurred by a petition filed in February by the Center for Biological Diversity, Defenders of Wildlife and Whale and Dolphin Conservation.
“I’m heartbroken to learn that southern resident orcas are struggling as much as we feared,” Sakashita said in a statement. “But the good news is that Oregon’s report gives us support for protecting orcas under the state’s Endangered Species Act. More help from the state can’t come soon enough, especially given how important Oregon’s coastal waters are for orcas.”
This story was originally published by the Oregon Capital Chronicle. Oregon Capital Chronicle is part of States Newsroom, a network of news bureaus supported by grants and a coalition of donors as a 501c(3) public charity. Oregon Capital Chronicle maintains editorial independence. Contact Editor Lynne Terry for questions: info@oregoncapitalchronicle.com. Follow Oregon Capital Chronicle on Facebook and Twitter.
