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If you haven’t delved into the details, the media headlines we see on Salish Sea orcas (also known as killer whales) can seem conflicting. On one hand, we hear about the whales being endangered, spending less time here and experiencing a population decline. On the other hand, we also hear about record sightings numbers and a booming population.
So which is it?
The answer is both! While they are still taxonomically considered members of the same species, Orcinus orca, two distinct populations, or ecotypes, frequent our local waters. Despite looking morphologically similar, nearly everything else about them is different, from their diet and travel patterns to their vocalizations and behavior. They live in the same waters but don’t interact or interbreed with one another at all: they’re really two different cultures of killer whale.
The first group area those you’re more likely to be familiar with. J-, K-, and L-Pods that make up the Southern Resident community used to be a near-daily presence around the San Juan Islands during the summer months. They’re considered the most closely studied population of cetaceans on the planet, and decades of research means we know them as individuals with traceable matrilineal histories. Iconic whales such as Ruffles and Granny were beloved for decades, and in more recent years, the stories of individuals like Tahlequah, who carried her deceased calf for 17 days in 2018, have captured media headlines around the world.
The Southern Resident population was hit hard by the live capture era of the 1960s and ’70s when orcas were removed from the wild for display in marine aquaria. Several dozen Southern Residents were either taken or killed during this time. While other orca populations have recovered or increased in the post-capture era, the Southern Residents have not. They are exclusively fish-eaters with a strong preference for chinook salmon, and a plethora of issues from over-fishing and dams to fish farms and climate change have impacted the prey sources they depend on.
They’ve shifted their historic travel patterns in response to their declining prey resources, and their search for food is further compounded by the toxic contaminants they carry in their blubber and the anthropogenic noise from vessel traffic that can mask their echolocation and communication. Their population currently hovers around 75 individuals and has continued to decline since their endangered listing in 2005.
For decades the “other” orcas of the Salish Sea were known as transients due to their habit of visiting less frequently and only staying a few days at a time, in contract to the “residents” who would often be here for weeks or months on end. The word “transient” is a bit of a misnomer, so they are now more commonly known as Bigg’s killer whales to honor the pioneering researcher Michael Bigg who was the first scientist to realize whales could be individually identified via their unique markings.
The Bigg’s killer whales are mammal-eaters, feasting locally on harbor seals, sea lions and porpoises. They used to be infrequent visitors; in fact, I spent four summers on San Juan Island in the early 2000s before I ever saw one. But as pinniped and porpoise populations recovered in the decades since the implementation of the Marine Mammal Protection Act, so too have the Bigg’s killer whales. The inner-coastal portion of the Bigg’s population currently totals over 380 individuals, about 250 of which visit the Salish Sea on an annual basis. The population has been growing at a rate of 2–4% per year in recent decades, and they’re now the whales that sometimes spend weeks on end in the Salish Sea taking advantage of the abundant prey resources available to them here.
At the Orca Behavior Institute, a small nonprofit research group based on San Juan Island, we track the Salish Sea habitat usage of both populations of killer whales to help document the changing trends. 2023 was a record year for Bigg’s killer whales with over 1,400 unique sightings (defined as a unique group seen on a unique day) over the course of the year. The Southern Residents, meanwhile, have found a “new normal,” where they are mostly absent in the months of April through August, visiting more in September through March, in part because they can take advantage of the fall and winter chum runs in Puget Sound that have fared better than the Fraser River chinook runs they typically relied on in the spring and summer.
The main difference is prey. The Bigg’s are showing us that it is possible to live in close proximity to an apex predator in the urban waters of the Salish Sea; it is up to us to see if we can make the changes needed to help support not just the Bigg’s but also the Southern Residents, who need healthy wild salmon populations in order to thrive.
— Contributed by Monika Wieland Shields
Shields will present on “A Tale of Two Killer Whale Populations: Comparing and Contrasting Southern Resident and Bigg’s Killer Whales in the Salish Sea” at the Jan. 24 Bellingham City Club meeting, beginning at Noon. Registration deadline is Jan. 21.
Also read in Salish Current:
- “Senate bill changing vessel-orca distance moves forward,” April 14, 2023
- “How much of orca decline is in their DNA?” Dec. 9, 2022
- “Author of ‘Orca’ has a message for the Northwest: hope has a price tag,” Sept. 14, 2021
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