Vital Signs | Orcas

PUGET SOUND VITAL SIGNS

Measures of ecosystem health and progress toward Puget Sound recovery goals

Orcas

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Orcas, or killer whales, are among Puget Sound’s most distinctive and charismatic creatures. They are icons in Pacific Northwest culture and top predators of the marine ecosystem. Southern Resident killer whales are a distinct population listed as “Endangered” under the federal Endangered Species Act. They range in three pods known as J, K and L from California to Alaska in pursuit of fish, primarily adult Pacific salmon. Bigg’s or transient killer whales also frequent Puget Sound, but they eat marine mammals like seals, sea lions, and porpoises. This Vital Sign tells us about the condition of both the Southern Resident Killer Whales and the Bigg’s or transient killer whale populations.

VITAL SIGN INDICATOR	PROGRESS	STATUS

VITAL SIGN INDICATOR	PROGRESS	STATUS

Key Vital Sign Messages

Southern Resident killer whale catching a salmon, NOAA Northwest Fisheries Science Center.

Southern Resident killer whales once numbered around 200 whales but were down to 72 wild individuals during the 2020 census.

Over the past several years the Southern resident killer whale population has continued to decline, although three calves were recently born. In contrast, the transient killer whale population continues to steadily increase at what is likely a near maximum rate.

Year-round, Southern Resident killer whales depend heavily on Chinook salmon for food, thus linking orca recovery with the Chinook salmon, a threatened species whose numbers reported in the Puget Sound Vital Signs are dangerously low and showing few signs of recovery.

Southern Resident killer whales spend a considerable portion of the year outside the Salish Sea, where they eat Chinook salmon from Puget Sound and other regions of Washington and Oregon — including the Columbia Basin — as well other areas, like the Fraser River in British Columbia and the Klamath River in California. Therefore, improving prey availability outside Puget Sound is also fundamental to resident orca recovery.
Southern Resident killer whale's use of the Salish Sea, particularly in summer, has steadily declined over the past several years. Conversely, Bigg’s killer whale’s use of the Salish Sea has dramatically increased.
When Southern Resident killer whales can’t find enough to eat, they must burn their own fat, thereby increasing circulation of harmful pollutants picked up from the Salish Sea and elsewhere. Science suggests that poorer body condition increases the orcas’ vulnerability to disease and hinders reproduction. The Toxics in Fish Vital Sign raises concern over the presence of human-made contaminants throughout the food web.
In the Salish Sea, underwater noise and disturbance from commercial and recreational vessels cause Southern Resident killer whales to forage less efficiently for salmon that are now more scarce and smaller than in decades past. Boats at ranges less than 400 yards are associated with fewer and shorter foraging dives and more shifts by females to non-foraging behavior. Reducing vessel noise that masks echolocation and communication to improve access to prey and increasing salmon supply are both crucial for orca recovery.
Because disease can cause increased morbidity and mortality in orcas, reducing pathogens in their environment through improved marine water quality should complement reduction of the key threats to Southern Resident recovery: contaminants, decreased prey, and vessel disturbance.