SOUTHERN RESIDENT ORCAS & SALMON
Salmon abundance (specifically Chinook salmon) is the key to the survival of our Southern Resident orca population.
L84 catching a salmon.
Photograph by CWR’s ORCA SURVEY Lead Dave Ellifrit.
Did you know that at least 80% of the Southern Resident orcas’ diet is Chinook?
Southern Resident orcas & Chinook salmon
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Based on estimates of their food requirements, the average Southern Resident orca (SRKW) must consume 18-25 adult salmon daily to meet its energy requirements.
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The SRKW population must catch a minimum of 1,400 salmon daily to sustain their needs; this means that the Southern Resident community needs to capture at least half a million salmon a year. For the population to grow to 140 whales, an allowance of one million salmon a year is required.
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Salmon abundance determines year-round SRKW distribution and local habitat use.
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Fecundity—the ability to produce an abundance of offspring—is highly correlated with salmon availability. Currently, 69% of SRKW pregnancies end in miscarriage.
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Social groups are smaller and less connected in years of low Chinook salmon availability.
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Change in social networks caused by a lack of salmon may negatively affect the SRKWs’ long-term viability.
Orca with a salmon in 1979 (photograph by Ken Balcomb).
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Post-reproductive female orcas show greater guidance in leading their groups around foraging grounds in years of low prey levels.
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In years of low salmon returns, poisonous toxins accumulated in an orca’s blubber are released into the whale’s bloodstream.
CHINOOK (Oncorhynchus tshawytscha)
Southern Resident orcas’ food of choice
Nicknames:
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Spring, King, Tyee, Columbia River salmon, Hookbill, and Black or Blackmouth salmon.
Habits and Habitat:
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With long lifespans compared to other Pacific salmon, Chinook remains in the ocean for five or more years before returning to their natal spawning grounds
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They migrate to rivers for spawning throughout the year, but the seasonal peak is from May to September. Adult Chinook (i.e., able to spawn) begin spawning as early as two years of age.
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Chinook often prefers larger river systems for their freshwater stays but can also be found in small tributaries and headwaters.
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Chinook varies in their migratory habits, with some displaying a strong urge to move oceanward within weeks of hatching. In contrast, others seem content to remain in freshwater for up to two winters.
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Chinook is famous for their swimming endurance and the fantastic leaps they make when migrating.
Adult Southern Resident orca eats 385 lbs of fish each day.
Size:
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Chinook is the largest Pacific salmon species; they can weigh over 100 pounds but average about 30 pounds. They are long as well as heavy, ranging from 40 to 60 inches at maturity.
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The heaviest recorded Chinook was a 126-pound fish caught in a fish trap near Petersburg, Alaska, in 1949.
Spotting a Chinook:
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Chinook salmon’s nickname, Blackmouth, is derived from gumlines that look painted with black pigment.
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When they are spawning, a Chinook’s color becomes richer: from deep red to coppery-black.
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When NOT spawning, Chinook appears blue-green with silvery sides; they have black spotting on their backs and dorsal fins and both lobes of their tail fin.
About Salmon in the Pacific
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There are ten species of Pacific salmon. The seven that occur in the Pacific Northwest include Chinook, Sockeye, Coho, Pink, Chum, Steelhead Trout, and Cutthroat Trout.
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Pink salmon are the smallest and most abundant species. Chinook salmon are the largest species (average size/30 lbs; very large/100 lbs) but the least abundant species.
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Pacific salmon undertake anadromous migrations, meaning they reproduce in clean, freshwater streams, but rear for a portion of their life in oceans, where they accumulate more than 99 percent of their adult weight.
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Pacific salmon are also semelparous, meaning that most adults die after reproduction and become nutrients and food in the freshwater systems; they are the nutrient backbone of Pacific coastal ecosystems.
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Pacific salmon return “home” to their natal streams to reproduce; adults return to the same streams that their parents used (this behavior has resulted in extensive genetic diversity within each species, allowing the salmon to be highly adaptable).
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Salmon often travel 30+ miles (~50 km) per day on their spawning journeys.
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Female salmon lay 2,000 to 10,000 eggs; less than one percent of these eggs survive to produce the next generation of adults.
Source: Fisheries and Oceans Canada
Along the United States west coast, there are eight NOAA Fisheries designated Salmon and Steelhead recovery areas:
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Puget Sound (which includes Hood Canal and Lake Ozette)
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Interior Columbia (which has three sub-domains of the Middle Columbia, Snake, and Upper Columbia)
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Willamette/Lower Columbia, Oregon Coast
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Southern Oregon/Northern California Coast
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North-Central California Coast, California Central Valley
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South-Central/Southern California Coast
Puget Sound and the rest of the Salish Sea
In Washington State, salmon recovery is divided into Regional Fisheries Enhancement Groups. After Chinook was listed as endangered in 1999, the Puget Sound Recovery Plan identified 14 watersheds with unique priorities and recovery strategies.
In Puget Sound, only 22 of at least 37 historic Chinook populations remain. The remaining wild Chinook salmon are at 10% of their historic numbers. Of that 10%, most are concentrated in just two watersheds: the Skagit and Snohomish. The Chinook population is vulnerable to a catastrophic event. Nine Puget Sound Chinook salmon populations are already extinct.
Trends in coast-wide Chinook abundance are estimated using Pacific Fishery Management Council and Pacific Salmon Commission data. Escape and terminal run size data and harvest data for California, Oregon, Washington, British Columbia, and SE Alaska established the estimates. According to the Pacific Salmon Commission, almost all the Chinook salmon harvested in this region was returning to natal rivers in British Columbia, Washington, and Oregon.
Chinook Runs in Southern Resident Orca Critical Habitat
Coast-wide Chinook Salmon Abundance
Research has shown that the death rate for Southern Resident orcas (SRKW) correlates with coast‐wide Chinook salmon abundance (illustrated in this graph).
Southern Resident orca deaths have occurred in the most significant numbers during dips and valleys in the coast-wide Chinook salmon abundance.
Coast-wide Chinook Salmon Abundance
Click graph to enlarge
© 2021 Center for Whale Research.
Prepared by Jane Cogan.
Derivative use requires written approval.
Center for Whale Research ACTION
Examples of CWR actions to help restore Chinook salmon abundance for the Southern Resident orcas
ACTION: Center for Whale Research buys a 45-acre ranch along Washington State’s Elwha River.
In October 2020, CWR took a BIG leap into conservation to preserve salmon habitat by purchasing a ranch bordering both sides of the Elwha River, in a stretch of the mainstream river where most of the remnant native Chinook salmon now spawn. Our BIG LEGACY Project is named: BALCOMB BIG SALMON Ranch. The Chinook salmon abundance from the Elwha River ecosystem can provide a healthy food source for the SRKWs and a sustainable, nearshore artisanal fishery.
ACTION: Center for Whale Research ran video ads on board Washington State Ferries.
This 15-second video ran on board Washington State Ferries during January 2018. The video elevated awareness about the importance of Chinook salmon in the survival of the Southern Resident orcas.
ACTION: Center for Whale Research’s Ken Balcomb visits the Lower Snake River dams.
BALCOMB BIG SALMON Ranch along Washington State’s Elwha River.
Excerpt from an article Ken wrote following his visit to the Lower Snake River Dams in 2015.
I have studied the majestic Southern Resident killer whales of the Pacific Northwest for more than forty years (approximately one productive lifespan—whale or human), during which time much has been learned and shared with the world about this iconic endangered population. They are now arguably the best-known whales in the world! But, that was not always the case. The common response in the 1960s and 1970s to my announcement that I was studying whales was, “Why?” “What good are they?”My best response was to point out that as top marine predators whales are indicators of the health of that environment in which they live—the ocean—and that is also an environment upon which humans depend. Now, with growing numbers of people appreciating the whales’ natural role in the marine environment, and better understanding their ecological requirement for specific food—Chinook salmon in this case—to survive, the conversation has moved toward a strategy of how best to provide that food. There is currently an active discussion about removal of the Snake River dams to save fish, or whales. The issue of whether dams should be breached to provide this food for the whales has now arrived. Would that be reasonable? Are we sure that will work?
Lower Snake River Juvenile Salmon: Survival FACTS
