Orcas & SALMON
Salmon abundance (specifically Chinook salmon) is the key to the survival of our Southern Resident killer whale (SRKW) population
This 15-second video ran on board Washington State Ferries during January 2018. The video was created to help elevate awareness about the importance of Chinook salmon in the survival of the Southern Resident killer whales (orcas).
Did you know?
At least 80% of the SRKWs' diet consists of Chinook salmon
Based on estimates of their food requirements, the average Southern Resident killer whale must consume 18-25 adult salmon daily just to meet its energy requirements.
The SRKW population must catch a minimum of 1,400 salmon daily to sustain their needs. Meaning 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.
About Salmon in the Pacific
Ref: Pacific Salmon Foundation
There are ten species of Pacific salmon. The seven that occur in the Pacific Northwest include Sockeye, Chinook, Coho, Pink, Chum, Steelhead Trout, and Cutthroat Trout.
Pink salmon are the smallest and most abundant species. Chinook salmon are the largest species (average size/30 lbs; very large/100 lbs) but least abundant species. Interestingly, Pink and Chinook have the same number of scales.
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.
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.
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 the development of extensive genetic diversity within each species, allowing the salmon to be highly adaptable.
Salmon often travel 30+ miles (~50 km) per day on their spawning journeys.
Female salmon lay 2,000 to 10,000 eggs; less than one percent of these eggs survive to produce the next generation of adults.
An adult Southern Resident orca eats 385 lbs.of fish/day
Chinook salmon - Southern Resident killer whale food of choice
In size, Chinook (Oncorhynchus tshawytscha)
are the biggest of the Pacific salmon species.
Chinook can weigh over 100 pounds, but on average hit the scales at about 30 pounds. They are long as well as heavy, ranging from 40 to 60 inches at maturity.
The heaviest Chinook on record was a 126-pound fish caught in a fish trap near Petersburg, Alaska in 1949. In the Pacific Northwest, Chinook varies significantly in size: 40-60 inches at maturity.
Spring, King, Tyee, Columbia River salmon, Hookbill, and Black or Blackmouth salmon.
Spotting a Chinook: Chinook salmon's nickname, Blackmouth, is derived from gumlines that look painted with black pigment. When not spawning, Chinook appears blue-green with silvery sides, and they have black spotting on their backs and dorsal fins and both lobes of their tail fin. When they are spawning, their color becomes richer: from deep red to coppery-black.
Habits and Habitat:
Chinook often prefers larger river systems for their freshwater stays but can also be found in small tributaries and headwaters. They are famous for their swimming endurance and the fantastic leaps they make when migrating. Chinook varies in their migratory habits with some displaying a strong urge to move oceanward within weeks of hatching, while others seem content to remain in freshwater for up to two winters.
Other Facts About Chinook:
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. They migrate to rivers for spawning throughout the year, but there is a seasonal peak from May to September. Adult Chinook (i.e., able to spawn) begin spawning as early as two years of age.
Chinook Runs in SRKW Critical Habitat
Along the United States west coast there are eight NOAA Fisheries designated Salmon and Steelhead recovery areas:
Puget Sound (which includes Hood Canal and Lake Ozette)
Interior Columbia (which has three sub-domains of the Middle Columbia, Snake, and Upper Columbia)
Willamette/Lower Columbia, Oregon Coast
Southern Oregon/Northern California Coast
North-Central California Coast, California Central Valley
South-Central/Southern California Coast
Puget Sound and 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 each with its own unique set of 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 populations of Puget Sound Chinook salmon have already become extinct.
Trends in coast-wide Chinook abundance have been estimated using data from the Paciﬁc Fishery Management Council and the Pacific Salmon Commission. The estimates are based on escape and terminal run size data, as well as harvest data for California, Oregon,
Research has shown that the death rate for SRKW correlates with coast‐wide Chinook salmon abundance (illustrated here). SRKW deaths have occurred in greatest numbers during dips and valleys in the coast-wide Chinook salmon abundance.
Chart courtesy of Jane Cogan, 2019.
Washington, and British Columbia (including SE Alaska harvests). According to the Pacific Salmon Commission, nearly all the Chinook salmon harvested in this region was destined to return to natal rivers in British Columbia, Washington, and Oregon.
What Can We Do?
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 1960‘s and 1970‘s 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?