All wild Pacific salmon are rich in omega-3s, antioxidants, and vitamin D—factors that make them all exceptionally healthful.
But there are significant differences among them in terms of total fat content and omega-3 content… and their varying fat levels also affect these fishes' calorie counts.
One customer's fatty question
Why does king salmon have the most omega-3s of all types of salmon
Does it depend on where it lives and what it eats compared with the other kinds?
Generally speaking, salmon that have more total fat will also have more omega-3 fatty acids, which constitute part of any fish's fat content
Diet plays a role in the differing average fat contents of the several Pacific salmon species, but, rather than diet, variations in the body size and fat content of wild salmon species have more to do with the length of their birth river and their natural habitats.
Salmon that spend more time in colder waters and undertake longer migrations up their birth rivers to spawn will accumulate more fat, including omega-3s.
This table shows the fat and omega-3 content of the wild salmon species we offer, per 3.5 oz (100 g) serving. These are averages, because the nutrient content of individual salmon will vary within each species, depending on the year and their harvest location:
|Total Fat (grams)
|| Omega-3s (grams)
Note: The omega-3 figures shown for each product — which come either from USDA data or our own test results — may vary somewhat from the averages used in our Seafood Nutrition Chart.
The omega-3 distinction
Omega-3 fatty acids can be thought of as the “anti-freeze” of the fat world, because these polyunsaturated fats remain fluid in fish that swim frigid ocean waters
This explains why omega-3s levels are usually highest in salmon that come from and return to the coldest rivers, and swim in the coldest ocean waters.
King salmon have the highest omega-3 levels of all Pacific salmon species in part because they favor deeper, colder waters during the ocean phase of their lives.
The total-fat distinction
While it may relate in part to water temperature, the distinctive total-fat content of each wild salmon species has a different explanation.
Pacific salmon stop feeding once they leave the ocean and begin to swim up their birth rivers against the current, so they must return from the ocean with sufficient energy (fat) reserves to sustain them during this strenuous final phase of their life cycle.
King salmon have evolved to favor larger rivers that require longer migrations, so they have the greatest need for stored energy.
Sockeye also tend to migrate further distances during the foodless, fresh-water part of their lives, so they often rank second to King salmon in terms of total fat content.
In contrast, pink and keta (chum) salmon spawn in estuaries, or small channels near them (respectively), so have the shortest migration and correspondingly lowest fat levels.
Silver (coho) salmon, which spawn in tributaries rather than lengthy rivers, occupy the midrange on the fat scale. (Interestingly, silver salmon are known for their jumping ability, which helps them surmount logjams and other obstructions common in small streams.)
Fat levels within individual species may vary dramatically depending upon the temperature, length, and steepness of their birth river.
For example, the fattiest, richest king salmon come from the Yukon River, which is both the coldest and longest of Alaska's salmon-spawning rivers.
And because the Copper River is a relatively “steep”, swiftly flowing river, so sockeye and king salmon swimming against this current must accumulate greater energy (fat) reserves than salmon returning to other rivers.
In contrast, Bristol Bay sockeye and king salmon, which have a relatively easy migratory journey, may have only half as much fat as their Copper River counterparts.
The vitamin D distinction
You didn't ask, but it's important to know that Pacific wild salmon (and albacore tuna) have much higher levels of vitamin D than other common foods, including farmed Atlantic salmon
But, at about 687 IU per 3.5 oz (100 gram) serving, sockeye salmon has more vitamin D than any other salmon.
It's not clear why this is, because the normal sockeye diet — zooplankton (such as krill), small adult fishes, and (occasionally) squid — resembles that of all other Pacific salmon species except king salmon, which feed almost exclusively on fish.