About wild salmon: The basics
Wild salmon are amazing creatures in many ways.
Read on to learn more about their culinary and nutritional attributes, the crucial role they play in the Pacific Northwest ecology and culture, and the threats posed by salmon farms.
Which species should I choose?
Ultimately, it's a matter of taste — these culinary and nutritional distinctions may assist your choice.
King (pictured at right) is the fattiest Pacific species, while sockeye features the strongest flavor and firmest texture, and cooks more quickly than the other species — usually in just 6 to 7 minutes.
Silver is generally milder and softer than sockeye and king, while keta and pink are generally the mildest and softest salmon.
Nutrition numbers for wild salmon vary by harvest season, year, and location.
The USDA reports these average quantities per 100 gram (3.5 oz) serving:
|Species||Total fat (grams)||Total Omega-3s (mg)|
NOTE: While farmed salmon has comparable omega-3 levels, its unnatural diet gives it high, pro-inflammatory levels of omega-6 fats. See “Farmed Salmon's Diet Yields Unhealthful Cardiovascular Effects” and our Omega-3/6 Balance page.
Wild salmon is also the richest food source of astaxanthin (as-tuh-zan-thin) … a carotene-class red-orange pigment with strong antioxidant, anti-inflammatory properties.
Sockeye salmon has the highest astaxanthin levels, which explains the species' deep red-orange color and its other common name: “red” salmon.
Wild Pacific salmon species
For thousands of years, salmon have defined the culture, ecology, and nutrition of Pacific Northwest plants, animals, and native peoples.
Wild Pacific salmon boast very high levels of omega-3 fatty acids and vitamin D3, and relatively little omega-6 or saturated fats — attributes that make them an exceptionally healthful and sustainable high-protein food.
Unlike most trout species, salmon and other "anadromous" fish — such as shad and steelhead trout — migrate from their freshwater birthplace to the ocean, where they live for two to six years (depending on the species) before returning to their birth stream or river to spawn (reproduce).
The fat content of salmon is linked to the length of their fresh-water migration, because salmon stop feeding after they start upstream.
Some salmon — like Yukon and Copper River king — swim hundreds of miles upriver to spawn, and put on lots of fat, including omega-3s, for their epic journey.
Once at the spawning ground, female salmon create a shallow nest, and signal male salmon to come fight for the right to spread their sperm over her eggs as she's giving birth.
The fertilized eggs hatch in three to four months, and the baby salmon or "fry" are born with a some attached yolk as short-term food. They then eat most anything around, grow to about one inch long, and begin swimming downstream to the sea to start the cycle all over again.
Wild salmon in the ocean are mostly silver, with some blue-black highlights, as shown at right.
But when they begin their journey upriver to spawn, they undergo striking changes in color and shape designed to attract mates, as shown at left.
All six Pacific species belong to the genus Oncorhynchus, while the sole Atlantic salmon species belongs to the genus Salmo.
Both salmon genera belong to the family Salmonidae, which includes trout.
These are the six Pacific Ocean species:
- Sockeye/Red (O. nerka)
- Silver/Coho (O. kisutch)
- Chum/Dog/Keta (O. keta)
- Cherry/Seema (O. masou)
- King/Chinook (O. tshawytscha)
- Pink/Humpback (O. gorbuscha)
Sockeye, pink, and keta salmon are found on both sides of the North Pacific Ocean.
King and silver salmon occur only off British Columbia (Canada), Alaska, and the U.S. Pacific Northwest.
Cherry salmon occur only off Japan, Korea, and eastern Russia.
What do salmon eat?
Salmon diets vary by species and region, but young salmon mostly eat zooplankton (including tiny, shrimp-like krill) and invertebrates.
In the ocean, salmon eat smaller fish such as herring, plus krill and pelagic amphipods (close oceanic cousins to sand hoppers).
Which animals eat salmon?
The list of animals that prey on salmon varies over the course of a salmon's life.
Baby salmon fall prey to bigger fish (including older salmon), snakes, and birds. Once out in in the ocean, salmon fall prey to whales, dolphins, seals, sea lions, bigger fish, and humans.
Bears and birds feast seasonally on salmon that've returned to their birth rivers to spawn, and those predators often end a salmon's life.
Salmon in the trees
It's hard to overstate the importance of these keystone species to trees and wildlife, including birds, bears, and wolves ... and to coastal peoples for whom the fish are a vital food and cultural touchstone.
The region’s grizzly bears, who gorge on salmon ahead of their long winter nap, often top 1,000 lbs. And, fed by the nutrients from wild salmon, regional Sitka spruce soar 150 to 225 feet into the sky.
Critically, waste matter from the thousands of creatures that feed on dying salmon in any given river sows nitrogen and other nutrients well into the surrounding forest, fertilizing countless plants and trees. Some scientists call wild salmon the ultimate "biological power cable" — one that brings energy and nutrients from blue surf to green turf.
Scientists verified the value of salmon to Northwest coastal rainforests after finding nitrogen 15 — an isotope that's unique to the ocean — in trees near salmon streams.
Thanks to this bio-marker and others, scientists can gauge the health of a salmon run by examining the surrounding forest over time — even a casual look can reveal a lot.
How mining, logging, and salmon farms can hurt
Salmon return to the exact spot where they hatched, and this homing behavior depends on olfactory (smells) memory.
Even small changes in the mineral or metal content of streams can keep salmon from finding their way home, which is why — in addition to banning salmon farms — Alaska's state constitution prohibits contamination of salmon rivers by mining and logging operations.
Research published since the 1970s documents the harm caused to wild salmon by salmon farms, which spread disease and sea lice to wild salmon migrating past the aquaculture pens.
Alaskan law prohibits salmon farming in state waters.
Atlantic salmon are industrially farm-raised in many parts of the world, including Norway, Ireland, Scotland, Chile, and British Columbia in Canada.
To a much lesser extent, Pacific king (chinook) and silver (coho) salmon are farm-raised, in New Zealand, Chile, and Washington State, with some silver salmon being raised indoors.
To learn more, browse the articles in the Farmed Salmon section of our newsletter archive.