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What animals prey upon salmon?

Pacific salmon are so important to the food web that scientists call them a "keystone species." Learn which animals need salmon to survive.

by | June 28, 2023

Grizzly bear eating a salmon
A brown bear enjoys a fresh-caught sockeye salmon. Trenton Schipper, CIAA

The recent post on this site, Have you ever wondered what salmon eat?, discusses what salmon find for forage throughout their growth and development. But what salmon are eating is only half of the picture. In fact, what eat salmon is arguably more important.

Pacific salmon holds a powerful place in the food web, which is a sort of visual representation of the circle of life. Because of this, Pacific salmon have earned the title of keystone species. A keystone species is one that other species in the food web depend on.

If salmon were to disappear in Alaska, it would be horrific not only culturally, but also for marine, freshwater, and land animals. Not only are salmon crucial to the Alaskan ecosystem, but they are also crucial to the Alaskan economy. 

Predators which feed on juvenile salmon

While juvenile salmon are growing up in freshwater lakes and streams, fish, birds, and small land animals feast upon them. Rainbow trout and Dolly Varden love to eat young salmon. Many commercial guide businesses would say that these fish wouldn’t exist without a fresh supply of salmon fry.

These two fish also eat salmon eggs, which is why you might fish for them using an artificial bead that looks like salmon roe.

We can also find birds cruising areas where juvenile salmon live. Gulls, kingfishers, terns and American dippers are all Alaskan birds that eat juvenile salmon. Small land mammals such as river otters, mink, and ermine will opportunistically feed on juvenile salmon as well. 

Juvenile salmon have adapted certain behaviors to try to avoid predation. Salmon lay eggs and cover their eggs with gravel to protect them. When they hatch and begin developing, alevin will stay in the gravel until they need to go searching for nutrients. When smolt migrate from fresh to saltwater they generally do so under the cover of night.

Animals that prey on adult salmon

Two orca swimming in Tutka Bay. Jasmin Estes, CIAA

As you might have guessed, the top predator of adult salmon is us. Through commercial and personal harvests, Alaskans use salmon as a major food source and source of income. Statewide commercial salmon harvest estimates total 160.7 million salmon including all five species in 2022.

Ocean predators include orcas, salmon sharks, and seals. In fact, those populations decline when there are fewer salmon. While marine populations are healthy in Alaska, where other salmon runs struggle, marine life that feeds upon them struggle too.

Consider the Southern Resident Orca population, often seen in Washington’s Puget Sound. This population uses Chinook salmon as its primary prey. Decreases in Chinook size and population have led to stricter protection to provide prey for Southern Resident Orcas.

When Pacific salmon enter freshwater on their way to spawn they encounter a new set of predators. Bears and wolves are both apex predators that use salmon as nutrients. Eagles will also clean up salmon scraps left by larger animals. If salmon make it all the way to successfully spawn their bodies will decay and provide nutrients to water and soil and the cycle will repeat itself once again.

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