What Eats Salmon? A Look at the Many Predators of This Important Fish

Salmon are a crucial part of many ecosystems. As an anadromous fish salmon hatch in freshwater migrate to the ocean to grow and mature, and then return to their natal streams and lakes to spawn. During this epic journey, salmon interact with a wide variety of predators that depend on them as a key food source. In this article, we’ll take a closer look at the animals that eat salmon, from tiny insects to massive mammals.

Salmon Eggs and Alevins Have Plenty of Predators

The salmon lifecycle begins when adults lay their eggs in gravel nests or “redds” in freshwater streams and lakes. Once fertilized, the eggs incubate for several weeks or months before hatching into alevins. Both eggs and newly hatched alevins are vulnerable to predators, including:

• Other fish like trout, char, whitefish, and sculpins that eat salmon eggs and alevins.
• Aquatic insects such as caddisflies, stoneflies, mayflies, and dragonfly larvae prey on eggs.
• Crustaceans like crayfish and shrimp consume eggs.
• Amphibians including salamanders and turtles eat eggs and alevins.
• Birds like ducks, herons, and kingfishers feed on eggs and small fry.
• Semi-aquatic mammals such as otters, mink, and raccoons prey on eggs and young fish.

Salmon have evolved some defenses against this early predation, like burying eggs beneath gravel and nesting in areas with good water flow. But many eggs and alevins still get eaten before developing into fry.

Fry and Parr Face Predators in Freshwater

After absorbing their yolk sacs alevins emerge from the gravel as fry to actively feed and grow in their home streams and lakes. At this stage, juvenile salmon are called parr due to the parr marks or dark vertical bars that help camouflage them. Common parr predators include

• Larger fish like pike, bass, burbot, and bull trout that swallow small salmon.
• Aquatic mammals such as mink, otters, and seals chase down and eat parr.
• Wading birds like herons and egrets grab parr in shallow water.
• Kingfishers, mergansers, terns, and gulls are avian parr predators.
• Some terrestrial mammals like bears and raccoons catch parr when they venture near the shore.

To survive this onslaught of predators parr rely on their camouflage and by seeking shelter among vegetation roots, fallen logs, and cobbles in fast-flowing stream sections.

Estuaries Concentrate Predators Targeting Smolts

After spending from a few months to several years in freshwater, salmon transform into silvery smolts ready to migrate to the ocean. The journey from river to sea is perilous, as smolts must pass through estuaries where predators lie in wait. Key estuarine predators include:

• Large predatory fish like cod, pollock, tuna, sharks, and other marine fish ambush smolts in estuaries.
• Squids and octopuses lurk among dock pilings and grab passing smolts.
• Seals, sea lions, and even occasionally orcas hunt smolts in shallow estuarine waters.
• Wading birds like great blue herons stalk the edges of estuaries.
• Gulls, terns, cormorants, pelicans, and other seabirds fill the air above.
• Some land predators like foxes, coyotes, and raccoons patrol estuary shorelines.

To navigate this gauntlet, smolts travel on dark nights under cloud cover or during periods of high flow through estuaries on their seaward migration.

Hungry Ocean Predators Target Adult Salmon

Once in the open ocean, the number of potential predators expands exponentially for adult salmon. Here are some of the main oceanic predators of salmon:

• Larger fish and sharks including salmon sharks, mako sharks, and marine fish like cod, pollock, and halibut.
• Marine mammals like seals, sea lions, and orcas hunt adult salmon.
• Seabirds such as gulls, murres, puffins, and albatrosses may take salmon when they school at the surface.
• Squid and octopuses ambush unwary salmon in open water.
• Humans target salmon via commercial fisheries and sport fishing.

Adult salmon rely on their strong swimming abilities, schooling behavior, and cryptic camouflage patterns to avoid predators during their years roaming the ocean. Those that survive to adulthood have run a daunting predator gauntlet.

Spawning Salmon Contend with Terrestrial and Avian Predators

For salmon that complete their life cycle by returning to their natal freshwater streams and lakes, the journey isn’t over yet. Gathering at stream mouths and bottlenecks along their migration route, hungry predators await weakened spawning salmon. Key spawning salmon predators include:

• Bears eagerly await returning salmon, often at stream crossings and rapids.
• Canids like wolves, coyotes, and foxes patrol stream banks for sick fish.
• Raptors and eagles snatch adult salmon from shallow streambeds.
• Gulls compete with mammals and birds for weakened fish.
• Other opportunistic predators like mink, otter, turtles, and raccoons take advantage of abundant prey.

To survive the journey to their spawning grounds, salmon migrate in large numbers and during high flows to overwhelm gatherings of land predators. Their decaying bodies after spawning provide a pulse of marine nutrients into the freshwater ecosystem.

Humans Rely on Salmon as a Crucial Food Source

Finally, no overview of salmon predators is complete without mentioning the species that pursues salmon more intensely than any other – humans. As a nutritious source of protein and essential fatty acids, salmon have been a key food staple for indigenous peoples across the North Pacific for millennia.

Today, wild salmon still sustain human communities and cultures throughout their range. Commercial fisheries catch millions of adult salmon each year on their ocean migrations. Sport anglers prize chinook, coho, sockeye and other salmon species as top game fish. Subsistence and personal use fisheries provide families with salmon for nourishment.s rely on salmon more heavily than any other predator. As stewards of salmon ecosystems, we have an obligation to manage fisheries sustainably so that salmon can continue feeding ecosystems and people alike for generations to come.

The Salmon Lifecycle Runs a Predator Gauntlet

From tiny aquatic invertebrates feeding on eggs in stream gravel to massive brown bears snatching adult salmon from streams, salmon face predation pressures at every stage of their complex lifecycle. This predation shapes salmon populations and behaviors, while providing energy to a wide diversity of freshwater, estuarine, oceanic, and terrestrial food webs. By supporting abundant predators, salmon demonstrate their keystone role in ecosystems across the North Pacific.