What Do Salmon Eat? Everything You Need to Know

Quick Take

Salmon are capable of living in freshwater and saltwater.
A salmon’s diet depends on its life stage and environment.
Humans are the number one predator of salmon.

Most salmon (Salmonidae) are anadromous, meaning that they can live in freshwater and saltwater. Salmon hatch in freshwater rivers and streams, where they spend their juvenile years feeding and growing. They then migrate to the ocean, where they spend up to six years foraging and maturing. Once mature, they return to freshwater to spawn. There are, however, some landlocked populations that spend their lives entirely in freshwater. Salmon are generally considered opportunistic feeders that consume a diverse diet, which is dependent on their stage of life. Continue reading to discover everything you need to know about what salmon eat.

Kokanee Creek Salmon Run — Though they are typically silver, some species of salmon turn bright red when they are spawning.
©StephenBridger/iStock via Getty Images

What Foods Do Salmon Eat?

The diet of a salmon varies, changing with its age, size, and location as it migrates between freshwater and saltwater. Salmon are carnivorous, but their prey ranges from microscopic plankton when they are young to larger fish as they mature.

Salmon are opportunistic hunters that consume whatever prey is most abundant and available in their immediate environment, including:

Zooplankton
Shrimp
Mayflies
Stoneflies
Sand eels
Grasshoppers
Sprats
Herring
Crayfish
Caddisfly larvae
Krill
Squid.

Juvenile salmon eat insects such as mayflies and caddisfly larvae. As adults, they become larger and more capable hunters in saltwater, where they feed on other fish, crustaceans, and squid.

Salmon have an incredible sense of smell that helps them track potential prey and helps guide them back to the original stream from which they spawned at the end of their lifecycle.

Landlocked salmon are also carnivorous, feeding primarily on small fish and aquatic insects throughout their lives in freshwater lakes. Their diet shifts with age, starting with insect larvae as juveniles, becoming dependent on small forage fish as adults.

What Do Salmon Eat in Captivity?

Salmon are among the most commonly farmed and caught fish in the world. The process of raising and harvesting salmon is called aquaculture.

Salmon farms consist of hatcheries and sea cages made of mesh, which can measure over 100 feet across and 30 feet deep.

Largest salmon - spawning sockeye salmon — While in freshwater, salmon mostly eat insects like mayflies and fly larvae.
©907Shots/Shutterstock.com

Farm-raised salmon eat specially formulated pellets. Salmon pellets contain a variety of ingredients, including:

Plant and vegetable material
Grains
Fishmeal
Vitamins
Minerals
Amino acids.

These pellets are fed to salmon at regular intervals to bolster their growth and prepare them for harvest. The fish are harvested when they are 12 to 24 months old and weigh between eight and 12 pounds. Although they can grow much larger, this size is considered the ideal market weight.

How Much Do Spawning Salmon Eat?

Once salmon return to their spawning grounds, they stop eating. This means they need a significant amount of stored energy before their journey, known as the salmon run.

During the salmon run, the fish make their way back to where they started life. Having put all of their energy into reproduction, Pacific salmon die once they have spawned. Unlike Pacific salmon, Atlantic salmon do not necessarily die after spawning. While the vast majority die from exhaustion, some Atlantic salmon, called kelts, survive to spawn multiple times.

What Predators Hunt Salmon?

Salmon often fall prey to other creatures. Their agile swimming and keen vision can sometimes help them avoid danger, but not always. Chief among their predators are humans, who catch salmon in freshwater and saltwater and farm them for food. In this way, millions of salmon are killed every year.