What Do Salmon Eat? A Detailed Look at the Salmon Diet

Salmon are amazing fish that are popular for both commercial fishing and recreational sport fishing. But have you ever wondered – what do salmon eat?

As carnivorous fish, salmon have a varied diet that changes as they move between freshwater and saltwater habitats during their complex lifecycle. I did deep research into the salmon diet and feeding habits so you don’t have to!

Here’s a comprehensive look at what salmon eat at each stage of their lives

Salmon Fry and Juveniles – Insects, Zooplankton, and Small Crustaceans

After hatching in freshwater streams and rivers, young salmon are called fry. At this stage, they feed on tiny aquatic insects and insect larvae, like mayflies, stoneflies, caddisflies, and midges.

As the fry grow into juveniles or “parr,” they start eating larger foods like zooplankton, amphipods, and other small crustaceans. Parr have camouflaging vertical stripes that help them hide from predators as they feed in shallow water.

Some favorite foods for parr include:

• Scuds
• Amphipods
• Aquatic insect larvae
• Terrestrial insects that fall into the water
• Copepods
• Cladocerans
• Ostracods

Smolts – Transitioning to the Ocean Diet

When juvenile salmon reach a certain size, they go through a physiological change called smoltification to prepare for saltwater. At this “smolt” stage, the diet starts shifting towards foods found in the ocean.

Before migrating downstream, smolts may still eat aquatic and terrestrial insects. But they also start targeting larval fish, small shrimp, marine worms, and other ocean-based prey.

Adult Ocean Phase – Fish, Squid, Plankton, and More

As adult salmon journey out to sea, they become powerful ocean predators. The diverse open ocean diet includes:

• Small fish like herring, sand lance, and capelin
• Large zooplankton like krill
• Squid
• Shrimp
• Crab larvae
• Amphipods
• Copepods
• Fish eggs

Sockeye salmon tend to eat more zooplankton like krill. But kings, chum, and silvers feast on higher-protein fish like herring.

Some salmon even eat other smaller salmon! Overall, their ocean diet provides the energy reserves needed for the strenuous spawning migration.

Spawning Salmon – No Food at All!

Here’s a surprising fact about the salmon diet – when adults return to freshwater to spawn, they stop eating completely!

Spawning salmon do not feed at all for weeks or months. They rely fully on the fat stores built up in the ocean to fuel their upriver migration, maturation, and nest building.

By the end of the exhausting journey, salmon are emaciated and near death. They use their last reserves of energy to spawn, and then die soon after laying and fertilizing the eggs.

The salmon carcasses provide a nutrient boost to the stream ecosystems, supporting the next generation.

Key Takeaways on the Salmon Diet and Feeding

To sum up this deep dive into what salmon eat:

• Young salmon start with insects and zooplankton in freshwater
• The diet shifts to fish and squid in the ocean
• Spawning salmon don’t eat at all and rely on fat reserves
• Habitat and life stage determine the salmon diet

Understanding what salmon eat helps fisheries managers and conservation groups make informed decisions. For example, hatcheries like Cook Inlet Aquaculture Association can use the right feed to raise healthy juveniles.

Wild salmon primarily eat zooplankton, small crustaceans, and insects in their freshwater habitat. In the ocean, they expand their diet to include smaller fish, shrimp, squid, and even eel.