What Do Salmon Eat?

Baby salmon called fry eat tiny aquatic insects, zooplankton, and other micro-organisms when they first hatch. As they grow, young salmon eat larger insects like mayfly larvae and midges. Small fish eggs and crustacean larvae become important foods for growing fry. Young salmon hide under rocks in rivers and wait for food to drift past in the current. They eat insects that fall into the water from trees and plants along riverbanks. Freshwater shrimp and other invertebrates provide crucial nutrition during their river phase. Young salmon grow quickly on this diet for their first one to three years in freshwater. Once they grow large enough to move downstream toward the ocean, they begin eating slightly larger prey. Visit /wildlife to learn about other river-dwelling animals and their feeding habits.

When salmon move into the ocean, their diet changes dramatically from small invertebrates to ocean fish. Adult salmon hunt small fish including sand eels, herring, and other schooling fish species. Northern sand lance and Pacific sand lance are favorite prey in northern waters and feeding grounds. They eat Pacific chub mackerel and cod when available in their ocean migrations. Squid including the opalescent inshore squid provide important nutrition and fatty acids for growth. Salmon grow rapidly in the ocean because prey is abundant and hunting is very productive. Some salmon travel thousands of miles in the ocean, following fish schools and eating constantly. Eulachon and other small fish with high fat content are particularly valuable foods for energy storage. Ocean salmon can grow several kilograms per year on this rich diet of abundant prey. Check /wildlife/washington/salmon for information about salmon species in Pacific waters.

Chinook salmon, the largest species, eat bigger fish than smaller salmon species do. Pink and chum salmon feed on smaller plankton and small fish in different proportions than other species. Sockeye salmon eat plankton and small fish in different proportions than other Pacific salmon species. Atlantic salmon in their native eastern waters eat different fish than Pacific salmon do. Alaska salmon encounter different prey than salmon in Washington or Oregon waters. Check /wildlife/alaska/salmon for details about northern salmon diets and species. Southern salmon populations feed on different herring and rockfish species than northern groups. Ocean currents and water temperature affect which fish species thrive in each area. Water depth and seasonal changes in food availability shape each population's diet patterns. Regional differences mean salmon populations have adapted to eating what is available locally year-round.

Salmon are active hunters that chase fish through open water with speed and determination. They use speed and agility to catch prey quickly before it escapes. Salmon leap and thrash through schools of smaller fish to confuse and isolate individual targets. Some salmon species are visual hunters that rely on sight to find prey in the water column. Salmon often work together, herding fish schools into tighter groups before feeding on them. In rivers, salmon hold position behind rocks and grab food drifting downstream in the current. Ocean salmon may travel hundreds of kilometers following food sources and migrating prey. They learn where to find food and remember productive feeding areas and seasonal changes. Salmon feed heavily during ocean phases to build energy reserves for later use. These reserves are crucial for surviving the river migration back to spawning grounds where they stop eating completely.

Salmon eggs contain a yolk sac that feeds them for their first weeks of life after hatching. Once the yolk sac is consumed, young salmon must catch live food to survive. Newly feeding fry are very vulnerable and prefer tiny insects and zooplankton in their environment. As fry grow, they eat progressively larger insects and crustaceans becoming more effective hunters. Young salmon practice hunting on small invertebrates before moving to larger prey items. They spend their river phase eating constantly to grow and prepare for migration. Some salmon species leave rivers after just a few months of growth and development. Others stay in rivers for several years while growing and eating before migration. The river diet is low in fat compared to ocean food sources available later. Salmon that migrate to the ocean gain weight much faster than those staying in rivers for extended periods.

As salmon enter rivers to return to birthplace streams, they completely stop eating and cease feeding. Their bodies are loaded with energy stored during ocean phases of their life. Salmon rely entirely on internal reserves for their river trip and spawning season. Some salmon travel hundreds of kilometers upstream without eating any food. They lose weight and condition during this critical period of upstream migration. Their digestive systems actually shrink and stop functioning during the entire migration. River conditions like waterfalls and fast current slow their progress up river. Salmon must navigate to their home streams using memory and environmental cues and instinct. Predators like bears wait at popular fishing spots to catch migrating salmon before spawning. Salmon that reach spawning areas have used most of their stored energy for the trip. After spawning, salmon no longer eat and soon die, their bodies returning nutrients to ecosystems.

Salmon are predatory fish, but they are also prey for many larger animals and predators. Trout eat similar foods to young salmon and occupy similar habitats in rivers and streams. Arctic char also hunt insects and small fish in cold waters of northern regions. Char species can coexist with salmon by eating slightly different sizes of prey and food items. Larger predatory fish like pike and perch eat salmon eggs and young fish in freshwater. Seals and sea lions hunt adult salmon in ocean and river environments where they congregate. Bears and birds focus on salmon during spawning season when they are most vulnerable. Dolphins also hunt adult salmon in coastal waters following migration routes. Salmon serve as a food link, consuming plankton and small fish while being consumed by larger predators. This places them in the middle of complex food webs and ecological relationships. Learn more at /wildlife/washington/salmon for specific information about Pacific salmon species and ecosystems.