Dolphins are marine mammals with diverse dietary habits across the world’s oceans. Whether dolphins consume salmon depends entirely on the specific population and its location. While most smaller dolphin species have generalist diets of schooling fish and squid, one group relies heavily on salmon as a primary food source.
The Primary Salmon Predator
The most prominent dolphin species known for consuming large amounts of salmon is the Killer Whale, or Orca. Not all orcas eat salmon, as different populations, or “ecotypes,” have distinct, culturally passed-down diets. Specifically, the resident orca populations of the Pacific Northwest are piscivorous, meaning they feed exclusively on fish.
Their diet is highly specialized, focusing intensely on salmon, which makes up roughly 90% of their prey. They primarily target Chinook salmon because these fish are the largest and most calorie-rich Pacific salmon species. This specialized diet means resident orcas are acoustically active hunters, using echolocation to find their prey. The survival of these resident orca pods is directly tied to the abundance and size of the Chinook salmon runs.
Opportunistic Feeding by Other Dolphin Species
Most smaller dolphin species do not rely on salmon as a dietary staple. Coastal dolphins, such as the Bottlenose dolphin, are opportunistic feeders, consuming a varied diet of fish, squid, and crustaceans. However, certain populations will readily target salmon when the fish are seasonally available.
Bottlenose dolphins in the Moray Firth off the coast of Scotland, for instance, favor Atlantic salmon during spring and summer migrations toward spawning grounds. This seasonal consumption contrasts sharply with the orca’s consistent, year-round targeting of Pacific salmon. Local availability drives the dietary choices of these generalist dolphin species.
Geographic Areas of Interaction
The predator-prey relationship is most concentrated in the North Pacific Ocean, particularly within the Salish Sea and adjacent coastal waters. This region provides the necessary overlap between the year-round habitat of resident orca populations and the migratory routes of Chinook salmon. The availability of salmon is a major factor in the overall health and stability of these specific orca communities.
A decline in the number and size of these large salmon has been observed, forcing resident orcas to search over wider areas for food. This resource scarcity creates a conservation challenge, as the fate of the endangered resident orcas is inextricably linked to the recovery of the salmon populations. Seasonal consumption by Bottlenose dolphins occurs in coastal areas like the North Atlantic, where salmon runs provide a temporary, high-value food source during migration.