The question of whether dolphins eat seals has a complex answer. While the majority of the nearly forty dolphin species focus on smaller prey, a few populations, particularly the largest species, regularly include seals and sea lions in their diet. The answer depends entirely on the specific dolphin species and its geographic location.
The Typical Diet of Oceanic Dolphins
Most species of oceanic dolphins are primarily fish-eaters (piscivory), with their diet consisting mainly of small schooling fish, squid, and crustaceans. Prey selection is heavily influenced by the dolphin’s habitat and geographic location. For instance, dolphins inhabiting coastal areas often target species like mullet and sea trout, while those in the open ocean consume a greater proportion of squid and deep-sea fish.
Dolphins employ a highly refined sensory system called echolocation to locate and capture their prey, emitting high-frequency clicks and interpreting the returning echoes. Many species also engage in cooperative hunting behaviors, working together to corral schools of fish into dense “bait balls.” Some coastal populations even use their tails to create rings of mud that stun or force fish out of the water.
Documented Cases of Non-Orca Dolphin Predation on Seals
Excluding the largest dolphin species, direct predation on seals by smaller dolphins is rare and opportunistic, though aggressive interactions have been documented. Common bottlenose dolphins, for example, have been observed engaging in violent, non-feeding attacks on other marine mammals, most notably harbor porpoises. This behavior often results in the porpoises’ death from blunt trauma and has been seen in locations like the United Kingdom and California.
While the primary victims of this non-predatory aggression are smaller cetaceans, the forceful ramming and striking techniques used could also be lethal to seal pups or weakened adult seals. Researchers suggest this aggression could be misplaced infanticide, practice for acquiring hunting skills, or a manifestation of social dominance, particularly among young male dolphins. Crucially, in the few instances where non-Orca dolphins have been documented killing other marine mammals, the victims were rarely consumed, differentiating this behavior from true predation driven by hunger.
Killer Whales: The Specialized Marine Mammal Predators
The most definitive answer to the question of dolphins eating seals lies with the largest member of the oceanic dolphin family, the killer whale, or Orca (Orcinus orca). Orcas are apex predators whose diet is highly specialized, and certain populations regularly and systematically hunt seals, sea lions, and other marine mammals. Scientists classify orcas into distinct ecotypes that specialize in different diets and exhibit unique hunting cultures.
The “Transient” or “Bigg’s” ecotype of orca, found along the west coast of North America, focuses almost exclusively on marine mammals, including harbor seals and sea lions. These orcas operate in small, stealthy groups, often remaining silent to avoid detection by their prey. Similarly, the “Pack Ice” orcas of the Antarctic have developed a highly coordinated strategy called “wave-washing,” where they create a powerful, synchronized wave to dislodge seals resting on ice floes into the water.
These specialized mammal-eating orca ecotypes demonstrate that seal consumption is a fundamental and learned part of their feeding ecology. This contrasts sharply with the fish-focused diet of most other dolphins and the non-consumptive aggression sometimes displayed by smaller species. The sheer size and cooperative hunting strategies of orcas make them the only dolphin species for whom seals are a regular and primary food source.