What Do Orcas Eat? Orca Diet and Hunting by Ecotype

Orca diet at a glance

Orcas have the broadest diet of any whale, yet no single orca eats everything. Scientists divide them into ecotypes, populations that differ in prey, hunting style, calls and genetics.

Fish-eating orcas: salmon, herring and tuna

The best-studied fish eaters are the resident orcas of the northeastern Pacific. A long-term study in British Columbia found that salmon made up about 96% of their summer diet, and that they chose the largest, fattest species, Chinook salmon, far more often than its abundance would suggest. Residents usually hunt salmon alone or in small groups, chasing a fish down with bursts of speed and echolocation, and they sometimes share the catch with family members, especially mothers with their offspring.

In Norway and Iceland, orcas follow the huge herring shoals. They use a teamwork method called carousel feeding: the whales circle a school, blow bubbles and flash their white bellies to herd the fish into a tight ball, then slap it with their tails to stun them, and pick off the dazed fish one by one. Off Spain and Portugal, the small Iberian population follows Atlantic bluefin tuna, sometimes chasing them to exhaustion and sometimes taking them from fishing lines. Around Antarctica, the small Type C orcas of the Ross Sea feed on Antarctic toothfish.

Mammal hunters: seals, sea lions, porpoises and dolphins

Bigg’s orcas, named after the Canadian scientist Michael Bigg, share the same coasts as residents but hunt marine mammals. Harbor seals are their most common prey, followed by sea lions, harbor and Dall’s porpoises and Pacific white-sided dolphins. Because seals and porpoises can hear orca calls, Bigg’s orcas hunt in near silence and usually travel in small groups of two to six.

Different populations have invented remarkable techniques:

• Wave-washing. In Antarctica, Type B orcas spot a seal resting on an ice floe, then swim side by side toward it to make a wave that washes the seal into the water.
• Intentional stranding. At Península Valdés in Argentina and the Crozet Islands in the southern Indian Ocean, orcas rush onto steep beaches to snatch sea lion or elephant seal pups, then wriggle back into the sea. Young orcas take years to learn this risky skill, and mothers help them practice.
• Ramming and tail strikes. To avoid being bitten, orcas often stun large seals and sea lions with tail slaps or ramming before eating them.

Do orcas hunt whales?

Yes, and that is how they earned the name killer whale. Antarctic Type A orcas eat mainly minke whales. Along the North Pacific coast, Bigg’s orcas ambush gray whale calves as they migrate north with their mothers in spring, and orcas also attack humpback calves. In 2019, researchers off Western Australia witnessed orcas killing blue whales for the first time.

Hunting a large whale takes teamwork and stamina. The orcas chase the whale for a long time, bite at its flippers and tail, and try to keep it from surfacing to breathe. Large whales defend themselves: sperm whales form a protective circle around their calves, and humpbacks sometimes charge into orca attacks, even when the target is another species.

Sharks and rays

Orcas off New Zealand often hunt stingrays and eagle rays in shallow water, pinning them to the seabed, and also take sharks. Offshore orcas in the North Pacific have heavily worn teeth, probably from eating rough-skinned sharks.

The most famous shark hunters live off South Africa. Since 2017, a pair of male orcas known as Port and Starboard, sometimes joined by others, has killed several great white sharks and eaten their energy-rich livers. Orcas have also killed white sharks off California and in the Gulf of California. They seem to flip sharks upside down, which puts them into a trance-like state called tonic immobility. How the two predators compare is explained in orca vs great white shark.

Seabirds, turtles and surprises

Orcas also take seabirds, including several kinds of penguins around Antarctica, though they often kill birds without eating them. Sea turtles, squid and octopus appear in the diet of some populations. Along the Pacific coast of North America, orcas have occasionally caught moose swimming between islands.

Orcas can also be opportunists. In Alaska and elsewhere, some have learned to strip fish from fishing lines as they are hauled in, and they have quickly adapted to tricks fishers use to stop them.

How much does an orca eat?

The amount depends on the whale’s size and the energy in its prey. Published estimates for adult orcas range from about 45 kg (100 lb) to more than 200 kg (440 lb) of food a day. Seals and other fat-rich mammals provide far more energy per kilogram than most fish, which is one reason mammal hunters can live in small groups that hunt less often.

Why orcas stick to their own menu

Food habits are learned, not instinct. Calves learn what to hunt from their mothers and grandmothers, and these traditions last for generations. Residents and Bigg’s orcas share the same waters, yet residents do not switch to seals even when salmon is scarce. This loyalty to traditional prey is part of what makes orcas so fascinating, but it is also a danger: the endangered Southern Residents of Washington and British Columbia depend on dwindling Chinook salmon, and their food supply is their greatest threat. Read more about the species in our orca profile.