- Fish: They primarily feed on various species of fish like herring, sardines, anchovies, cod, flounder, and capelin.
- Squid: Harbor seals consume different types of squid and cuttlefish.
- Crustaceans: They also feed on crustaceans such as shrimp, crabs, and krill.
- Octopus: Harbor seals occasionally eat octopus.
- Birds: Some harbor seals have been observed preying on seabirds like gulls and murres.
- Marine Mammals: Harbor seals have even been known to hunt other marine mammals, including young harbor porpoise and seals.
Their hunting strategies involve diving underwater and using their whiskers to detect prey. They may swim to depths of several hundred feet and can stay submerged for extended periods of time. Once they find their target, harbor seals use their sharp teeth to catch and subdue their prey.