Harbor seal
A gray, dog-snouted true seal that rests hauled out on rocks and floating glacier ice, bobbing in Alaska fjords with ear holes and no ear flaps.
Harbor seal at a glance
Phoca vitulina Harbor seal is HAR-bur seel; Phoca vitulina is FOH-kuh vit-yoo-LY-nuh
- Type
- Mammal · seal (pinniped)
- Diet
- Carnivore
- Size
- About as long as a bathtub (5 to 6 feet) and about as heavy as a washing machine (up to 285 pounds); pups weigh about 24 pounds at birth and gain more than a pound and a half a day on super-rich milk.
- Lifespan
- Around 25 to 30 years in the wild; some harbor seals have passed 30.
- Conservation
- Protected under the Marine Mammal Protection Act; not listed under the Endangered Species Act
Eats schooling fish, bottom fish, squid, crustaceans, shellfish
A harbor seal is an opportunistic hunter. It dives for schooling fish, bottom fish, squid, and crustaceans, and can eat up to 8 percent of its own body weight in a single day. It can sleep underwater, coming up for air about once every 30 minutes.
Should you worry?
Harbor seals are wild animals with strong jaws, and they bite to defend themselves. If a seal stares, fidgets, or slides into the water, you are too close. A mother may even abandon her pup if people crowd it. Stay at least 50 yards away, never feed or touch one, and never get between a mother and her pup, because disturbing a resting or nursing seal is illegal under federal marine-mammal law.
Out on the water in front of Aialik Glacier, the gray thing on the ice is easy to mistake for a broken-off rock. Then it lifts its head, then its hind flippers, and the whole body curls into a banana: forehead up, back feet up, belly pressed flat against the ice. That is a harbor seal resting, and the curl is the tell. Head and hind flippers up in the air keeps warmth in the middle, which matters for an animal that pulls itself out of near-freezing water to nap.
The nap itself is the strange part. A harbor seal does not need to find a bed. It can fall asleep in the water, drifting, and simply surface for a breath about once every half hour without waking up. Pups are born ready for the deep end, able to swim within minutes of birth, and a pup only a couple of days old can already hold its breath for two minutes on a shallow dive.
From a boat, you meet them at a respectful distance, and the distance is law. In Kenai Fjords, seals raise their pups on floating ice, and a vessel 100 yards away makes a resting seal 25 times more likely to jump into the water. NOAA’s guidance in those fjords is roughly 500 yards for boats and 50 yards for people on shore, and getting closer can actually cost a pup its life, because a mother that is repeatedly flushed may abandon it. Watch the banana curl, wonder at the underwater nap, and leave the ice exactly as you found it.
Did you know?
- Seen from the side, a resting harbor seal curls into a banana, head and hind flippers lifted, so it keeps warm while hauled out.
- A harbor seal pup can swim within minutes of being born, and a pup only two or three days old can already dive for two minutes.
- In Alaska's glacial fjords, seals rest and raise pups on floating ice, and a ship sitting 100 yards away makes them 25 times more likely to flush into the water, which is why boats keep their distance.
Common questions
Why do boats keep their distance from harbor seals?
Because it is the law and it keeps pups alive. The Marine Mammal Protection Act makes it illegal to harass a resting seal, and NOAA asks people to stay at least 50 yards away. In Alaska's glacial fjords the advice for boats is about 500 yards, because a ship 100 yards away makes a seal 25 times more likely to jump into the water.
What's the difference between a harbor seal and a Steller sea lion?
Steller sea lions are much bigger, have visible ear flaps, bark loudly, and can walk by rotating their hind flippers under their bodies. Harbor seals are smaller, have only ear holes, stay quiet, and wiggle on their bellies. In Kenai Fjords you see both, so the ears and the size are the tell.
What do harbor seals eat?
Whatever swims or crawls nearby: small schooling fish, bottom fish, squid, crabs, and other crustaceans. A hungry harbor seal can eat up to 8 percent of its own body weight in one day.
Are harbor seals endangered?
Not as a species. They are protected by the Marine Mammal Protection Act, and many populations are stable or growing. Alaska's numbers dropped sharply in the 1980s, though the seals of Aialik Bay near Kenai Fjords fell from more than 1,600 to about 200.