Creature Feature: Harbor Seals

By Lizzy Ashley

If you have lived in or visited the Salish Sea, you have probably seen a harbor seal. Although harbor seals are the region’s most common marine mammal, it never gets old seeing one zoom after a fish or peacefully sleep on a rocky shore!

Spotted Sea-Caterpillars

The harbor seal’s scientific name is Phoca vitulina (pronounced foh-kah vitu-leena). It’s easy to remember this name if you know that harbor seals are part of the Phocidae or “true seal” family of pinnipeds (a group of carnivorous marine mammals). Ever wondered how to tell apart the pinniped families Otariidae (sea lions) and Phocidae (seals)? Seals lack external ear flaps, cannot rotate their hind (back) flippers forward, and use their hind flippers for forward motion underwater. Finally, seals aren’t very good at moving on land compared to their sea lion relatives - they almost look like giant caterpillars bouncing along the ground!

Pacific harbor seals (Phoca vitulina richardii) can be identified by their unique pelage (coat) ranging from pale silver to dark gray with many spots, rings, and splotches. Harbor seals are fairly small seals, reaching 4-5 feet in length and weighing 130-155 lbs. A healthy harbor seal will look fairly round in appearance due to a thick, warm blubber layer. In the Salish Sea, you can see harbor seals swimming or hauled-out on islands, beaches, rocks, reefs, or docks. They haul out (come ashore) to rest, avoid predators, give birth and nurse young, socialize, and annually molt their pelage. Haul-out sites are so important to harbor seals that they typically stay pretty close to one site for their entire lives. Scientists call this “high site fidelity.”

Chubmarines

By Bob Friel

Harbor seals eat over 60 different species of fish and invertebrates, from rockfish and herring to squid and dungeness crab. Harbor seals are called “generalists” due to these not-so-picky eating habits. How do they manage to catch so many different critters? Harbor seals can shoot out their flexible necks quickly to lunge after fish. They are also excellent divers! Harbor seals in the San Juan Islands, for example, can dive up to 100 meters deep for around 6 minutes. They’re speedy - harbor seals experience 5 times less drag (the force that opposes movement) than human swimmers due to their sleek, streamlined bodies. To spend more time at depth, their heart rate slows down, and blood circulation to the limbs is reduced to conserve oxygen for the brain and heart. A harbor seal spends about 100 hours a week diving - time mostly spent hunting for prey!

Pup-a-palooza

Summer in the Salish Sea means sunshine, beaches, boats... and for harbor seals, pups! Harbor seal pupping season is sometime between June and October each year depending on where you are in the Salish Sea. Female harbor seals give birth to one pup at a time (usually) after 9-11 months of pregnancy. For around 30 days, mom provides fatty, rich milk for her pup so it can gain weight quickly. Sometimes she will leave her pup on shore unattended for 1-2 days while she forages to restore energy. So, if you see a pup alone on a beach, don’t panic! When this happens, it is important to keep people and dogs at least 100 yards away so that mom will feel it is safe to come retrieve her pup. It’s also good to call a local marine mammal stranding network so they can be aware of the situation. After the month-long nursing period, mom will leave, and pups must use the skills they’ve gained practicing dives with mom to forage on their own!

Comeback Story

Harbor seals live in coastal, rocky areas all over the world. We are lucky to live alongside 50,000 Pacific harbor seals year-round in the Salish Sea - that’s 3 seals per km2 of ocean! Unfortunately, harbor seals weren’t always abundant here. Before the U.S. government passed the Marine Mammal Protection Act of 1972, which outlawed killing marine mammals, harbor seals were hunted in the Pacific Northwest. Thanks to changed laws and attitudes, harbor seal populations have bounced back at an explosive rate! Even though their numbers are strong now, harbor seals are threatened by issues like disease, contaminants, and negative interactions with humans. To help protect harbor seals, we can avoid approaching or feeding them, educate people about their story, and support efforts to restore fish populations and habitat in the Salish Sea.