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Harbour Seals

About AquaFacts: AquaFacts are a resource for students who are looking for information on the animals at the Aquarium or other Aquarium-related topics. Here, we’ve compiled some of the most frequently asked questions that we’ve received about harbour seals. The answers come from our biologists and from reputable sources that we reference at the end of this page. If you have a question about harbour seals that’s not addressed in this page or the references below, please feel free to email our librarian.

Harbour Seals

Questions & Answers

How do I know it's a harbour seal?

Harbour seals are found along the coast of the temperate Northern Hemisphere, often in coastal waters, estuaries and river systems. There are several subspecies, such as the Pacific harbour seal, Phoca vitulina richardsi, which inhabit the B.C. coast. The adult Pacific harbour seal may reach a length of 1.6 - 1.9 m and weigh from 60 - 120 kg, while ranging in colour from brownish to black with a speckled pattern.

harbour-seal-pups.jpgharbour-seal-pup-black.jpgharbour-seal-pup-white.jpg

Where are Pacific harbour seals found?

The Pacific harbour seal is found along the east coast of the Pacific, from Alaska to California. Other subspecies of harbour seals inhabit the North Atlantic and western North Pacific Oceans.

Are harbour seal populations endangered?

Between 1913 and 1970, the combination of a bounty implemented by Fisheries and Oceans Canada and extensive hunting of the harbour seal for its pelt lowered seal populations dramatically. Pacific harbour seal populations have recovered and are approaching historical records in B.C., with more than 127,000 individuals counted during a 1998 aerial survey.  Harbour seals are the most common of all the temperate-water seals.

What do harbour seals eat?

Preliminary studies analyzing harbour seal scat (feces) for bones and hard parts, indicate that the majority of their diet consists of small reef or shallow dwelling fishes including rockfishes, greenlings, smelt, perch, and some herring and flatfishes. In the Strait of Georgia, a large component of their diet is hake, a deep-water fish. Seasonally, harbour seals eat salmonids as these fishes enter and leave the rivers. Adult seals typically eat 3-5 kg of food per day.

How does the harbour seal reproduce?

Mating generally occurs in late spring or summer, shortly after the previous year’s pup has been weaned. Each male harbour seal will mate with several females during the breeding season. Competition for mates and copulation usually occur in the water. In B.C., the seal pup is born on tidal reefs or on beaches between late June and September, peaking in July and August.

How do harbour seals raise their pups?

Following birth, the pup is nursed and protected by its mother for four to six weeks. Nursing time corresponds to the ocean tide cycles, and may occur at low tide. A harbour seal pup can swim and dive shortly after birth but requires practice to increase its skill and endurance. The pup grows rapidly during its first month of life, gaining extra fat to help it survive while developing its hunting skills.

What senses do seals have?

Hearing and sight are highly developed in harbour seals. Large eyes, protected by oily “tears,” help the seal see in deep, dark waters. A harbour seal’s hearing is almost 14 times greater under water (160 kHz) than above the surface (12 kHz). Some scientists suspect that harbour seals may have the ability to echolocate. Whiskers can be extended forward to “feel” or inspect unfamiliar shapes and surfaces and are extremely important in low light situations. Blind harbour seals have been known to thrive in the wild. A harbour seal uses its sense of smell to locate a lost pup.

What are the differences between harbour seals and Steller sea lions?

Steller sea lions are larger and have longer front and back flippers than harbour seals. Sea lions are able to support themselves on their flippers and walk while seals use their belly to move on land in a motion called galumphing (they move like an inchworm). Steller sea lions are very noisy making throaty grunts and are territorial in their breeding ground; harbour seals are less vocal but can make a variety of  soft grunt like sounds.

How deep can a harbour seal dive?

Harbour seals can dive to 300 metres deep and an adult can hold its breath for up to 25 minutes.

What is the dive reflex?

When the seal’s face is submerged, it automatically holds its breath, its heartbeat slows by up to 90% and its blood circulation is reduced, except to the most vital organs, the heart and brain. This allows seals to stay under water for long periods.

What dangers do harbour seal populations face?

The harbour seal’s main predator is the killer whale, but they must also be on the lookout for some shark species and humans. They are protected against commercial exploitation, but is still hunted by some native populations and may be shot by fishermen. New threats to harbour seal populations are pollution and the reduction of their food stocks. Some seals die when they become entangled in fishermen’s nets, while parasites and disease are also an increasing threat to a growing population.

What is the Marine Mammal Rescue program?

The Vancouver Aquarium has rescued and rehabilitated marine mammals for over 50 years. The primary goal of the program is to rescue ill, injured, or abandoned marine mammals and rehabilitate them for release back into the ocean. The majority of animals accepted and rehabilitated each year are harbour seal pups. Learn more about the Marine Mammal Rescue Program here.

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Facts & References

Key Facts

  • Male harbour seals are called bulls, and females are called cows.
  • The harbour seal is considered a true, or earless seal, because it has no external earflaps as the sea lion does.
  • Harbour seals can sleep underwater. Their nervous system has an automatic shut-off mechanism that prevents them from breathing at inappropriate times. They will surface subconsciously to breathe.
  • Harbour seals can detect prey using nerves in their whiskers that sense pressure changes in the water.

 References

  1. Grace, Eric S. and Fred Bruemmer. 1991. Seals. Toronto: Key Porter Books.
  2. King, Judith E. 1983. Seals of the World. 2nd Ed. New York: Comstock Publishing.
  3. Gordon, David George. 1994. Seals and Sea Lions. Monterey Bay, Ca.: Monterey Bay Aquarium.
  4. Reeves, Randall R., Brent S. Stewart and Stephen Leatherwood. 1992. The Sierra Club Handbook of Seals and Sirenians. San Francisco: Sierra Club Books.
  5. Harbour seal. 2007. MarineBio.
  6. Harbour seal. 2001. Marine Mammal Centre

Permission is granted by the Vancouver Aquarium Marine Science Centre for classroom teachers to make copies for non-commercial use. This permission does not extend to copying for promotional purposes, creating new collective works, or resale.

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