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The Science Behind Harbor Seal Monitoring

February 11, 2013

Harbor seals in Puget Sound have had a challenging history—they were once hunted because they were considered competitors with fishermen. By the early 1970s, only about two to three thousand harbor seals remained in Washington. But in 1972, the Marine Mammal Protection Act made it illegal to kill any marine mammals. The Act, which celebrates its 40th anniversary this year, helped the harbor seal population recover—scientists counted 30,000 seals in their last full census.

So what's it like to study harbor seals in Puget Sound? NOAA Fisheries wildlife biologist Harriet Huber can tell you. From a station 30 feet up in the air, Huber observes the seals and their markings for identification. The markings help her and other scientists collect long-term data on how long harbor seals live, when females start giving birth, survival rates of each age class, and more broadly, the population status today. 

Monitoring the harbor seal population is far from over. NOAA scientists will continue tracking their population and habits because they also indicate the health of the Puget Sound ecosystem in which they live.

Check out the harbor seal video below and to see more cool videos, visit the NOAA Fisheries YouTube channel.



Did You Know? Harbor Seals
  • Harbor seal pups can swim at birth. Like all marine mammals, harbor seals are protected under the Marine Mammal Protection Act.
  • When seals are only 2-3 days old, they can dive for up to 2 minutes.
  • Harbor seals are found all along the U.S. west coast up to Alaska, and on the U.S. east coast from New York state to Maine.
  • Harbor seals can weigh up to 245 pounds and grow to be approximately 6 feet long.
  • Harbor seals are part of the "true seal" family, Phocidae. True seals lack external ear flaps and have short forelimbs that result in limited locomotion on land.
  • Harbor seals often rest on land in a banana-like fashion—with their head and rear flippers elevated.