Harbor Seal
Protected Status
Quick Facts
About The Species
Harbor seals are one of the most common marine mammals along the U.S. West and East Coasts. They are commonly seen resting on rocks and beaches along the coast and on floating ice in glacial fjords with their head and rear flippers elevated in a “banana-like” position.
State-financed bounty hunters once hunted harbor seals in Washington and Oregon because they were considered competitors of fishermen. This hunting program ended in 1960.
Harbor seals, like all marine mammals, are protected under the Marine Mammal Protection Act.
Status
In the United States, NOAA Fisheries has identified five stocks of harbor seals: Alaska, California, Oregon-Washington coastal, Washington inland, and western North Atlantic. Each stock has experienced different population trends over the past 30 years. Along the West Coast, stocks are stable and some are even increasing. The population in New England is also increasing. Breeding and molting colonies can number in the thousands in these areas.
Most stocks in Alaska are also stable or slightly increasing, but the Gulf of Alaska stock is small today compared to the 1970s and 1980s. This stock may be continuing to decline.
Learn more about our estimates for population size in our stock assessment reports
Protected Status
MMPA Protected
- Throughout Its Range
Appearance
Harbor seals are part of the true seal family. All true seals have short forelimbs, or flippers. They also lack external ear flaps and instead have a small hole (opening to the ear canal) on either side of their head.
Harbor seals weigh up to 285 pounds and measure up to 6 feet in length. Males are slightly larger than females, and seals in Alaska and the Pacific Ocean are generally larger than those found in the Atlantic Ocean.
Harbor seals have short, dog-like snouts. The color of each seal’s fur varies but there are two basic patterns: light tan, silver, or blue-gray with dark speckling or spots, or a dark background with light rings.
Behavior and Diet
Harbor seals haul out (rest) on rocks, reefs, beaches, and drifting glacial ice at night and during the day. They haul out to regulate their body temperature, molt, interact with other seals, give birth, and raise their pups. They also haul out in groups to avoid predators and spend less time being watchful for predators than those that haul out alone.
Harbor seal pelvic bones are fused, preventing them from moving their hind flippers under their pelvis to walk on land. Instead, they move by undulating in a caterpillar-like motion. This does not mean they are injured.
Harbor seal pups can swim at birth. They can also dive for up to 2 minutes when they are only 2 to 3 days old. Mother harbor seals raise their pups in nurseries—groups of mothers and their young—that help protect the seals from predators.
The harbor seal’s diet consists mainly of fish, shellfish, and crustaceans. Harbor seals complete both shallow and deep dives while hunting depending on the availability of prey. They can sleep underwater and come up for air once every 30 minutes.
Where They Live
Harbor seals live in temperate coastal habitats along the northern coasts of North America, Europe, and Asia. They occur on the U.S East and West coasts. On the East Coast, harbor seals are found from the Canadian Arctic to New York and occasionally as far south as the Carolinas. Harbor seals are found all along the West Coast of North America, from California to the Bering Sea. They have long been considered non-migratory and typically stay within 15 to 31 miles of home, but telemetry data have shown they sometimes travel 62 to 249 miles from their tagging location.
Lifespan & Reproduction
Harbor seals reach sexual maturity between 3 and 7 years old and mate in the water. While females usually give birth during the spring and summer, the pupping season varies by location. Pups are born earlier in the south than in the north. The only exception is harbor seals in the inland waters of Washington, which are born 2 months later than seals along the coast of Washington.
Females are pregnant for about 10 months. Pups weight about 24 pounds at birth and are ready to swim within minutes. They are nursed for 4 to 6 weeks on milk that is 50 percent fat. Like adults, seal pups haul out on shore to rest and regulate their body temperature. Mothers and pups group together in nurseries to protect themselves from predators.
Threats
Entanglement
Harbor seals can become entangled in fishing gear and other types of marine debris, either swimming off with the gear attached or becoming anchored. They can become entangled in many different gear types, including gillnets, trawls, purse seines, or weirs. Once entangled, seals may drown if they cannot reach the surface to breathe, or they may drag and swim with attached gear for long distances, ultimately resulting in fatigue, compromised feeding ability, or severe injury, which may lead to reduced reproductive success and death.
Illegal Feeding and Harassment
Illegal feeding of harbor seals can lead to many problems including habituation, aggression, negative impacts to fisheries, entanglement, injury, and death. Harassment, including repeated exposure to vessel traffic and disturbance, can degrade important nursery areas for harbor seals. Increased vessel traffic can also cause altered behavior, increased energetic expenditures, and increased exposure to stress. In Alaska, vessel traffic can also displace seals from ice floes, putting pups at risk from increased time spent in cold water and separated from their mothers.
Learn more about the Alaska harbor seal approach guidelines in glacial fjords (PDF, 2 pages)
Habitat Degradation
Harbor seals are susceptible to habitat destruction and degradation. This can range from physical barriers that limit their access to important migration, breeding, feeding, or pupping areas, to activities that destroy or degrade their habitats. Physical barriers may include shoreline and offshore development (oil and gas exploration, dredging, pile driving) and increased boat traffic. Recreational use of marine areas, including resort development and increased boat traffic, may displace seals that would normally use those areas.
Chemical Contaminants
Contaminants enter ocean waters from many sources, including oil and gas development, wastewater discharges, urban runoff, and other industrial processes. Once in the environment, these substances move up the food chain and accumulate in predators near the top of the food chain such as harbor seals. Because of their blubber stores, harbor seals accumulate these contaminants in their bodies, threatening their immune and reproductive systems.
Vessel Collisions
Inadvertent vessel collisions can injure or kill harbor seals. Harbor seals are vulnerable to vessel collisions throughout their range, but the risk is much higher in some coastal areas with heavy ship traffic.
Scientific Classification
Kingdom | Animalia | Phylum | Chordata | Class | Mammalia | Order | Carnivora | Family | Phocidae | Genus | Phoca | Species | vitulina |
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What We Do
Conservation & Management
NOAA Fisheries is committed to the protection of harbor seals. Targeted management actions taken to secure protections for these seals include:
- Reducing contaminants.
- Minimizing human interactions and associated injury and mortality through various public outreach efforts.
- Reducing vessel collisions and disturbance through educational materials.
- Overseeing marine mammal health and stranding response.
- Working with Alaska Native organizations to conserve and promote the sustained health of harbor seals
- Implementing oil spill response plans in the event of a spill
Science
Our research projects have discovered new aspects of harbor seal biology, behavior, and ecology and have helped us better understand the challenges that all harbor seals face. Our work includes:
- Satellite tagging.
- Observational studies.
- Stock assessments.
- Monitoring population abundance and distribution.
How You Can Help
Report Marine Life in Distress
Report a sick, injured, entangled, stranded, or dead animal to make sure professional responders and scientists know about it and can take appropriate action. Numerous organizations around the country are trained and ready to respond. Never approach or try to save an injured or entangled animal yourself—it can be dangerous to both the animal and you.
Learn who you should contact when you encounter a stranded or injured marine animal >
Report a Violation
Call the NOAA Fisheries Enforcement Hotline at (800) 853-1964 to report a federal marine resource violation. This hotline is available 24 hours a day, 7 days a week for anyone in the United States.
You may also contact your closest NOAA Office of Law Enforcement field during regular business hours.
Keep Your Distance
Be responsible when viewing marine life in the wild. Observe all seals and sea lions from a safe distance of at least 50 yards and limit your time spent observing to 30 minutes or less.
Featured News
Related Species
In the Spotlight
Management Overview
Harbor seals are protected under the Marine Mammal Protection Act. In the United States, NOAA Fisheries works to protect all populations of harbor seals.
Conservation Efforts
NOAA Fisheries is committed to the protection of harbor seals. Targeted management actions taken to secure protections for these seals include:
Reducing Contaminants
Harbor seals are vulnerable to chemical contaminants because they are near the top of the food chain. NOAA's Damage Assessment, Remediation, and Restoration Program, which cleans up existing contamination, has several active projects in the Pacific Northwest and California.
Educating the Public
Some harbor seals haul out in public areas. Together with the West Coast Marine Mammal Stranding Network, we have developed programs to educate the public about how to “Share the Shore” with harbor seals, as well as prohibitions against capturing, harming, or harassing them.
Frequently asked questions about harbor seal pups (PDF, 2 pages)
Learn more about sharing the shore with harbor seals and harbor seal pups (PDF, 2 pages)
Implementing Oil Spill Response Plans in the Event of a Spill
Harbor seals are at risk of harm in the event of an oil spill. To reduce the risk of a spill, Washington’s Department of Ecology created the Spill Prevention, Preparedness, and Response Program. To minimize the effect of a potential spill on harbor seals, NOAA developed the Marine Mammal Oil Spill Response Guidelines.
Overseeing Marine Mammal Health and Stranding Response
We work with volunteer networks in all coastal states to respond to marine mammal strandings including large whales. When stranded animals are found alive, NOAA Fisheries and our partners assess the animal’s health. When stranded animals are found dead, our scientists work to understand and investigate the cause of death. Although the cause often remains unknown, scientists can sometimes identify strandings due to disease, harmful algal blooms, vessel strikes, fishing gear entanglements, pollution exposure, and underwater noise. Some strandings can serve as indicators of ocean health, giving insight into larger environmental issues that may also have implications for human health and welfare.
Learn more about the Marine Mammal Health and Stranding Response Program
Marine Mammal Unusual Mortality Events
There is an ongoing Unusual Mortality Event for Harbor Seal. Under the Marine Mammal Protection Act, an unusual mortality event (UME) is defined as "a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response." To understand the health of marine mammal populations, scientists study unusual mortality events.
Get information on active and past UMEs
Get an overview of marine mammal UMEs
Reducing Vessel Strikes
Collisions between harbor seals and vessels can injure or kill seals. The most effective way to reduce vessel disturbance is for vessels to stay away from seals. If this is not possible, the second-best option is for vessels to follow voluntary approach guidelines.
In Alaska, for example, we have issued voluntary approach guidelines to reduce the disturbance of harbor seals in glacial fjords. Tidewater glacier areas provide essential habitat for harbor seals, especially when nursing pups and molting. Scientific research indicated that previous marine mammal approach measures (voluntary guidelines to avoid approaching within 100 yards) were not adequately protecting harbor seals from disturbance in Alaska’s glacial fjords. Because glaciers in Alaska are experiencing unprecedented rates of ice loss, harbor seals are already coping with reduced ice cover at some tidewater glaciers, which makes them more sensitive to other impacts.
For these reasons, NOAA developed the Alaska Harbor Seal Approach Guidelines in Glacial Fjords. The guidelines suggest that all vessels (from kayaks to cruise ships) should:
- Strive to maintain 500 yards from seals without compromising safe navigation.
- Make an approach plan to avoid surprising seals.
- Be equally as cautious to reduce disturbance when departing the fjord as arriving.
- Minimize wake, avoid abrupt changes in course or engine pitch, and avoid loud noises (such as collisions with ice) near seals.
- Try to avoid traveling through thick ice, as the absence of seals on the ice does not mean the area is not being used.
- Time visits when feasible to minimize overlap with the peak numbers of seals hauled out midday and minimize the chances of disturbance.
Learn more about voluntary approach guidelines
Learn more about voluntary approach guideline FAQs
Providing Sustainable Harbor Seal Subsistence
As the primary consumptive users of Alaska harbor seals, Alaska Natives are committed to a long-term, sustainable harvest of harbor seals for food and handicrafts. Their long history of self-regulation coupled with their rich oral tradition and day-to-day contact with Alaska harbor seals gives them special insights into and knowledge of this important marine mammal.
Learn more about the subsistence harvest of harbor seals in Alaska
Key Actions and Documents
Incidental Take Authorization: Ørsted Wind Power North America, LLC Site Characterization Survey off New York to Massachusetts
Incidental Take Authorization: U.S. Navy Transit Protection Program Pier and Support Facilities Project at Naval Base Kitsap Bangor, Washington
Incidental Take Authorization: Lamont-Doherty Earth Observatory Marine Geophysical Survey in the Aleutian Islands
Incidental Take Authorization: Renewal of U.S. Fish and Wildlife Service Eastern Massachusetts National Wildlife Refuge Complex Research, Monitoring,
More Information
- Report a Stranding or an Injured Marine Mammal
- Alaska Harbor Seal Approach Guidelines in Glacial Fjords
- Share the Shore: Harbor Seals
- Share the Shore: Harbor Seal Pups
- Alaska Marine Mammal Viewing Guidelines and Regulations
- Marine Mammal Permits and Authorizations
- Marine Life Viewing Guidelines
- Harbor Seal Contacts
Science Overview
NOAA Fisheries conducts various research activities on the biology, behavior, and ecology of harbor seals. The results of this research are used to inform management decisions for this species.
Satellite Tagging
In the Aleutian Islands of Alaska, NOAA Fisheries scientists and their collaborators track location data from satellite tags deployed on harbor seals to determine their movement and distribution, as well as their diving and haul-out behavior.
Learn more about the movement and dive behavior of harbor seals in the Aleutian Islands
Observational Studies
In Washington, NOAA Fisheries conducts observational studies to understand the life history and population dynamics of harbor seals in Puget Sound. Our scientists have continually monitored this population since 1993.
Stock Assessments
Determining the size of harbor seal populations helps resource managers determine the success of conservation measures. Our scientists collect population information and present the data in annual stock assessment reports.
Monitoring Population Abundance and Distribution
Scientists observe harbor seals to record their numbers and distribution. By comparing numbers collected over multiple years, scientists can look for trends—i.e., whether the population is increasing, decreasing, or remaining stable during a given period.
Alaska Fisheries Science Center Harbor Seal Research
Find out more about what our scientists are learning about harbor seals in Alaska
Documents
Cook Inlet & Kodiak Marine Mammal Disaster Response Guidelines and Appendices
Cook Inlet and Kodiak Marine Mammal Disaster Response Guidelines (CIKMMDRG) address disaster…
Copper River Delta Carcass Surveys: Annual Reports
Biologists conducted survey flights of the shifting sand shoals of the Copper River Delta to search…
Scientific Evaluation of the Distinctness of Harbor Seals (Phoca vitulina) in Iliamna Lake
Review of relevant background information about harbor seal biology and scientific and local…
Incidental Takes and Interactions of Marine Mammals and Birds in Districts 6, 7 and 8 of the Southeast Alaska Salmon Drift Gillnet Fishery, 2012 and 2013
Marine Mammal Observer Program observations of the Southeast Alaska salmon drift gillnet fishery.
Data & Maps
Alaska Harbor Seal Data Sets
The Alaska Fisheries Science Center's harbor seal data sets are available on the NOAA Fisheries…
Research
Alaska Marine Mammal Field Work
NOAA Fisheries Alaska Fisheries Science Center (AFSC) and National Oceanic & Atmospheric Administration (NOAA) conduct research on marine mammals off the coasts of Alaska, Washington, Oregon, and California.
2020 Alaska Marine Mammal Field Work Surveys Flyer
The Alaska Fisheries Science Center of the National Marine Fisheries Service, National Oceanic &…
Alaska Marine Mammal Observer Program
NOAA Fisheries is not operating the Alaska Marine Mammal Observer Program (AMMOP) due to a lack of available resources to fund additional observations of the southeast Alaska salmon drift gillnet fishery. We will reassess future AMMOP activities as…
Studies of Harbor Seals Using Glacial Ice in Disenchantment Bay, Alaska, 2016-2017
This summary will provide an update on NOAA-AFSC’s latest research on seal-vessel interactions…
Outreach & Education
Do Not Shoot Seals and Sea Lions Video
Don't harm your fishery for all. Shooting seals and sea lions is against the law.
Alaska Marine Mammal Viewing Guidelines and Regulations Booklet
Booklet summarizing Alaska humpback whale approach regulations, viewing guidelines for sea lions,…
Alaska Harbor Seal Approach Guidelines in Glacial Fjords
This brochure provides guidelines to inform vessel operators and the public how to be mindful of…