Northern Elephant Seal
About the Species
The northern elephant seal is the largest of the “true” seal in the Northern Hemisphere. Adult males use their large, inflatable noses during the winter breeding season to resonate sound when vocally threatening each other. The largest colonies of northern elephant seals are found off southern California in the Channel Islands. They have one of the longest migrations of any mammal; some have been recorded traveling over 13,000 miles roundtrip.
Northern elephant seals were once thought to be extinct due to commercial sealing in the 1800s. Populations of northern elephant seals in the U.S. and Mexico were all originally derived from a few hundred individuals surviving in Mexico. Its population began to steadily increase in the early 1900s.
Northern elephant seals, like all marine mammals, are protected by the Marine Mammal Protection Act.
Though a complete population count of elephant seals is not possible because all age classes are not ashore at the same time, the most recent stock assessment reports with population estimates are available.
- Throughout Its Range
Northern elephant seal pups are black until they are weaned at about 6 weeks old, when they molt and turn light silver. Adults are dark brown or gray.
When males reach puberty at about 7 years old, they develop a large inflatable nose (proboscis). The proboscis overhangs their lower lip by about 8 inches. They also develop a robust, thick neck that is heavily creased and lighter in color than their dark bodies. Conversely, females maintain their smaller noses and smooth necks.
Fully grown males can reach lengths of over 13 feet and can weigh nearly 4,400 pounds. Females are significantly smaller than males, but are still grow to about 10 feet long and weigh up to 1,300 pounds.
Behavior and Diet
Northern elephant seals have a diet of mostly squid and fishes, but also rays and sharks.
Northern elephant seals spend much of the year—generally about 9 months—in the ocean. They are usually underwater, diving to depths of about 1,000 to 2,500 feet for 20 to 30 minute intervals with only short breaks at the surface. They are rarely seen out at sea for this reason. While on land, they prefer sandy beaches.
They fast during mating season and can lose up to 36 percent of their body weight during this time. When molting occurs, they shed their short, dense fur along with large patches of old skin. Molting takes from 4 to 5 weeks to complete.
Where They Live
Northern elephant seals are found in the eastern and central North Pacific Ocean. Though they range as far north as Alaska and as far south as Mexico, they typically breed in the Channel Islands of California or Baja California in Mexico. Northern elephant seals breed and give birth in California and Baja California, primarily on offshore islands, from December to March. Males feed near the eastern Aleutian Islands and in the Gulf of Alaska, and females feed further south in the offshore waters of Washington and Oregon. Adults return to land between March and August to molt, with males returning later than females. Adults return to their feeding areas again between the spring/summer molt and the winter breeding season.
Lifespan & Reproduction
Pups are born in early winter from December to January. Breeding occurs from December to March, and gestation lasts around 11 months. Northern elephant seals are polygamous—males establish dominance over large groups of females during the breeding season.
There is a notable difference in lifespan between males and females. Females generally live for about 19 years, while males only live for about 13 years.
These animals are polygynous breeders with a social hierarchy. Males form harems usually when they are 9 to 10 years of age, battling for status. Adult males use their large, inflatable noses during the winter breeding season to resonate sound when vocally threatening each other.
Females come ashore and within a few days give birth to a pup conceived in the previous breeding season. The pups are weaned after about a month. Just before her pup leaves, she breeds again and then returns to sea.
Entanglement in Fishing Gear
Northern elephant seals can become entangled in fishing gear, either swimming off with the gear attached or becoming anchored. Once entangled, seals may drag the gear for long distances, ultimately resulting in fatigue, compromised feeding ability, or severe injury, which may lead to reduced reproductive success and death.
Inadvertent vessel strikes can injure or kill seals. The projected increase in vessel traffic arising from the opening of trans-polar shipping routes (as arctic sea ice continues to decline) will increase the risk of vessel strikes and also increase ambient noise and pollution.
In the Spotlight
Northern elephant seals are protected throughout their range under the Marine Mammal Protection Act. NOAA Fisheries is working to protect this species in many ways, with the goal that populations remain stable and do not fall to depleted or threatened levels.
Minimizing Harassment and Illegal Feeding
As human interactions with seals and sea lions increase, so does the risk of disturbing or injuring these animals. For seals and sea lions that rest on our beaches, close encounters with people are harmful. Continued disturbances may cause mothers to abandon their pups. This species will haul out during molting season and may stay in the same area for weeks at a time. When they are molting they look like they are in very poor shape, but this is normal. Please do not attempt to approach these animals or interact with them in any way.
Reducing Interactions with Fishing Gear
Northern elephant seals can get entangled in fishing gear, causing injury and possibly death. NOAA Fisheries is working to better understand and characterize the frequency, geographic extent, and magnitude of these interactions. We are also working with researchers to identify and evaluate ways to safely and effectively reduce the potential for these interactions.
Overseeing Marine Mammal Health and Stranding Response
We work with volunteer networks in all coastal states to respond to marine mammal strandings. When stranded animals are found alive, NOAA Fisheries and its partners assess the animal’s health and try to return it to the water. When stranded animals are found dead—as is usually the case—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.
Marine Mammal Unusual Mortality Events
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.
Key Actions and Documents
NOAA Fisheries conducts various research activities on the biology, behavior, and ecology of the northern elephant seal. The results of this research are used to inform management decisions and ensure stable population levels for this species.
Determining the number of northern elephant seals in each population—and whether a stock is increasing or decreasing over time—helps resource managers assess the success of enacted conservation measures. Our scientists collect information and present these data in annual stock assessment reports.
Scientists in our Marine Mammal Laboratory conduct wide-ranging research on the biology, life history, and health of northern elephant seals including:
- Vital rates (survival and reproduction).
- Distribution and migration.
- Diet/foraging ecology.
- Threats such as disease, contaminants,and entanglement.