Northern elephant seal. Photo: NOAA Fisheries
Northern elephant seal. Photo: NOAA Fisheries
About the Species
The northern elephant seal is the largest of the “true” seals 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. A small population survived in Mexico and the population began to steadily increase in the early 1900s. Today, robust populations of northern elephant seals in the U.S. and Mexico are derived from those few hundred individuals that survived in Mexico.
Northern elephant seals, like all marine mammals, are protected by the Marine Mammal Protection Act.
Population Status
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.
Protected Status
Appearance
Northern elephant seal pups are black until they are weaned at about 6 weeks old, and 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, or "proboscis." The proboscis overhangs their lower lip by about 8 inches. They also develop a robust, thick neck with calloused skin that appears pink and light grey and creates a shield to protect them from harm when fighting other males.. 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 also quite large, growing to about 10 feet long and weighing up to 1,300 pounds.
Behavior and Diet
Northern elephant seals’ diet primarily consists of squid and fishes, but they also consume rays and sharks.
Northern elephant seals spend about 9 months of the year in the ocean. Most of this time is 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.
Northern elephant seals fast during the 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 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, they typically breed and give birth in the Channel Islands off California or Baja California in Mexico, primarily on offshore islands from December to March. Males feed near the eastern Aleutian Islands and in the Gulf of Alaska, and females feed farther 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.
Northern Elephant Seal Range
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 polygynous breeders with a social hierarchy. Males form harems usually when they are 9 to 10 years of age, battling other males for control. Adult males use their large, inflatable noses during the winter breeding season to resonate sound when vocally threatening each other.
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.
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, and just before she leaves her pup, she breeds again and then returns to sea.
Threats
Entanglement in Fishing Gear
Northern elephant seals can become entangled in fishing gear, either swimming off with the gear attached or becoming anchored and possibly drown if they cannot reach the surface to breathe. Once entangled, seals 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, lower survival rates and/or death.
Vessel Strikes
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.
Scientific Classification
| Animalia |
Chordata |
Mammalia |
Carnivora |
Phocidae |
Mirounga |
angustirostris |
