The Glide Bracelet

Elephant seals are tracked with electronic instruments for a variety of reasons, including where they travel and feed during their foraging migrations, how they expertly navigate through the ocean, how much they are able to eat during foraging trips, how they avoid predators like white sharks and killer whales, and even how they sleep. 

The elephant seal tracks researchers have shared with Fahlo are also helping scientists learn how these behavioral strategies are different between male and female seals, and how they develop as seals grow older. In recent years, elephant seals have helped scientists understand more about the ocean environment by carrying tags that collect information about chlorophyll content, dissolved oxygen, light levels, and the distribution of small fish and squid in the twilight zone (200–1000 meters deep) of the ocean. All of these metrics of ocean health provide valuable insight into the distribution and abundance of important resources that large predators like elephant seals rely on.

Elephant seals are tracked in a couple different ways. First, a select few seals each year are equipped with flipper tags with a unique alphanumeric ID that allows researchers to find them on the beach each year and record their age, whether they are raising a pup, and which other seals they are interacting with. 

Seals are also often given a hair dye mark on their fur to help researchers more easily identify individual seals in a large group. To track where seals go and measure other variables in the ocean, scientists carefully sedate and equip seals with location trackers that either transmit data in real time to a satellite when the seal is at the surface, or store the data onboard the device for scientists to recover from the seal when it returns to the beach to breed or molt in between foraging migrations. The trackers are affixed to the seal’s fur with a quick-setting marine glue. After the tags are recovered, the seals naturally shed the remaining glue through a process called a catastrophic molt, during which they shed all their fur and outer layer of skin at once.

Nope! Because seals are so large, they can carry these small instruments with no adverse effects. Scientists partner with a federal permitting agency and institutional care committee to ensure they are using best practices, including selecting tags that are small and light. They also undergo extensive animal handling training which includes monitoring during and after sedation. Together, these steps ensure that trackers do not impact the seals.

Seals are not considered critically endangered, although there are a number of threats they face in the wild, including hunting, marine debris (including microplastics), entanglement, and boat collisions.

Elephant seals in particular were nearly hunted to extinction for their oil in the 1800s; today their numbers have rebounded thanks to legal protections and the help of those like our partners at the Beltran Lab at UCSC.

Seals typically live along the coast in colder waters (thank you, blubber!), but most call the Arctic and Antarctic home. The northern elephant seals we track reside at the Año Nuevo State Reserve in California, though you can spot this species anywhere in the eastern and central North Pacific Ocean, sometimes as far north as Alaska!

It depends on the species and sex—females generally live longer than males. The average lifespan for harbor seals in the wild is around 15 years; gray seals can live 25–30 years; elephant seals 14–20+ years; harp seals around 30 years.

Depending on the species, seals can hold their breath underwater for anywhere from 15 minutes to 2 hours! The bigger the seal, the larger the lung capacity; male elephant seals can reach the 2 hour mark without surfacing for air. They can also dive deeper than any other seal species—up to 5, 577 ft (1700 m) in search of food.

There are two types of seals: true seals, which are earless (like the elephant seal) and flop around on land on their bellies, and eared seals (like sea lions) whose rear flippers help them “walk.” All seals, sea lions, and walruses are pinnipeds—marine mammals with front and rear flippers who live both in water and on land.

Adult male elephant seals sport an extra-long nose that looks similar to an elephant's trunk! Instead of a trumpet, it produces a loud roaring noise used during mating season to establish dominance among competing bulls. Southern elephant seals are also the largest seal species with males growing up to 20 ft long (6 m) and weighing in at an impressive 8,800 lb (3,991 kg).