Video: Group of Sea Lions Chases After Boat, Make ‘Zombie’ Sounds

A sea lion is pictured on the beach in Sandfly Bay near Dunedin, New Zealand, on Sept. 21, 2011. (Martin Bureau/AFP/Getty Images)

Researchers in Alaska captured the moment a raft of sea lions pursued their boat.

According to Yahoo News, the researchers were on a marine bird survey near Alaska’s Katmai National Park and Preserve when they spotted the sea mammals.

The sea lions could be heard making unusual noises, which some have described as “zombie-like.”

The National Park Service released a video of the raft along with the survey details.

“In addition to tallying animals, these studies help identify critical coastal areas in the parks,” the service wrote. “They highlight where birds congregate and which species are likely to be found there. Armed with such specifics, park management is better equipped to develop policies protecting sensitive areas when faced with human impacts to the coast, such as oil spills, development, and changing shipping lanes.”

They also spotted wolves along the coast.

“Experiences like these reveal the character and intelligence of these amazing marine mammals,” the service wrote. “Sadly, their western populations are endangered. Surveys such as this help wildlife management agencies understand their needs and better protect them.”

The sea lions near Alaska (National Park Service)

The sea lions are seen swimming after the research boat (National Park Service)

They're also seen pursuing the vessel (National Park Service)

According to NOAA, sea lions and seals are both pinnipeds, but they have marked differences.

“But seals’ furry, generally stubby front feet — thinly webbed flippers, actually, with a claw on each small toe — seem petite in comparison to the mostly skin-covered, elongated fore flippers that sea lions possess,” the agency says.

“Secondly, sea lions have small flaps for outer ears. The ‘earless’ or ’true’ seals lack external ears altogether. You have to get very close to see the tiny holes on the sides of a seal’s sleek head.”

It adds: “Third, sea lions are noisy. Seals are quieter, vocalizing via soft grunts.”

Meanwhile, “While both species spend time both in and out of the water, seals are better adapted to live in the water than on land. Though their bodies can appear chubby, seals are generally smaller and more aquadynamic than sea lions. At the same time, their hind flippers angle backward and don’t rotate. This makes them fast in the water but basic belly crawlers on terra firma,” researchers say.

(Martin BernettiAFP/Getty Images)

The Marine Mammal Center says that sea lions can get to 850 pounds for males, and females can weigh 220 pounds.

California sea lions are located from Vancouver Island, British Columbia to the bottom of Baja California in Mexico, the Center says.

“They breed mainly on offshore islands, ranging from southern California’s Channel Islands south to Mexico, although a few pups have been born on Año Nuevo and the Farallon Islands in central California. There is a distinct population of California sea lions at the Galapagos Islands. A third population in the Sea of Japan became extinct, probably during World War II,” it says.