Video Shows Rarely Seen Pacific Sleeper Shark Feeding 2,000ft Under the Sea

Japanese marine researchers have captured video footage of a rarely seen Pacific sleeper shark around 2,000 feet below the ocean surface.

The Somniosus pacificus is one of the largest deep-sea sharks in the world, reaching up to 14 feet in length. They are found across the North Pacific, from the surface down to depths of around 6,500 feet.

The footage was filmed by researchers from the Japan Agency for Marine-Earth Science and Technology, who were using baited camera systems to study deep-sea predatory and scavenging fish in Suruga Bay. Suruga is the deepest bay in Japan, with a maximum depth of around 8,200 feet.

For their research, which was conducted in 2016 and 2017 but has just been released in an academic journal, the Japanese scientists placed two baited cameras around 1,400 feet away from each other in the waters of the bay, at depths of roughly 2,000 feet.

According to their study—published in the Journal of the Marine Biological Association of the United Kingdom on May 18 this year—the cameras observed a single individual Pacific sleeper shark on July 21, 2016. The shark was a female, measuring around 10 feet in length.

In the footage, the shark can be seen slowly approaching the bait and trying to eat it.

The first arrival was recorded 43 minutes after the deployment of camera one. The researcher said the shark had "several remarkable features," including the snout being tangled in a broken fishing line and a parasitic crustacean attached to each eye.

The same shark was filmed by camera two, around 37 minutes after it had disappeared from the view of the first camera. Eventually, the shark returned to camera one around 31 minutes after leaving the view of camera two.

Using the data collected, the Japanese researchers calculated the average water speed of the Pacific sleeper shark to be about 0.34 meters per second.

The researchers say this is the first record of the swimming speed of Somniosus pacificus. The measurement is comparable to the speed of the related Greenland shark, or Somniosus microcephalus, which has the slowest comparative swimming speed—when adjusted for size—of any fish.

The researchers have estimated that there are approximately 1,150 sleeper sharks living in the bay at depths of between 500 meters (1,640 feet) and 1,000 meters (3,280 feet.)

The scientists added that it was rare to capture footage of Pacific sleeper sharks active in deep waters.

Pacific sleeper sharks appear to feed mostly on the sea floor, with their diet including invertebrates and fish, as well as marine mammals such as some seal and dolphin species. Because of their slow swimming speed, the sharks rely mainly on scavenging for food and hunt only rarely.

A Pacific sleeper shark
Video footage of a Pacific sleeper shark captured in Japan's Suruga Bay. JAMSTEC