A recent deep-sea expedition by the National Geographic Pristine Seas team has cast a spotlight on the previously under-explored biodiversity of Papua New Guinea’s vast ocean depths, uncovering potentially new species records and making the first reported sighting of a massive sleeper shark in the region.

The expedition, led by marine researcher Aaron B. Judah, utilised baited deep-sea cameras in the areas of Mussau and Lovongai to survey predator and scavenger communities, covering depths ranging from 426 meters down to 2,391 meters.

One of the most exciting discoveries occurred near Tingwon Island, where cameras deployed at over 2,300 meters captured footage of an enormous female sleeper shark.

“While the bottom was sandy and barren, we were surprised and excited to find an enormous female sleeper shark,” Judah reported. “This is the first time this group of sleeper sharks has been reported in Papua New Guinea.”

While the exact species remains unidentified, researchers believe it could be the Pacific or Southern sleeper shark, both known to reach lengths exceeding six meters. This sighting follows recent new records of sleeper sharks in Palau and the Solomon Islands in 2024.

The team has documented a rich diversity of deepwater life, including swarms of shrimp, curious nautilus, deepwater red snappers, and sixgill sharks. Crucially, their observations include:

• New National Records: Possible first live observations of multiple species in PNG, as well as the first recorded sightings of deepwater skates and “slick head” fishes (named for their lack of scales on their heads).
• Endemic Sharks: Near Tsoilik, at a depth of 426 meters, the team possibly observed Steven’s swell shark, a species endemic to Papua New Guinea. This underlines the unique biodiversity heritage of the country, as this shark has been recorded nowhere else globally.

Researchers noted that the discovery of species with restricted ranges, like the swell shark, highlights the critical importance of conservation management for PNG’s deep-sea environment.

“The deep sea [was] teeming with interesting and sometimes unexpected life that is highly adapted for the extreme environment,” Judah concluded. The team is expected to continue sharing its findings as it processes the wealth of data collected from the planet’s largest, and often least-understood, ecosystem.