Researchers from The University of Western Australia have captured rare vision of a sleeper shark during an expedition exploring the biodiversity of the Tonga Trench in the south-western Pacific Ocean.
Research Fellow Dr Jessica Kolbusz, from the Minderoo-UWA Deep-Sea Research Centre, said the sleeper shark was filmed on the eastern side of the Tonga Trench at a depth of 1,400 metres in 2.5C waters.
"Pacific sleeper sharks have rarely been observed in the Southern Hemisphere," Dr Kolbusz said.
"They are frequently caught as bycatch in the Northern Hemisphere however they have seldom been studied."
The slow-moving sharks can grow up to seven metres in length and the individual captured on film is estimated to be about 3.5 metres.
"We don't know how long they live for, but there is a current study under way by the Alaska Fisheries Science Center using radiocarbon dating to find their plausible age range — it likely has a growth rate that is comparable to the Greenland shark," Dr Kolbusz said.
The unique vision captured shows rows of teeth when the shark opens its mouth to feed on the bait, but the range of teeth the species can possess is unknown due to a lack of research.
"They are opportunistic predators and scavengers that eat slow-moving bottom feeders and carcasses, and stomach contents have suggested the capability of small dashes to catch fast-swimming fish," Dr Kolbusz said.
The expedition aimed to answer questions around how biodiversity and species abundance changed between 1,000 metres to 10,000 metres and researchers were examining whether they are driven by pressure or habitat.
"The Tonga Trench is also long the path of Antarctic Bottom Water that moves into the equatorial and north Pacific Ocean forming a key pathway for global ocean circulation," Dr Kolbusz said.
"On this expedition, at these depths, we observed a few unique species including a Richardson's ray, cut-throat eels, whiplash squids and blue hakes."
This research was conducted in collaboration with Inkfish and Kelpie Geoscience.
