One in seven deepwater sharks and rays are at risk of extinction due to overfishing, a study says.
The research has prompted calls for urgent action to police the international liver oil trade and protect the species that live in the ocean depths, including Australian waters.
Experts are also demanding fishing regulations for deepwater sharks and rays, which they claim are some of the species most vulnerable to overfishing.
James Cook University marine biology professor Colin Simpfendorfer is among the international team of scientists involved in the study.
He said deepwater sharks could be found in all Australian waters below 200m.
Professor Simpfendorfer said they needed protection, along with rays, around the world like similar marine mammals.
"We have many species of sharks and rays in our deep waters," he said.
"Deepwater sharks and rays have biological characteristics similar to marine mammals which were formerly exploited for their oils and are now highly protected."
For the study, the international team analysed data on 521 deepwater shark and ray species to model populations.
They then used the International Union for Conservation of Nature (IUCN) list of threatened species categories and criteria to estimate the global extinction risk.
The study found overfishing, coupled with the slow development and reproduction of many deepwater shark and ray species, make them more susceptible to population decline.
IUCN Species Survival Commission deputy chair Rima Jabado said the study highlighted the need to police the international liver oil trade.
"Deepwater sharks and rays have been out of sight, out of mind for too long," she said.
"Now is the time to take action to prevent further endangerment."
Some species take decades to mature, says biologist Nicholas Dulvy from Simon Fraser University in Canada.
In the case of the Greenland shark it can take up to 150 years to reach adulthood.
"Some only produce 12 pups throughout their entire life," he said.
"Because of their relatively large size and widespread distribution deepwater sharks and rays play a vital ecological role, concentrating and dispersing nutrients throughout deep ocean habitats."
The study has been published in the journal Science.
