“It’s certainly possible [that the lost shark survives]’,” Professor Simpfendorfer said. “We can’t rule it out.”
Sharks and rays in broadscale decline in many parts of the world, with overfishing “the major problem that’s driving them towards extinction”, he said, adding that half the species in the Arabian Sea are threatened. In Australian waters, gulper sharks and the whitefin swellshark are among those at risk.
James Watson, a professor at the University of Queensland, said many threatened species were “in the hospital on the way to the morgue”.
Professor Watson this week was an author of a Nature Communications paper that found just 40 per cent of the world’s forests were considered to be of high so-called landscape-level integrity, with just 27 per cent of that located in nationally protected areas.
“Forests hold half the world’s species,” he said, adding that 60 per cent “are in serious decline”.
Most of the best remaining forests are located in Canada, Russia, the Amazon and Papua New Guinea, but these face severe threats from logging and other pressures, he said.
Globally, amphibians such frogs are more at risk than bird species, with 14 per cent threatened, and mammals at 26 per cent, the IUCN said.
“Many amphibians have very restricted ranges to begin with and, to top it off, they are being pummeled by an onslaught of threats,” Kelsey Neam, IUCN’s Programme Officer for the animal group, said.
“The top three threats to amphibians worldwide are human-caused: expanding agriculture for crops and livestock grazing, logging of forests, and the expansion and ecological footprint of towns and cities,” she said.
One threat is the spread of chytridiomycosis, a deadly disease caused by a fungus that affects their ability to breathe through their skin or absorb nutrients. Climate change, particularly extreme droughts, are another stressor and may be operating with disease to exacerbate population declines,” Ms Neam said.
Some 80 of the 96 harlequin toad species, for instance, are listed as endangered, critically endangered, or even extinct like the Chiriqui harlequin toad (Atelopus chiriquiensis), according to the latest Red List.
Still, some amphibians can make a comeback. Researchers in Costa Rica rediscovered the American Cinchona plantation treefrog in 2007 and it now survives in several protected areas in Costa Rica and Panama.
“It goes to show that if we invest in conservation by protecting critical habitats, we can help these species have a fighting chance at long-term survival,” Ms Neam said.
Peter Hannam writes on environment issues for The Sydney Morning Herald and The Age.