A massive global study of sharks and rays shows more than a third are now threatened with extinction.
Colin Simpfendorfer, Professor of Marine Biology at James Cook University, was one of the authors of a paper released today in the journal Current Biology. He said the team of scientists looked at nearly 1200 species of sharks and rays and the closely related chimaeras.
"The first global assessment in 2014 concluded that just over 17 per cent of these species were threatened with extinction. The latest study raises this to over 32 per cent. This includes three species now listed as possibly extinct, representing perhaps the first global marine fish extinctions due to overfishing," said Professor Simpfendorfer.
He said the data available to scientists on sharks, rays and chimaeras was much greater now than in 2014, but it didn't make for better reading.
"In 2014 we reported on 1041 species and found that 181 were threatened. In the latest report we covered 1199 species, with 391 found to be threatened."
He said overfishing is the universal threat affecting all 391 threatened species and is the sole threat for just over 67 per cent of species.
"The extinction risk has increased over the past century with the growth of human populations and associated intensification of fishing and technological efficiency," said Professor Simpfendorfer.
He said fisheries, from small scale artisanal to large scale industrial, are the key threat.
"Almost all species of sharks and rays are taken unintentionally by fisheries. But while the catch may be incidental, sharks and rays are often kept for food and animal feed."
He said overfishing was interacting with other threats to produce the bulk of the remaining danger, primarily from coastal development (25.8%) and agriculture/aquaculture (9.5%), the effects of climate change (10.2%), and pollution (6.9%), with species disproportionately threatened in tropical and subtropical coastal waters.
"Science-based limits on fishing, effective marine protected areas, and approaches that reduce or eliminate fishing mortality are urgently needed. Immediate action is essential to prevent further extinctions," said Professor Simpfendorfer.
He said fisheries management measures - primarily catch limits - have succeeded in the rebuilding and sustainable exploitation of several species in the USA, Canada, Europe, Australia, and New Zealand.
"While Australia is currently doing a good job managing its sharks and rays, we can't take our eye off the ball. We know how quickly things can change for the worse, sometimes irreversibly," said Professor Simpfendorfer.
