More than half of the world’s ocean-going sharks are at risk of extinction, that is what a new analysis concludes.
Specialists with IUCN (formerly the World Conservation Union) found that 11 species are on the high-risk list, with five more showing signs of decline.
As they reproduce slowly, sharks are particularly affected by over-fishing.
The scientists are calling for an end to the practice of removing fins, global catch limits, and measures to minimise incidental catches (bycatch).
“There’s this idea that because these are widely ranging species, they’re more resilient to fishing pressure” said Sonja Fordham, deputy chair of the IUCN Shark Specialist Group (SSG), and policy director for the Shark Alliance conservation group.
“In fact they’re becoming species of serious concern because there are no international catch limits for sharks. There are intense fisheries on the oceans, and they remain pretty much unprotected.”
Data have been assessed by the SSG on the 21 species of sharks and their close cousins the rays, expose to fishing fleets because they swim in upper portion of the open ocean.
Endangered, Vulnerable or Near Threatened
Of the 21, one is assessed as Endangered, the giant devilray, and 10 are Vulnerable. Five others are listed as Near Threatened, which means that the signs of decline are not serious enough yet to merit a full listing.
Based on a range of criteria, the classifications look at past or forecast declines in population size. As an example, a population shrinking by 50% in 10 years would usually qualify as Endangered.
Some of these species have been assessed before, but others, including the three species of thresher sharks with their spectacularly long tails, the dangerlisting is new.
Accidental and targeted fishing remains the main threat to sharks.
“They used to be taken as bycatch by boats targeting tuna and swordfish” said Sonja Fordham. “But now as those species are declining we’re seeing more fishermen targeting sharks.”
“Porbeagle and shortfin mako are targeted for fins and meat; species like blue shark are likely to be finned, but particularly in Europe we’re seeing more blue shark being landed.”
‘Obligation to improve this situation’
In order to curb shark finning, several of the bodies that regulate fisheries in international waters, the Regional Fisheries Management Organisations (RFMOs), have set up measures. But there are different standars in place, which enables fishermen to work around the regulations.
Conservation groups say the market for fins is increasing, as East Asian economies boom.
“Fishery managers and regional, national and international officials have a real obligation to improve this situation” commented the report’s lead author, Nicholas Dulvy, from Simon Fraser University in Vancouver.
“But it doesn’t have to be like this. With sufficient public support and resulting political will, we can turn the tide.”
Released at the Convention on Biological Diversity (CBD) meeting in Bonn, the report will be published in the journal Aquatic Conservation : Marine and Freshwater Ecosystems.
When it’s published, later this year, the new risk assessments will be included in the IUCN List of Threatened Species.