May 22, 2008
Study Finds Sharks at Risk of Extinction
An international study by specialists with the IUCN Shark Specialist Group (SSG) has found that more than half of the world's sharks are at risk of extinction.
The report, the first to determine the global threat status of oceanic pelagic sharks and rays, found that 16 out of 21 species are at increased risk of extinction.
The threat is primarily caused by targeted fishing for valuable meat and fins, along with indirect take in other fisheries that are typically unregulated and unsustainable. Sharks and rays are particularly vulnerable to overfishing because they reproduce slowly.
The study also found that increasing demand for the delicacy "Ëshark fin soup', driven by fast-growing Asian economies, often results in shark fins being retained while the carcasses are discarded. Frequently, such discarded rays and sharks are not even recorded.
The IUCN (formerly the World Conservation Union) specialists placed 11 species on the high-risk list, and said five more are showing signs of decline. They are calling for global catch limits, an end to the practice of removing fins, and measures to reduce incidental catches (bycatch).
"There's this idea that because these are widely ranging species, they're more resilient to fishing pressure," Sonja Fordham, deputy chair of the IUCN Shark Specialist Group (SSG) and policy director for the Shark Alliance conservation group, told BBC News.
"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."
"Fishery managers and regional, national and international officials have the opportunity and the obligation to halt and reverse the rate of loss of biodiversity and ensure sharks and rays are exploited sustainably," said lead author Nicholas Dulvy from the Center for Environment, Fishers and Aquaculture Science in the UK.
"The current rate of biodiversity loss is ten to a hundred times greater than historic extinction rates, and as humans make increasing use of ocean resources it is possible that many more aquatic species, particularly sharks, are coming under threat."
"This does not have to be an inevitability. With sufficient public support and resulting political will, we can turn the tide," he said.
The study recommends governments take the following steps to protect the sharks and rays:
- Establish and enforce science-based catch limits for sharks and rays
- Ensure an end to shark finning (removing fins and discarding bodies at sea)
- Improve the monitoring of fisheries taking sharks and rays
- Invest in shark and ray research and population assessment
- Minimize incidental catch ("Ëbycatch') of sharks and rays
- Cooperate with other countries to conserve shared populations.
"The traditional view of oceanic sharks and rays as fast and powerful too often leads to a misperception that they are resilient to fishing pressure," said Fordham, who co-authored the study's report.
"Despite mounting evidence of decline and increasing threats to these species, there are no international catch limits for oceanic sharks. Our research shows that action is urgently needed on a global level if these fisheries are to be sustainable," she said.
The SSG reviewed data on the 21 species of sharks and rays that inhabit the upper portions of the open ocean, where they often become exposed to fishing fleets.
Of the 21 species, the giant devilray was the only one found to be Endangered, but 10 were considered Vulnerable. A further five were found to be Near Threatened, meaning evidence of decline is not serious enough to warrant a full listing.
The classifications are based on a range of factors that examine past declines in population size. For instance, a population decreasing by 50% in 10 years would typically qualify as Endangered.
Some of these species have been examined before, but for others the listing is new.
The main threat to sharks is accidental and targeted fishing, the study found.
"They used to be taken as bycatch by boats targeting tuna and swordfish," said 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."
Several bodies that regulate fisheries in international waters, including the Regional Fisheries Management Organizations (RFMOs), have established measures to reduce shark finning, but with different standards in place fisherman are able to side step the regulations.
Conservation groups say exploding East Asian economies are driving the market for fins.
"Fishery managers and regional, national and international officials have a real obligation to improve this situation," Nicholas Dulvy from Simon Fraser University in Vancouver, the report's lead author, told BBC News.
"But it doesn't have to be like this. With sufficient public support and resulting political will, we can turn the tide."
The updated risk assessments will be part of the IUCN's Red List of Threatened Species, which will published later this year.
The study's report was released at the Convention on Biological Diversity (CBD) meeting in Bonn, and is published in the latest edition of the journal Aquatic Conservation: Marine and Freshwater Ecosystems.
On the Net:
IUCN Shark Specialist Group
Aquatic Conservation: Marine and Freshwater Ecosystems