By Richard Black: Environment correspondent, BBC News
Many countries whose fishing fleets catch large numbers of sharks have failed to meet a 10-year-old pledge on conserving the species, a report says.
The wildlife trade monitoring network Traffic and the Pew Environment Group say most of the main shark fishing nations do not manage fisheries well.
Ten years ago, governments agreed a global plan to conserve sharks.
An estimated 100 million sharks are killed each year, with nearly a third of species at risk of extinction.
"Where shark populations are healthy, marine life beneath the waves thrives” states Jill Hepp of the Pew Environment Group.
Many fisheries target the fins for use in shark fin soup; and a number of countries, inclduing the US, have recently passed measures aimed at regulating the trade.
Neither of the two countries catching the most sharks - Indonesia and India - has yet finalised national plans of action for protecting sharks.
This was one of the main recommendations of the 2001 agreement under the UN Food and Agriculture Organization (FAO) that sharks needed international management.
Of the top 20 shark-catching nations, which collectively account for 80% of the global catch, only 13 have national plans in place.
"The fate of the world's sharks is in the hands of the top 20 shark catchers, most of which have failed to demonstrate what, if anything, they are doing to save these imperiled species," said Glenn Sant, leader of Traffic's global marine programme.
"They need to take action to stop the decline in shark populations, and help ensure that the list of species threatened by overfishing does not continue to grow."
Sharks are particularly vulnerable to overfishing because they live long lives and reproduce slowly.
As well as intentional fishing, many are caught accidentally in large nets and on the hooks of longline boats targeting species such as tuna and marlin.
Traffic and Pew are asking the FAO to review implementation of the 10-year-old agreement when it meets later this year.
The 10 recommendations to governments agreed back in 2001 include identifying and protecting key habitat, ensuring catches are sustainable, and minimising waste and discards.
Many sharks are top predators; and there is an abundance of biological evidence to show their removal can have major impacts on the rest of the ecosystem.
"Where shark populations are healthy, marine life beneath the waves thrives; but where they have been overfished we see that world fall out of balance," said Jill Hepp, Pew's global shark conservation manager.
"Shark-catching countries and entities must stand by their commitments and act now to conserve and protect these animals."
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