'Conservationists say a key wildlife summit could be the "last chance saloon" for saving sharks and rays pushed to extinction by the shark fin trade.
About 100 million sharks are estimated to be killed each year for their fins and meat.
On Sunday, countries will discuss giving more species of sharks and rays protection under wildlife trade rules.
These include mako sharks and the little-known "rhino rays".
Wedgefish and guitarfish are collectively known as "rhino rays", because of their elongated snouts. They are now the most endangered marine fish group, according to a recent scientific assessment.
"With this new science just come out, fresh in everyone's minds a month ago, on these wedgefish and guitarfish, it's clearly last chance saloon for them," Luke Warwick of the Wildlife Conservation Society told BBC News.
The fins of wedgefish and guitarfish can be worth as much as a thousand dollars a kilogramme, he said, making them one of the most highly-valued species in the shark fin trade.'
Read More:Extinction: Last chance to save 'rhinos of the oceans'