Specialists with IUCN -- International Union for the Conservation of Nature and Natural Resources -- of the World Conservation Union found said more than half of world's population of sharks are at risk, the BBC reported. Sharks are affected by accidental and targeted fishing because they reproduce slowly.

To counter the threat, the scientists from Gland, Switzerland, are calling for global catch limits, an end to the practice of removing fins, and measures to reduce the risk of incidental catches.

"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 and policy director for the Shark Alliance conservation group.

The SSG reviewed data on 21 species of sharks and their cousins, the rays, that swim in upper portions of the open ocean where they are exposed to fishing fleets.

Of the 21, one -- the giant devil ray -- was classified as endangered, 10 species were listed as vulnerable and five were listed as near threatened.