According to a new report released by the International Union for Conservation of Nature 11 species of sharks around the world are at high-risks of extinction, while another five show a significant decline. The reason is, as usual, over-fishing, which is affecting shark species especially due to their low rates of reproduction. One of the most common practices among fishermen who capture sharks - and at the same time one of the main causes for the high mortality rate amongst sharks - is removing the fins and throwing the rest of the carcass back into the ocean.

"There's this idea that because these are widely ranging species, they're more resilient to fishing pressure. 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", said Sonja Fordham, deputy chair of the IUCN Shark Specialist Group (SSG) and policy director for the Shark Alliance conservation group.

In their study the SSG evaluated 21 species of sharks and other related species that regularly swim in areas of the ocean patrolled by fishing fleets. Out of the 11 species of sharks with high risks of extinction, the giant devilray was already classified as endangered.

The other five species of sharks showing population decline have not been listed yet, since the threat is not yet serious. Three of the species belonging to the thresher shark have never been assessed before and this is the first time they are found on the danger list. Nevertheless, the cause is clearly related to uncontrolled fishing, be it accidental or otherwise.

"They used to be taken as bycatch by boats targeting tuna and swordfish. 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", said Fordham.

The Regional Fisheries Management Organization is already taking action and has imposed a set of restrictions regarding shark finning, but so far the rules haven't been well defined allowing some fishermen to continue their activity without breaking the law in international waters.

"Fishery managers and regional, national and international officials have a real obligation to improve this situation. But it doesn't have to be like this. With sufficient public support and resulting political will, we can turn the tide", said Nicholas Dulvy from Simon Fraser University, leader of the report.