Atlantic bluefin tuna are surrounded by fishing nets during the opening of the season for tuna fishing off the coast of Barbate, Cadiz. (Emilio Morenatti/AP)

The video, which includes footage taken aboard a purse-seine vessel last year, shows the impact of using Fish Aggregating Devices (FADs) . (Warning: the video is a bit gory.) This floating gear attract a range of species, not just tuna, to the surface. As a result, the vessels end up hauling in and killing manta rays, whale sharks and other species.

In less than a month the Western and Central Pacific Fisheries Commission will meet and discuss what conservation measures it should take for a range of marine species.

“Consumers have the right to know what is destroyed and discarded in order to fill their cans with tuna,” said Sari Tolvanen, a Greenpeace International oceans campaigner. “This shocking video is a wake-up call: we as consumers, can demand that retailers give shelf-space only to responsibly-caught tuna. Without significant changes to global fishing practices and more protected marine reserves across the world’s seas, we will literally fish away future tuna supplies, jobs and healthy oceans.”

At the same time, several environmental groups are lobbying delegates at the annual International Commission for the Conservation of Atlantic Tunas (ICCAT) meeting to take stronger measures to prevent the accidental capture of sharks.The Pew Environment Group released a report Tuesday showing sharks taken as bycatch could account for as much as half of all shark landings.

“Banning wire leaders and not allowing vessels to retain certain species would help reduce the vast number of sharks caught and killed in Atlantic fisheries,” said Jill Hepp, manager of global shark conservation for the Pew Environment Group.

Whether global policymakers take the environmentalists’ advice, however, remains to be seen. Still, shark advocates will be celebrating Wednesday, because the Florida Fish and Wildlife Conservation Commission passed a measure to ban the harvest of tiger sharks and scalloped, smooth and great hammerhead sharks in state waters.

Warning. The following video is graphic.