A Greenpeace activist holds up large cans of tuna on sale in a Korean supermarket in Koror. Greenpeace is campaigning for a global network of marine reserves covering 40% of the world's oceans and for a more sustainable fishing industry - two necessary steps to restoring our oceans to health. The group is also working with retailers and tuna brands across Europe, the Americas and the Asia-Pacific to increase the market share of sustainably sourced tuna.