Canned tuna, a "magical wonder fish," is sooooo cheap. Just ignore that "shadowy multinational corporation" behind the curtain, and the bloodlust of Chicken of the Sea's creepy mermaid mascot:
The "dirty little secret" that Greenpeace unveils in the video is the problem of innocent bystanders … uh, byswimmers. Basically, tuna fleets use fish aggregating devices to attract tons of tuna. But the devices also attract other fish, which get caught and sacrificed to the bottom line.