[00:00.01]Tuna are predators.[00:02.01]They herd smaller fish to the surface, where they can be picked off one by one.[00:06.20]They are high-speed fish - the cheetahs of the ocean.[00:09.65]They're also the wildebeest[00:11.55]They herd together in their thousands[00:13.84]And undertake epic migrations across the Pacific in search of their prey.[00:18.11]If these animals lived on land[00:20.28]They'd be famous for providing the greatest wildlife spectacle on Earth.[00:24.73]Instead, they're better known as a filling for a sandwich.[00:28.69]In an ocean with no marine reserves, migratory fish have nowhere to hide.[00:33.76]Up to two kilometres long and 200 metres deep[00:38.23]"purse seine" nets are designed to encircle schools of tuna.[00:42.55]A fisherman checks his nets[00:44.57]Breathing air pumped down a tube from the vessel above.[00:47.86]It's not only tuna that get caught in these nets.[00:51.10]A lone turtle was in the wrong place at the wrong time.[00:54.76]She can only hold her breath for a few minutes[00:57.56]And the path to the surface isn't clear.[01:00.35]She begins to panic.