There's simply no limit to the sins people will commit for a tasty meal. The Japanese are notorious for their trade in bluefin tuna, while newlyweds in Bangkok, Shanghai and Singapore devour a gelatinous soup made from poached abalone and fins hacked from living sharks. But surely there's no need for you to feel bad about ordering sea bass in a London restaurant. Unless, of course, you consider that you may well be enjoying one of the very last members of the species. In ''Dead Seas'' we follow acclaimed journalist Taras Grescoe on a year-long, round-the-world trip, as he eats his way from the top to the bottom of the food chain with one purpose in mind: to find out whether he can continue to eat such delicacies in good conscience. As well as painting a vivid and often hilarious picture of the fascinating people Taras encounters, ''Dead Seas'' explores the impact we are having on sea life by overfishing and draws our attention to some of the ethical choices we can make. At a time when many of the fish we take for granted are on the verge of extinction, we need to face the fact that very soon jellyfish sandwiches may be all that is left for us to eat.