The world's oceans are in a dire state. Large predatory species are being decimated -- including sharks, whales, tuna, grouper, cod, halibut, swordfish and marlin -- and replaced by species with less commercial and nutritive value. In fact, a growing body of evidence suggests that the world's marine ecosystems have been altered so dramatically they are undergoing evolution in reverse, returning to a time when algae and jellyfish dominated the seas. The crisis is having an increasingly profound effect on humans. Fishing cultures from Newfoundland to West Africa are vanishing, and toxic algal blooms have closed beaches and recreational areas from Florida to the Black Sea. The damage is being caused by overfishing, climate change and destruction of habitat due to coastal development and pollution. Scientists and policy makers widely agree that a broad-based approach known as ecosystem-based management would help restore the oceans' productivity, but significant research and strong international cooperation are needed to bring about such a shift.

Colin Woodard has reported from more than 40 foreign countries on six continents and lived in Eastern Europe for more than four years. He is the author of Ocean's End: Travels Through Endangered Seas, a narrative, nonfiction account of the deterioration of the world's oceans. He also writes for The Christian Science Monitor and The Chronicle of Higher Education.