This photo of a freshly cut dorsal fin from a scalloped hammerhead shark (Sphyrna lewini), was taken in 2006 on a long-lined fishing boat in Cocos Island, 300 miles off the Pacific coast of Costa Rica. Cocos was declared a UNESCO World Heritage site and is the home to one of the world's richest shark populations. It has also become a major target for long-lined shark fishing.
Every year, humans kill an estimated 100 million sharks. The threats we pose are many. By-catch: the accidental killing of sharks in fishing gear intended for other species. Illegal poaching and hunting: selling shark fins for soup and sportfishing for shark-jaw trophies. Nets: placed along coastlines to keep sharks away from beaches. Removing sharks in large numbers can have ripple effects that throw entire ecosystems out of balance.