For nearly two decades, Edgardo Ochoa has picked away at a problem. A net here, some fishing line there — Conservation International’s marine and diving safety officer has single-handedly scooped up thousands of pounds of abandoned fishing gear from the bottom of the sea. It’s impressive, but it’s not nearly enough to make a dent: According to one estimate, nearly a third of fishing lines are lost or discarded at sea. This so-called “ghost gear” — along with lost nets and traps — is deadly for marine animals. Experts estimate that more than 300,000 whales and dolphins die each year after getting tangled in them. Once, Ochoa saw a whale caught in a fishing net that ended up severing its tail. With far more “ghost” nets than any one person can possibly handle, Ochoa created a course to teach recreational divers how to safely remove ghost gear from the sea. Over the past five years, that course has certified nearly 100 divers in Panama, Colombia, Mexico, Peru, Indonesia and Timor-Leste.…