Editor’s note: Throughout the world’s oceans, a silent plague is snaring marine life and smothering seafloors. Ghost nets — commercial fishing nets that are left behind or lost — can drift for thousands of miles, injuring or killing fish or whales that get tangled in them. Now, a small army is being recruited to help remove them wherever they’re found. One of the main figures behind this effort, Conservation International Marine Safety Officer Edgardo Ochoa, explains. Working on the ocean is often a source of great enjoyment: You get to see extraordinary things such as coral reefs and exotic species and revel in the vastness of the open sea. But, sometimes it can be a source of emotional turmoil. Last month, as I was teaching local community members and Conservation International staff about removing ghost nets at a workshop in Nuquí, Colombia, we had a shocking and up-close glimpse of the problem: Several locals came to me and said they had spotted a humpback whale nearby with its tail caught in a net.…