Fish are under a lot of pressure. Overfishing is one big threat, with most of the world’s fish stocks being used unsustainably. Climate change is another problem, as is plastic pollution. Then, there are the natural problems they have to face, like predation and parasites. All of these are stressors for fish, and the situation is getting worse. But how do you know how bad it’s getting, when we’ve only been studying some things for the past couple of decades? Natalie Mastick, currently a postdoctoral researcher at the Peabody Museum of Natural History at Yale University, thought long and hard a…