Ocean plastic makes baby fish ignore their predators

Oona Lönnstedt

Ocean plastic makes baby fish ignore their predators

It’s a tough world for baby fish: They’re easy pickings for many predators, and many don’t manage to make it to adulthood. Humans might be making it even tougher: Each year we dump more than 4 million metric tons of plastic into the ocean, where it breaks down into pieces small enough to get snapped up by these centimeter-long swimmers. To see how this pollution might be affecting young fish, researchers raised European perch (Perca fluviatilis) in water filled with polystyrene plastic particles, in amounts matching the average and highest concentrations found along the Swedish coast. Only 81% of the perch in plastic-filled water hatched compared with 96% in clean water, according to a paper published online today in Science. Even the ones that managed to hatch grew more slowly and had bellies full of the plastic particles (the tiny spheres along the underside of the fish above) after 2 weeks—and those exposed to the highest amount of plastics completely ignored the smell of injured perch added to their tanks, a scent that usually makes them freeze to avoid being seen. When put in a tank with pike predators, these polystyrene-munching perch were killed off three times more quickly than those raised in plastic-free water. The authors say these dramatic effects may be contributing to perch population declines in the Baltic Sea, and could cut short the lives of fish worldwide.

*Update, 5 December, 4:55 p.m.: This study is now the subject of an ongoing investigation, and Science has published an "Editorial expression of concern" about the paper.