Young salmon exposed to anxiety medications swam past dams more quickly, raising questions about how pharmaceutical pollution may be altering fish behavior and survival in the wild.
Rebecca Dzombak reports for The New York Times.
In short:
- Scientists exposed juvenile salmon in Sweden to anxiety drugs and tracked their migration using tags; exposed fish navigated hydropower dams faster than others.
- The medications, present in many waterways due to pollution from waste and pharmaceuticals, appeared to make salmon take more risks and school less tightly when predators were nearby.
- Ecologists worry that these drug-induced behavioral changes could shift salmon survival patterns and disrupt food webs.
Key quote:
“It’s like playing poker. The more risks you take, the more chances you have to lose everything. In this case, the fish’s life.”
— Giovanni Polverino, behavioral ecologist at the University of Tuscia, Italy
Why this matters:
Pharmaceutical pollution is an emerging threat to aquatic ecosystems. Drugs like anti-anxiety medications, designed to alter brain chemistry, are now common in rivers and streams, where they can seep into the bodies of fish and other wildlife. These drugs may be reshaping fish behaviors critical for survival, like migration, schooling, and predator avoidance. Over time, such shifts could disrupt population dynamics, alter predator-prey relationships, and destabilize aquatic food webs. As freshwater systems become increasingly dosed with human pharmaceuticals, scientists warn we may be witnessing a form of unintended chemical engineering — one that could have ripple effects far beyond the fish.
