Anxiety Drugs Found in Rivers Make Salmon Take More Risks

In many streams and rivers, fish are swimming in a veritable soup of drugs. Components of that soup may be disrupting their behavior, according to a new study.

Atlantic salmon exposed to anti-anxiety medication during their migration were more successful in reaching their destination than drug-free fish, researchers reported Thursday in Science. That success may stem from increased boldness, the researchers found, a trait that could ultimately harm the fish in the long-run.

“On the face of it, it sounds like giving drugs to fish is beneficial,” said Jack Brand, a biologist at the Swedish University of Agricultural Sciences. “But any departure from natural behaviour is likely to have potential broad and negative consequences for the population.”