In case you thought the only ones popping anxiety meds were stressed-out office workers and cable news junkies—think again. Turns out, the fish in our rivers are swimming in a cocktail of pharmaceuticals, and it’s starting to mess with their heads. Literally.
A new study out of Sweden found that Atlantic salmon exposed to anti-anxiety medication during their annual migration were actually more successful in making it to the sea. That’s right—medicated salmon were blazing past obstacles like hydroelectric dams faster than their drug-free counterparts. Sounds great, right? Except there’s a catch.
Chill Salmon = Risky Salmon
The drug in question is clobazam—a benzodiazepine used to treat anxiety in humans. Researchers implanted it into juvenile salmon right before they began their trek from Sweden’s River Dal to the Baltic Sea. The goal? To figure out what happens when wild fish end up with the same chemicals humans flush down the toilet.
The results were… weird. The clobazam-boosted salmon were faster, more decisive, and way bolder than the sober fish. They crossed dams two to three times faster, saving nearly five hours on their journey. That might not sound like much, but when you’re dodging spinning turbine blades the size of a truck, speed counts.
“They’re probably not overthinking it,” said Olivia Simmons, a salmon biologist who wasn’t part of the study. “While the other fish are cautiously weighing their options, the drugged-up salmon are like, ‘Screw it, I’m going in.’”
So What’s the Problem?
At first glance, drugged salmon crushing migration sounds like a win. But biologists are pumping the brakes. Jack Brand, the lead researcher from the Swedish University of Agricultural Sciences, says these bolder behaviors might not be so great in the long run.
“We suspect the clobazam makes them more solitary and risk-prone,” he explained. That might help them navigate a dam, but once they hit open water, those loner instincts could get them killed. Fish that don’t stick with the group—also known as a school—are way easier targets for predators. Think of it as the fish version of wandering off in bear country.
Oh, and by the way, clobazam wasn’t the only drug in play. Some of the test salmon were also dosed with tramadol, a painkiller. In people, mixing these two drugs is usually a bad idea, but in fish, tramadol didn’t seem to do much—good or bad. Still, that’s not exactly comforting.
A Bigger, Weirder Problem
If you’re wondering how these drugs are getting into rivers in the first place, it’s not that complicated. Humans take them, flush them, or toss them—then wastewater treatment plants mostly fail to filter them out. The result? A steady trickle of everything from antidepressants to chemo drugs floating into lakes and rivers.
Scientists have found over 900 pharmaceutical ingredients in waterways around the world. Let that sink in. And many of these meds act on brain chemistry that humans share with fish and other animals. In other words, what calms down your Aunt Linda might be turning a trout into a daredevil.
“This is a global concern,” said ecotoxicologist Karen Kidd. “We have no idea what the full mix of these chemicals is doing to aquatic life. And we’re not just talking fish—this affects everything that lives in or drinks that water.”
What Can Be Done?
For starters, upgrading wastewater treatment facilities would help a ton. Most of them weren’t built to handle chemical cocktails like this. There’s also talk of redesigning drugs so they break down more easily in the environment instead of sticking around like radioactive gum.
Bottom line: this study is a wake-up call. Not only do we need to stop turning our rivers into floating pharmacies, we also have to figure out what these drugs are doing to the animals living there—before the salmon start asking for a refill.
