Cocaine-exposed salmon become unstoppable swimmers, new study finds

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Cocaine found in rivers and streams may be affecting wildlife behavior. A recent study showed that salmon exposed to cocaine swam much greater distances than usual, suggesting the drug is having an impact.

Scientists studying Atlantic salmon in Lake Vättern, Sweden, found that fish exposed to chemicals similar to cocaine became increasingly energetic over time.

After the study concluded, some of the tracked animals were swimming almost twice the distance weekly and were found as far as 12.3 kilometers from their original release point.

Cocaine salmon outswim competitors

Researchers studied 105 young salmon for eight weeks, dividing them into three groups: one exposed to cocaine, another to a substance created when cocaine breaks down, and a control group that received no drugs. Initially, all the fish behaved the same, but their behavior soon began to diverge.

Unlike healthy salmon, which tended to stay near where they began, the salmon exposed to the drug continued to swim and traveled a greater distance across the lake.

The most significant effect was caused by benzoylecgonine, a substance created when the body processes cocaine. It’s also a frequent contaminant in rivers and lakes because wastewater treatment plants aren’t always able to filter it out completely.

This significantly affects life in the water, influencing everything from how animals find food to how they stay safe from predators. Scientists are still trying to understand the long-term consequences, particularly for animals living in the wild.

It’s not only salmon affected by drug contamination. A recent study from March 2026 also revealed that sharks in the Bahamas contained traces of cocaine, caffeine, and everyday pain relievers.

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2026-04-23 12:50