Researchers have discovered that pharmaceuticals present in waterways are influencing the behaviour of aquatic animals, including fish such as Atlantic salmon. An investigation led by biologist Jack Brand at the Swedish University of Agricultural Sciences explored how drug pollution—stemming from human waste and pharmaceutical factory runoff—affects fish migration patterns.

The study focused on Atlantic salmon in Sweden, where increasing levels of pharmaceutical compounds have been detected in rivers and streams globally, with over 900 different pharmaceutical ingredients identified by scientists. Instead of exposing fish to these drugs through contaminated water, Brand’s team implanted pharmaceuticals directly into salmon to monitor the resulting behavioural changes under controlled conditions.

One of the notable findings concerned clobazam, an anti-anxiety medication. The salmon implanted with clobazam exhibited higher migration success towards the Baltic Sea. However, Brand cautioned against interpreting this as a straightforward benefit. “We can’t, you know, dump a bunch of pharmaceuticals into the river,” he said, emphasising the experimental nature of the research and the potential unintended effects of drug exposure on aquatic life.

In addition to migration improvements, the drug altered other behaviours: the treated salmon became bolder and less social. These changes could have complex implications for salmon in their broader ecosystem and life cycle, aspects that remain largely unknown. The long-term ecological consequences of pharmaceutical pollution on aquatic animal behaviour are still being studied.

This research highlights the growing concern over drug contamination in natural waterways and its impact on wildlife populations. Further investigations are needed to understand fully how exposure to human medications modifies animal behaviour and what that means for conservation and environmental health.

Source: Noah Wire Services