We often see the effects of human pollution in plastic overloads and ocean fires, what we don’t see so much are the meth-addicted fish.
According to new research, brown trout can become addicted to methamphetamine when it accumulates in waterways.
Researchers set out to investigate whether illicit drugs can alter fish behaviour at the levels found in waterways.
“Whether illicit drugs alter fish behaviour at levels increasingly observed in surface water bodies was unclear,” said Pavel Horky, a behavioural ecologist from the Czech University of Life Sciences Prague.
The researchers put 40 brown trout in a tank of water containing a level of methamphetamine that has been found in freshwater rivers for eight weeks.
They then transferred the fish to a clean tank to see if the trout showed signs of methamphetamine withdrawal.
It turns out that the trout were suffering withdrawal because they sought out the drug when the researchers gave them a choice between water containing the drug, or water without.
The researchers also found that during the withdrawal period, the meth-exposed trout moved less, which was interpreted as a sign of anxiety or stress – typical signs of drug withdrawal in humans.
Sewers are loaded with drugs that have been excreted from the body, and because sewerage treatment plants aren’t able to filter them out, they can creep into waterways inhabited by millions of oceanic species.
“Fish are sensitive to adverse effects of many neurologically active drugs from alcohol to cocaine and can develop drug addiction related to the dopamine reward pathway in a similar manner as humans,” Horky told CNN.
“Such effects could change the functioning of whole ecosystems as adverse consequences are of relevance at the individual as well as population levels.”
The situation is similar to when Australian police raided a crystal meth lab in 2016 to find a six-foot-long jungle python, which had absorbed drug fumes and particles through its skin
The snake showed visible signs of addiction when it snapped at police officers and later acted aggressively towards animal handlers during the raid.