#Frantic, jumping salmon may have been high on cocaine

The strange, frantic behavior of salmon on a German fish farm may have an even stranger explanation — cocaine.

In June 2020, salmon exhibited erratic behavior in which they tried to jump out of the water in a panic at the Lanuv Kirchhundem-Albaum site in Sauerland. Upon investigation, analysts from the State Environment Agency of North Rhine-Westphalia (or Lanuv) detected cocaine and a cocaine degradation product in a running stream there.

“It was a response to a feeling of discomfort,” Daniel Fey, head of Fisheries Ecology and Aquaculture, told Der Spiegel magazine, suggesting that the behavior of the fish was indicative of water contamination.

A recently released annual report written in German included the wryly titled section “Salmon on Coke (Lachse auf Koks)” which discussed the investigation into why the fish may have been so hyperactive. The report noted that scientists tried to detect unknown pollutants introduced by humans, such as pharmaceuticals, pesticides, industrial chemicals and sewage treatment plant discharges.

To determine the unknown substances, water samples from the streams that led to the fish tanks were examined using a high-precision analyzer. After a few days, results revealed plant protection products such as herbicides from agriculture and pharmaceuticals in small quantities. But they were detected in such minute levels that there was no clear indication that they contributed to the salmon’s behavior.

However, “two conspicuous substances” were also discovered: cocaine and its breakdown product benzoylecgonine. The analysts did not find the substances in the fish tanks, although this could be attributed to a high degree of dilution in the tank. Thus researchers could not determine fully why the fish frantically jumped around, although a reaction to cocaine cannot be ruled out, according to the report.

“Evidence of a multitude of other trace substances also shows that humans leave their footprints everywhere — even in streams near the source in very sparsely populated regions like the Sauerland,” the report said.

To determine where the cocaine actually came from, Lanuv employees searched for and came across an illegal sewage discharge at the stream, which was reported to authorities. A spokesman for the Olpe district police said that there was no concrete indication of the area from which the cocaine spawned, although Vice reported that drug gangs and manufacturers dump toxic chemicals and waste into local waterways across Europe.

However, Fey noted that “the next day [the salmon] showed typical behavior again,” and the salmon showed no signs of permanent health damage.

Drug-polluted waters have had more serious repercussions for other aquatic animals. A 2018 study found that endangered eels high on cocaine may struggle to mate. Party drugs such as cocaine and ketamine were also found in freshwater shrimp in the UK in 2019. And brown trout can even become addicted to the illegal drug methamphetamine when it accumulates in waterways, according to a Czech study.