Here’s What Happens When You Give Salmon Cocaine

What do you think happens if you give salmon cocaine?

A group of scientists tried it.

Authors of a new study surgically implanted devices

that slowly released chemicals

into 105 juvenile Atlantic salmon in Lake Vattern in Sweden.

Why?

Well, cocaine and its metabolites

are being detected globally in rivers and lakes

with increasing frequency,

entering waterways primarily

through wastewater treatment systems.

And although previous research had shown

that cocaine pollution can affect animal behavior,

the evidence prior to this study

was limited to laboratory conditions.

The fish were divided into three groups:

a control group that got nothing,

a group exposed to cocaine,

and a group exposed to benzoylecgonine,

the main metabolite of cocaine

that is commonly detected in wastewater.

Through small tags the scientists had attached to the fish,

they found over a two-month period

that compared with the control group,

the fish exposed to benzoylecgonine

swam up to 1.9 times farther,

dispersing at the end of the experiment

about 20 miles from the release point.

The findings provide the first evidence

that the effects of cocaine contamination on fish behavior

occur not only under lab conditions,

but also in the wild, where animals are exposed

to much more complex environmental conditions.

The study also found

that the most pronounced effect was observed

not so much in the group exposed to cocaine itself,

but in the fish exposed to its metabolite.

The next step for research is to determine

how widespread these effects are,

as well as identify species most at risk

and test whether alterations in behavior

translate into changes in survival and reproduction.