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Overfishing Is Emptying The World’s Oceans Of A Vital Nutrient Supply: Fish Pee

Eating all the big fish means depriving coral of their big bladders

Image via Flickr, USFWS

Unless you’re seven years old with a brand new goldfish, you probably don’t spend a lot of time thinking about fish pee. As it turns out, fish urine should be at the forefront of our minds since it aids marine biodiversity. And lately, there hasn’t been enough to go around as a result of our insatiable human demand for big fish—aka the big bladders that help the ocean go round.


In a study published in Nature Communications last Tuesday, author Jake Allgeier argues that overfishing has widespread consequences for the natural nutrient cycle that regulates biodiversity but also coral reef health. Allgeier, who’s a postdoctoral researcher at the University of Washington, said in an interview with National Geographic, “It’s kind of a funny thing to say that we would conserve for fish pee. But it is hopefully setting a precedent to think about these reefs differently.”

According to Allgeier’s in-depth research of Caribbean reefs, a delicate recycling process dictates how corals form, survive, and ultimately process nutrients back into a cyclical food chain. Without fish urine, coral reefs have a hard time gathering vital nutrients, which makes sense seeing as they can’t swim in search of alternative food sources.

The process for figuring out how much a fish pees is a pretty brutal one that involves trapping fish in seawater-filled bags, analyzing the water, and then freeze-drying the water to be crushed into a powder. According to National Geographic, coauthors Abel Valdivia and Courtney Cox (the marine biologist, not the Cougar Town actress) cataloged 143 different species of coral from 43 different reefs to analyze the relationship between coral and fish. The team found that while heavily fished areas did not greatly reduce the number of species, the lack of big fish slashed the amount of pee reaching the reefs.

The study’s authors hope this information helps people better understand the delicate balance that keeps our oceans functioning.