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Do carbonated beverages reduce bleeding from fish gill injuries?

  • 11/16/2021 9:33:00 AM
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From the Summer 2021 issue of Iowa Outdoors magazine

Let’s burst this bubble and see if it is fizz or fact.

Releasing fish due to size limits or for catch-and-release practices has anglers trying new methods to help severely hooked fish. Fish hooked in the gills have lower survival chances. Some anglers say pouring carbonated water or soda pop over hooked gills helps. They claim the carbon dioxide causes blood vessels to constrict or that phosphoric acid in beverages causes blood to clot.

A new study by Canadian researchers looked into the practice. Does it work? Or is blood clotting or reduced bleeding caused by increased tissue damage from the soda? It was the first study to determine if pouring fizzy drinks over bleeding hook injuries is truly a best practice for catch and release.

The Canadian researchers looked at two groups of northern pike caught in waters between 52 and 64 degrees Fahrenheit and 75 to 80 degrees Fahrenheit. They tested fish with carbonated lake water, Mountain Dew and Coca-Cola at temperatures to mimic anglers using beverages from an iced cooler or not. They also had a control group of fish with no gill injuries and using no carbonated beverages.

All fish were monitored for 20 minutes in a live tank to monitor bleed time, intensity and gill color to gauge blood loss. They judged likely fish survival based on reflex activity, eye tracking and other reactions. They tested 156 fish.

The study showed soft drinks were all wet. No evidence bubbled up that pouring beverages over gills was beneficial. Instead, any perceived bleeding reduction observed by anglers may be due to holding fish out of water longer to make the pour. Fish out of water have reduced oxygen, slower heart rates and temporarily reduced blood flow. It also stresses fish. Plus, acids found in carbonated beverages may damage gills.

So save your beverages. Fish weren’t designed to “Do the Dew,” and “Coke Adds Life” may be a fish tale. Catching and quickly releasing fish for their own respiration is still the best practice. The fish will drink to that!