Don’t do the Dew; carbonation doesn’t help revive injured fish

The best thing an angler can do to ensure survival of a caught bass, whether bleeding or not, is to release it or put it in a well-aerated live well as quickly as possible. (Photo courtesy Gene Gilliland)

I first heard of tournament anglers pouring Mountain Dew over the gills of bass to stop bleeding about 30 years ago. The trick of pouring carbonated beverages into the mouths or over the gills has also been adopted by pike and muskie anglers — maybe by other angler groups, too. Like all dock talk, some you can believe, some you can’t.

John Anderson, an accomplished muskie guide, had adopted and championed the use of carbonated beverages to stop gill bleeding.

Always inquisitive, he enlisted Dr. Steven Cooke at Carleton University in Ottawa and facilitated funding to test the potential benefits.

The study by fishery scientists in Cooke’s lab, at the University of Manitoba and the University of Massachusetts, was published this year in the North American Journal of Fisheries Management. It concluded there was no benefit to the use of carbonated beverages to stop bleeding.

Pop and pike

The experiment was simple. Northern pike were captured by angling when water temperatures were 52° to 64° F. Those not injured nor bleeding were retained for the experiment. A small, 3/8-inch-long piece of one gill arch and attached gill filaments was removed.

The now-injured and bleeding fish were then subjected to one of four treatments: held in lake water (control) or either carbonated lake water, or had Coca Cola, or Mountain Dew poured over the wound.

The time to stop bleeding did not differ among the treatments; indeed, the average time to stop bleeding — 193 seconds — was almost identical among the treatments. The study tested 118 pike, a sufficient number to achieve reliable results.

“Dewing” bass

The ultimate judgement of any fish-handling procedure is whether the fish survives to reproduce and be caught again. The well-done pike study, like most other fish-handling studies, did not monitor long-term survival. Thus, the mortality due to injured and bleeding gills remains unknown.

However, a study by Steven Bardin, owner of Texas Pro Lake Management, a private lake-management service in Texas, tested carbonated beverages on largemouth bass and provided insights about long-term survival.

Bardin used 30 largemouth bass collected by electrofishing. All fish were sedated before treatment. For 10 of these fish, Bardin made a cut in the gills with a fish hook and released the fish into a small, hatchery pond.

Ten other bass had the gills similarly cut and soda poured over the gills until the bleeding appeared to stop before release into the pond.

The last group of 10 fish — the control — was released into the pond uninjured.

Water temperature was in the mid-60s. All fish were marked so the groups could be distinguished when recaptured.

The pond was fished daily. After 14 days, all fish were caught. Or more to the point of the experiment, all fish survived.

Conclusion: bass with a minor injury to the gills with or without carbonated beverage treatment survived as well as uninjured bass.

Helping anglers achieve high survival of caught-and-released bass is important to pond manager Steve Bardin’s success and the pond owners’ satisfaction. Bardin found no benefit of using carbonated beverages to stop gill bleeding. (Photo courtesy Steve Bardin)

Dew it or not

So, carbonated lake water or beverages don’t help stop bleeding. But they don’t hurt either, right? Well maybe or maybe not; the contemporary knowledge of how fish gills work is still insufficient to draw a solid conclusion.

But here’s what is known. The elevated carbon dioxide (the source of carbonation), which can be detected by the gills, can cause constriction of blood vessels and bradycardia (slowing of heart rate, not a good condition) that would transiently reduce bleeding.

Holding the fish out of water to pour the beverage over the gills, which reduces oxygen uptake (not a good condition), also triggers bradycardia. But tissue damage also stimulates blood coagulation, and the acidity of the carbonated water or beverage can cause gill tissue damage. Bardin observed his bass, although sedated, had a muscular response when the soda was poured over the gills, suggesting a noxious stimulus and possible adverse effect on the fish. The high carbon dioxide in the soda also can infuse into the blood and cause cascading physiological adjustments.

Bottom line: immersion of northern pike, largemouth bass and probably other gamefish in lake water stops bleeding just as effectively as those doused with soda, and it eliminates additional and potentially harmful handling and treatments.