Skip to main content

Barotrauma: It's All About Laws

Barotrauma: It's All About Laws

Physics in Fish—Bringing fish to the surface from deep water can cause damage to their eyes and internal organs. The extent of damage depends somewhat on depth range, species of fish, and physiological state of the fish.

The causes of this damage, called barotrauma, are based on two important laws of physics, Boyle’s Law and Henry’s Law. Boyle’s Law, defined by Robert Boyle, an Irish scientist, in the 1660s, relates to the relationship of pressure and volume of a gas. It states that within a closed system at constant temperature, the volume of a gas is inversely proportional to the pressure acting on that volume. When pressure is cut in half, volume is expected to double. Related injuries include ruptured swim bladders and exopthalmia (bulging eyes), everted stomach or intestine, internal hemorrhaging, and gas bubbles in the organs.

Henry’s Law, derived by the English chemist William Henry in 1803, states that at a constant temperature, the amount of a gas that dissolves in a type and volume of liquid, such as blood, is directly proportional to the partial pressure of that gas in equilibrium with that liquid. When pressure surrounding a fish is reduced, the dissolved gas can come out of solution, resulting in gas bubble formation. This is the mechanism that can cause “the bends” in scuba divers who ascend too quickly. For fish, it most commonly occurs when they suddenly pass through the areas of low pressure created by turbines at hydropower dams, causing blood and bodily fluids to become supersaturated, allowing gas bubbles to form. Bubbles grow as pressure drops, which can cause internal hemorrhaging.

Carbonated drinks give an everyday example of Henry’s Law. In an unopened can, the gas above the drink is almost pure carbon dioxide, kept at a pressure slightly greater than atmospheric pressure. And the drink contains dissolved carbon dioxide. When the can is opened, gas escapes, producing a hiss. Because the partial pressure of the carbon dioxide above the liquid is reduced, carbon dioxide comes out of solution as bubbles. Left out, the drink becomes “flat” when the carbon dioxide in solution comes into equilibrium with the carbon dioxide in the air.


Barotrauma problems associated with Boyle’s Law most often affect fish species with a closed duct between the swim bladder and esophagus, such as bass, walleyes, perch, and crappies. Salmonids, catfish, and other species with a duct, are more often damaged during extremely fast decompression, such as young fish passing through a dam. They generally can expel gas by belching when brought to the surface by an angler.


Keep these physics principles in mind if you fish deep for bass, walleyes, perch, or crappies. Damage can occur when fish are raised as little as 20 or 25 feet. Because internal tissues are elastic, they can stretch somewhat before breaking so swift release can sometimes prevent permanent damage. It’s a common fallacy that raising ductless species slowly prevents barotrauma. It does little good, as gas release for them requires hours rather than minutes. Rather, raising them quickly and releasing them immediately might work better to reduce barotrauma effects.

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

See More Recommendations

Popular Videos

The True Story of the Bass Boat Hero Who Broke the Internet

The True Story of the Bass Boat Hero Who Broke the Internet

“If that engine starts without my kill switch on, I ain't the one driving it,” Blake Broussard says after ejection video goes viral.

Hobie MirageDrive 360 Kayak Propulsion: Amazing Control and Power

Hobie MirageDrive 360 Kayak Propulsion: Amazing Control and Power

The Hobie MirageDrive 360 pedal propulsion system is the pinnacle of kayak control with more efficient fin designs, glide technology and allows the boat to be moved in any direction.

Channel Cats on Ice

Channel Cats on Ice

The In-Fisherman staff reveals some of the hottest action of the winter season, as they show how to ice 20-pound channel catfish.

Lake Superior Whitefish on Ice

Lake Superior Whitefish on Ice

Doug Stange joins Capt. Aron Kastern on Lake Superior near Ashland, Wisconsin where they go after whitefish on ice.

See More Popular Videos

Trending Articles

You're going to love this Beer-Battered Fish Fingers Recipe! These deep-fried walleye strips are tasty and dress up nicely when served in a basket or on a plate with fresh fruit such as grapes and strawberries.Beer-Battered Fish Fingers Recipe Fish Recipes

Beer-Battered Fish Fingers Recipe

In-Fisherman

You're going to love this Beer-Battered Fish Fingers Recipe! These deep-fried walleye strips...

One angler's forgotten, overlooked, underutilized musky lure is another fisherman's all-time favorite.Forgotten (Or Temporarily Overlooked) Muskie Lures Pike & Muskie

Forgotten (Or Temporarily Overlooked) Muskie Lures

Cory Schmidt - August 25, 2020

One angler's forgotten, overlooked, underutilized musky lure is another fisherman's all-time...

To guide your carp quest, we've lined up the best carp baits that are easy-to-fish natural baits and commercial options.10 Best Carp Baits Available Today Carp

10 Best Carp Baits Available Today

Dan Johnson

To guide your carp quest, we've lined up the best carp baits that are easy-to-fish natural...

Introduced species often directly or indirectly adversely affect native species.Questioning Fish Introductions Other Fish

Questioning Fish Introductions

Dr. Hal Schramm - July 06, 2020

Introduced species often directly or indirectly adversely affect native species.

See More Trending Articles

More Critical Concepts

Attaining a measure of efficiency in any given situation is a vital part of successful fishing.Balancing Tackle & Fish Talent Critical Concepts

Balancing Tackle & Fish Talent

In-Fisherman - December 26, 2019

Attaining a measure of efficiency in any given situation is a vital part of successful fishing.

Researchers recently evaluated post-release survival of walleyes.Ice Fishing and Walleye Survival Critical Concepts

Ice Fishing and Walleye Survival

Gabe Gries

Researchers recently evaluated post-release survival of walleyes.

Fishing gets difficult under such conditions, but fortunately, Turnover lasts only about a week on any one lake.Understanding the Fall Turnover Period Critical Concepts

Understanding the Fall Turnover Period

In-Fisherman

Fishing gets difficult under such conditions, but fortunately, Turnover lasts only about a...

Do UV lures have “brightening” benefits under ice?UV Light on Ice and Open Water Critical Concepts

UV Light on Ice and Open Water

Dr. Rob Neumann - November 21, 2019

Do UV lures have “brightening” benefits under ice?

See More Critical Concepts

Magazine Cover

GET THE MAGAZINE Subscribe & Save

Digital Now Included!

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW THIS MONTH'S ISSUE Arrow

Buy Digital Single Issues

Don't miss an issue.
Buy single digital issue for your phone or tablet.

Buy Single Digital Issue on the In-Fisherman App

Other Magazines

Special Interest Magazines

See All Special Interest Magazines

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Phone Icon

Get Digital Access.

All In-Fisherman subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit mymagnow.com and learn how to access your digital magazine.

Get Digital Access

Not a Subscriber?
Subscribe Now