Barotrauma
What Is Barotrauma?
Fish that are caught in deep water and then released may face additional challenges to survival. Some marine fish, such as snappers and groupers, have a gas-filled organ called a swim bladder that controls buoyancy and allows the fish to maintain a certain depth. When fish are pulled up from deep water (typically depths greater than 50 feet), the change in pressure can cause the gas in the swim bladder to expand and in some cases burst. Damage to the swim bladder or other organs that is caused by this change in pressure is called barotrauma.
Symptoms of Barotrauma
Symptoms of barotrauma can include the stomach protruding from the mouth, intestines protruding from the anus, bulging eyes, bubbling scales, flared gills, bloated belly, and floating at the surface or the inability to swim down.
Photos courtesy of Return 'Em Right.
Releasing a Fish with Barotrauma
When a fish suffering from barotrauma is released, it may be unable to swim back down to its captured depth, making it more susceptible to the elements and predators. This leads to discard mortality, or death after release, which is a leading concern of reef fishing.
If a fish needs to be released and shows any of these signs of barotrauma, the quick and proper use of a descending device or venting tool can help fish get back down to depth and improve their survival. Though both descending devices and venting tools can help improve the survival of released fish, research has shown that descending devices are the most effective method to treat barotrauma and reduce mortality.
Watch this video to learn how to treat barotrauma. Read about FWC’s 2017 FWC Citizen Science Descending Device Study Final Report - An Evaluation of Anglers' Barriers to Using Descending Devices.
Return 'Em Right
A program providing education and free gear to eligible offshore anglers.
How to Use a Descending Device/Venting Tool
Descending Devices
Photo courtesy of Return 'Em Right.
A descending device (recompression device) is a tool that is used to help reverse the effects of barotrauma. The device descends the fish back down to a depth where the increased pressure from the water will recompress the swim bladder gases and allow the fish to swim away.
There are three main types of descending devices, lip clamps, inverted hooks, and fish elevators. All need to be used with weights to help the fish get back down to depth. It is recommended to use one pound of weight for every five pounds of fish to be descended. Use a combination of loop knots, swivels, snaps, clips, etc. to attach the weights and device to your line. Be able to quickly and easily add or remove weights as needed, based on the size of the fish being descended and the water conditions. These devices should be used with a heavy-duty rod or handline.
The type of descending device is often based on individual angler preference and conditions. Find the device that works best for you. If you choose to use a descending device, follow the instructions on the package carefully to ensure the device is used properly. Watch our descending devices playlist to learn more.
Where to Get a Descending Device
Some descending devices are available in retail shops, or you can even make your own device. If you are unable to locate the device you want from a local store, you can also find various models for sale online.
If you are a Gulf of Mexico reef fish angler who fishes for federally managed Gulf of Mexico reef fish, you may be eligible for free gear from Return ‘Em Right by taking their online training of best fishing practices.
Lip Clamp
Photo courtesy of Return 'Em Right.
Lip clamps can either be pressure triggered or spring triggered. A pressure triggered lip clamp attaches to the fish’s bottom jaw and can be set to a specific depth for release. Once the device has reached the pre-specified depth, it will automatically open, releasing the fish. A spring triggered lip clamp will require you to manually release the clamp by jerking up on the rod once the fish reaches the desired depth.
Learn how to use SeaQualizer and RokLees descending devices.
Inverted Hook
Photo courtesy of Return 'Em Right.
An inverted hook descending device is a barbless hook that is inserted either into the original hook hole or through the soft tissue under the fish’s lower jaw. Once the fish has descended to the desired depth, reel up and the hook will slide out of the fish’s mouth. In some circumstances you may need to jig your line to release the fish.
Learn how to use Fish Saver and Shelton Fish Descender devices. Learn how to make your own inverted hook descending device.
Fish Elevator
A fish elevator is a weighted container that can help take fish back to depth. These can be weighted crates, baskets, or cages and can release multiple fish at one time. Place fish in the container and descend to the desired depth. Depending upon the container, you may be able to simply reel the device back in, others with doors may require you to jerk the line to open the container.
Learn how to use a milk crate descending device.
Venting Tools
Photo courtesy of Return 'Em Right.
Venting tools are sharpened, hollow instruments designed to release expanded gases in the body cavity of a fish experiencing barotrauma, enabling the fish to swim back to capture depth after release. A variety of venting tools are available at tackle stores and online, but the tool must be hollow and sharp. Knives, ice picks, and hooks are not legal venting tools and will cause additional damage to the fish you are releasing.
Anglers must also confidently understand exactly where to use a venting tool so that no internal organs are injured further. Never pierce the protruding stomach or intestines of a fish experiencing barotrauma.
How to Vent
Where to vent a fish
If you are using a venting tool for barotrauma mitigation, it is important to work quickly and effectively. Place the fish on a cool, wet surface. Gently hold the fish on its side and lay down the pectoral fin. This marks the location of where to vent the fish, approximately two to three inches past the base of the pectoral fin. Insert the needle under a scale into the body cavity at a 45-degree angle until a hissing sound is heard.. Once the hissing sound stops, remove the venting tool and release the fish headfirst into the water.
Remember to only use a venting tool or descending device when one or all of the signs of barotrauma are present. Watch this video to learn how to vent a fish properly.
How to Treat Barotrauma
Learn about the tools available to treat barotrauma, a condition that occurs when fish are brought up from deep waters. Knowing how to and using venting tools and descending devices can help fish survive after being released.
Watch VideoFish Handling & Gear
There are a lot of things you can do to give the fish you are releasing a fighting chance!