How to Safely Release Deep-water Fish

July 2020

By Fish and Wildlife Conservation Commission

It’s the time of year to fish for snapper and grouper, and you can continue your role as a conservationist by looking out for signs of barotrauma when releasing deep-water fish.

Barotrauma is a condition in many fish caught at depths greater than 50 feet. It comes from pressure changes during the hooked fish’s ascent, which leads to an expansion of gases in the swim bladder. Signs of barotrauma include the stomach coming out of the mouth, bloated belly, distended intestines, and bulging eyes.

Barotrauma can cause damage to internal organs and can be fatal unless sportsmen take appropriate steps to save the affected fish. It’s important to know in advance what tools are available and how to use them to help fish return to the bottom and increase their chances of survival.

Descending devices – These take fish back down to a depth where increased pressure from the water will recompress swim bladder gases. They fall into three categories: mouth clamps, inverted hooks, and fish elevators. With proper setup and practice, descending devices can be easy to use and make a big impact on the survival of released fish.

Venting tools – These sharpened, hollow instruments treat barotrauma by releasing expanded gas from the swim bladder, enabling the fish to swim back down. Please note, items such as fillet knives, ice picks, screwdrivers, and gaffs are not venting tools and should never be used to vent a fish. Venting a fish incorrectly may do more harm than good.

To properly vent, lay the fish on its side on a cool, wet surface. Venting tools should be inserted 1-2 inches behind the base of the pectoral fin, under a scale, at a 45-degree angle, just deep enough to release trapped gases. Never insert venting tools into a fish’s belly or back. Also, stay away from a stomach that is protruding from the mouth.

You should only use descending devices and venting tools when fish show one or more signs of barotrauma and cannot swim back down on their own. It is essential to work quickly when using these tools and return the fish to the water as soon as possible. Anglers should choose the device and method they are most comfortable with and that best fits the situation.

Anglers should also use proper gear when fishing for reef fish. Non-stainless steel inline (non-offset) circle hooks with the barb crimped down often hook in the mouth rather than the gut, making it easier to release fish. De-hooking tools also help in releasing fish so you can get back to fishing for that big one in no time.

To learn more about proper fish handling techniques, visit the Florida Fish and Wildlife Conservation Commission. Check out our descending devices playlist to learn more about barotrauma, descending devices, and venting tools.