Researchers try to reduce barotrauma deaths for deep-sea fish and sustain industry

By doing so, anglers would play a key role in sustaining the state's valuable fisheries.

When anglers reel in their catch from deep waters, fish can suffer problems caused by gas pressure changes -- or barotrauma. Often the gas-filled swim bladder of the fish has ruptured, releasing the gas into the fish's body cavity. Symptoms of barotrauma include the stomach protruding from the fish's mouth, bulging eyes, a bloated belly and distended intestines. Fish with these symptoms find it hard to swim back down to their natural habitat, and many die as a result.

Mitigating this condition may be a key to maintaining Florida's fisheries, said Chuck Adams, a marine economist with Florida Sea Grant. The importance of reducing this source of mortality for fish is further underscored by a recent UF/IFAS report that showed fishing and seafood products have a $565 million-a-year impact on Florida's economy. That report can be found here: www.edis.ifas.ufl.edu/fe969.

To bridge the gap between what Florida saltwater anglers know about barotrauma and how to lessen its impact, UF researchers surveyed the fishermen themselves.

In 2014, they emailed a survey to Florida anglers with saltwater fishing licenses. Of the 739 who responded, 70 percent said they noticed some of the classic barotrauma symptoms, said Adams, who holds a dual appointment with the UF/IFAS food and resource economics department and the Florida Sea Grant program. Adams worked with Sea Grant colleagues on the survey, the findings of which they hope will help fisheries managers better understand barotrauma and encourage anglers to use methods to release fish so they may survive the effects of barotrauma.

Most respondents said they have tried to return fish to the water. Nearly all respondents used a venting tool -- essentially a hollow-needle syringe with the plunger removed. Properly inserting the needle releases gases trapped in the body cavity of deep-water reef fish, allowing them to swim back to their normal depth. Most anglers suggested they need more information or training on how to do so effectively, Adams said.

Researchers also found they need to train fishermen how to use descending tools to return fish to depth. Descending tools are weighted devices that attach to the mouth of the fish, pulling them back to depth.

So, while many anglers know about barotrauma and how to spot it, they may not know how to treat it, Adams said.

"These and other key findings suggest an educational opportunity exists with the reef-fish angling sector to provide a greater understanding of what barotrauma is and why it occurs, and how to possibly reduce the mortality associated with releasing reef fish," Adams said. "Widespread awareness of barotrauma mitigation methods will help fisheries managers achieve their goals of achieving sustainable use and the maximum economic value of reef fish."

Adams presented the team's findings at the Florida Sea Grant Coastal Science Symposium in Gainesville on Sept. 15. Another member of the team, Joy Hazell, recently presented the findings at the 2015 meetings of the American Fisheries Society in Portland, Oregon. Other members of the investigative team were Florida Sea Grant Extension agents Bryan Fluech, Elizabeth Staugler, Lisa Krimsky and John Stevely (retired).