Using Best Fishing Practices When Heading Offshore – an FAQ 

Posted July 31, 2025

Barotrauma

Q. What is barotrauma?

Barotrauma is a pressure-related injury that can occur when fish are reeled up quickly from depth. In this ascent, gas can expand in the fish’s swim bladder, making it difficult or sometimes impossible for the fish to swim back to the depth it was captured. Deeper dwelling species, such as snapper and grouper, are especially vulnerable to barotrauma due to the pressure changes they experience in the water column as they are brought to the surface. Barotrauma is similar to the “bends” a SCUBA diver may experience when ascending too rapidly or the sinus pressure or ear popping a person may experience when flying. 

Fish such as salmon and trout have a duct connected to their swim bladder that allows them to “burp” air, which decompresses the swim bladder. Species such as bass, perch, snapper, and grouper do not have this duct, making them vulnerable to the injuries of barotrauma. Left untreated, barotrauma can greatly reduce a fish’s chance of survival after release. 

What are the signs of barotrauma?

One or more of these symptoms may indicate a fish is suffering from barotrauma: 

• Bulging eyes
• Stomach protruding from the mouth 
• Bloated or firm belly 
• Anal prolapse 
• Bubbling scales 
• Floating at the surface 

Q. How do you treat a fish with barotrauma? 

No one wants to see fish float off with little chance of survival. Luckily, there are ways to treat fish that are suffering from barotrauma. Two common tools used to treat barotrauma are descending devices and venting tools. A descending device is a tool that uses added weight to take fish back down through the water column and to their natural depth, allowing them to recompress in the descent. A venting tool is a sharp, hollow instrument used to puncture a fish’s swim bladder to release the excess gas. It is used by inserting the tool into the side of the fish at a specific location. Note: never puncture the stomach through the fish’s mouth! 

Q. What factors affect the severity of barotrauma? 

The severity of barotrauma varies based on several environmental and biological factors such as the depth of capture and water temperature. 

Supporting Research: 

• Depth of capture: Barotrauma can occur in fish caught in depths as shallow as 30 feet with the severity of barotrauma increasing with the depth of capture (Curtis et al., 2015). 

• Water temperature: Higher water temperatures, especially when there is a significant temperature differential between the depth of capture and the surface, can exacerbate the negative effects of barotrauma on fish. Higher surface temperatures can cause thermal stress in fish adapted to deeper, cooler waters and also correlates with low dissolved oxygen levels, which “could be detrimental to released fish when at a high respiratory demand” (Rummer, J. L., 2007). 

Descending Devices:

Q. How does a descending device work, and why should I use one? 

Descending devices are weighted tools designed to return fish showing signs of barotrauma back to their depth of capture. This helps the fish quickly recompress, a process that significantly improves their chances of survival. There are various designs of these devices on the market that are easy to use, and you can even make one yourself. Having a descending device onboard and ready for use is required when fishing for snapper grouper species in South Atlantic federal waters. 

Q. How effective are descending devices? 

The survival rate of a fish after a descending device has been used depends on many factors including the species, severity of barotrauma, stress, other traumas such as deep hooking, and environmental conditions such as temperature. However, studies consistently show that fish returned to depth using a descending device have a much higher chance of survival compared to fish released at the surface without treatment. Check out these research papers to learn more about survival rates of different species. 

Supporting Research:  

• Curtis et al. (2015) tagged 111 red snapper and found that descended fish were 3 times more likely to survive than non-vented fish, and 1.5 times more likely to survive than vented fish. 
•  Runde, B.J., & Buckel, J.A. (2018) tagged 19 deepwater grouper (i.e., scamp, snowy, speckled hind) finding a survival estimate of 50%. This may seem low; however, it is much higher than the 0% survival rate previously assumed. 
• Bellquist et al. (2019) conducted fishing charters in collaboration with central and northern California recreational fishing communities. Anglers caught and released 32 species of rockfish using five different descending devices. 2,275 rockfish were caught, with 2,079 being released alive, resulting in a 91.4% survival rate.  
• After studying 44 tagged red snapper off the coast of North Carolina, Runde et al. (2021) found an ~87% survival rate when a descending device is used to return fish to the sea floor. 

Q. Where can I buy a descending device? 

Many tackle shops carry some type of descending device. You can also make your own, often with the tools already in your tackle box. Learn more about making your own descending device that meets legal requirements here: https://safmc.net/best-fishing-practices/  

Q. What type of descending device is better? 

While all descending devices have the same function of quickly returning fish to depth, the type of device used is based on several considerations, such as fisherman preference, number of fish caught at one time, and the size of fish caught.  Explore the different types of descending devices in this Fishing Wire article by Sea Grant Reef Fish Extension and Communications Fellow, Greyson Webb. 

Q. What does it mean when a descending device is required to be “readily available”?  

When fishing for any of the 55 snapper grouper species  in federal South Atlantic waters (ranging from 3 to 200 nautical miles), a descending device is required to be readily available, meaning attached to at least 16 ounces of weight and 60 feet of line. This is because barotrauma worsens the longer a fish is at the surface, so returning them back to depth as quickly as possible is essential to their survival. This requirement applies to vessels fishing recreationally, commercially, and charter for-hire. 

While 16 ounces is the required minimum amount of weight, it’s recommended to use 1 pound of weight per 5 pounds of fish. 

Q. Should I use a descending device on every fish I catch? 

No. If there are no signs of barotrauma (stomach protruding from the mouth, bulging eyes, anal prolapse, or bubbling scales), that’s great! Use best practices when handling and releasing the fish and simply let it swim away. 

Q. How deep should I release fish? 

Ideally, fish should be released at the depth they are caught or as close to the bottom as possible. Not only does this allow fish to be properly recompressed, but it also greatly reduces the risk of a predator eating the released fish. 

Q. Are descending devices or venting tools better for treating fish suffering from barotrauma? 

Venting and descending devices are both effective barotrauma treatment methods that improve survival rates of fish experiencing barotrauma, but they must be done correctly.  

Because of the extensive list of descending device advantages, descending devices are now required to be readily available in South Atlantic waters when fishing for snapper grouper species. 

Supporting research: 

• Stallings et al. (2023) found that red snapper recompressed to 20 meters or more had a 2.5 times higher tag return rate compared to those fish that were vented.  

Q. Are fish more likely to be targeted by sharks when returned to depth with a descending device? 

Handling of Fish 

Q. Why does it matter how you handle and release a fish? 

How you handle and release a fish plays a critical role in its chances of survival. Excessive handling can cause both physical injuries—such as scale loss, fin damage, or internal trauma—and physiological stress, which can compromise recovery and increase the likelihood of post-release mortality. For example, dry hands and abrasive gear that come in contact with fish during handling can disrupt the fish’s protective slime layer, which often acts as a fish’s first line of defense against bacterial, parasitic, and fungal pathogens.  

Supporting Research: 

• Barthel et al. (2003) found that bluegill landed by hand had lower injury rates than those fish landed using a net. Conversely, all net types resulted in heightened injury and mortality with the knotted mesh types being more injurious than the rubber or knotless mesh. 
• A study by Powell A (2021) found that Atlantic salmon handled with landing nets with rubberized mesh showed significantly reduced scale loss than those handled with landing nets with non-rubberized mesh. 

Reducing handling time and keeping fish in the water as much as possible can also greatly improve the likelihood that a fish will survive past release. 

Supporting Research: 

• A study by Hager (2017) investigating post-release behavior and mortality of selected recreationally and commercially important snapper grouper species found that “handling time was the most important predictor of post-release behavior regardless of treatment. The faster a fish was able to return to depth, the higher the likelihood of survival, irrespective of the release method.
• Looking specifically at the effects of air exposure on post-release mortality, Graves et al. (2016) found that “the proportion of postrelease mortalities increased with air exposure duration.” They found that the overall rate of postrelease mortality was significantly higher for White Marlin that were subjected to air exposure (33.3%) than for those that remained in the water (1.7%). 

Q. How long is “too long” for a fish to be out of the water? 

While it is ideal for a fish to stay in the water prior to release, it is not always realistic. Sometimes, fishermen may need to pull the fish out of the water to remove a hook, measure it, or want to take a picture. If a fish is taken out of the water, it is important to minimize the amount of airtime. Have your gear readily accessible before the fish is on deck. This includes cameras, dehookers, measuring tapes, and of course, your descending device if needed. 

Supporting Research: 

• Cook et al. (2015) synthesized various research efforts, recommending less than 10 seconds of cumulative air exposure after a fish has been caught with plans of release. However, it was noted that there is no “one-size-fits-all” recommendation, as factors such as species, fishing trauma, and environmental factors can increase or decrease that recommendation.   

Hooks and Other Gear 

Q. Why are non-offset, non-stainless steel circle hooks required when using natural baits to fish for snapper grouper species north of 28 degrees N. Lattitude?  

Hooking depth, hooking location, amount of bleeding, and ease of hook removal are all factors which can influence a fish’s chance of survival following release. Non-offset, non-stainless steel circle hooks are required in South Atlantic federal water when fishing for or possessing snapper-grouper species north of 28 degrees N. latitude. Non-offset circle hooks have been found to be easier to remove than J-hooks, and as a result, produce shorter handling times, less bleeding, and less stress overall. Non-stainless-steel material degrades and sheds from fish at faster rates than hooks made of stainless steel or other non-corrodible metals in instances where the hook can’t or shouldn’t be removed. 

Supporting Research: 

• Snapper Grouper Amendment 16 synthesizes research that indicates that circle hooks produce lower mortality rates than J-hooks. For example: “Cooke and Suski (2004) found mortality rates were lower for circle hooks than J-style hooks…In many cases, circle hooks were found in the maxilla (jaw) and were less likely to be swallowed. Additionally, circle hooks were found less likely to result in bleeding than J-hooks, which tend to deep hook fish at a higher frequency (Cooke and Suski 2004).  
• Begue et al. (2020) found that stainless-steel and corrodible hooks had a retention half-life of less than 1 year with all corrodible hooks shedding within 2.5 years. On the other hand, embedded stainless-steel hooks persisted for at least 7.6 years and are “potentially retained for the lifetime of the shark.” 

Q. Do circle hooks work as well as J-hooks? 

While it can vary by species, studies have shown that fish can be caught with circle hooks at similar rates that they are caught with J-hooks. 

Supporting Research: 

• Garner et al. (2017) found that catchability was not significantly impacted by hook type, but catchability was impacted by hook size with catches decreasing “significantly with increasing hook size in all groups except red snapper.” 

Q. When should you leave a hook in instead of removing it? 

In the case where a fish is deeply hooked in the throat, gills or gut, it may be best to cut the line as close to the hook as possible and leave it in place. Extended handling and attempted hook removal may cause excessive damage to vulnerable areas and vital organs. Because non-stainless-steel hooks are required when fishing for snapper grouper species, fish should be more likely to shed the hook as supported in the research above.  

Supporting Research: 

• Fobert et al (2009) found that cutting the line is a more effective release method than removing the hook when fish are deeply hooked. In their study, deeply hooked fish that received line cut treatment had a mortality rate of 12.5% after 10 days while deeply hooked fish that had the hook removed had a mortality rate of 44% after 10 days. 

Q. Why should fishermen care about using best fishing practices? 

Whether you’re releasing a fish because it’s undersized, out of season, or just by choice, using best fishing practices helps ensure that a fish has a better shot at survival past release. A fish that goes on to survive past release is a fish that contributes to a healthy fishery while also giving you, and other fishermen, the opportunity to catch that fish another day. 

Supporting Research: 

• A study investigating post-release behavior and mortality of recreationally and commercially important snapper grouper species (Black Sea Bass, Red Porgy, Red Snapper, and Gray Triggerfish) found that “handling time and immediate release condition had significant effect on both the amount of time fish spent in normal swimming behavior and time it took fish to recover.” The same study found that “handling time was the most important predictor of post-release behavior regardless of treatment. The faster a fish was able to return to depth, the higher the likelihood of survival, irrespective of the release method” (Hager, 2017). 

Q. How can I provide scientists with information about the fish I release? 

The SAFMC is the only U.S. Regional Fishery Management Council with a dedicated Citizen Science Program that involves the public in scientific research. SAFMC Release is a citizen science project that partners with commercial, for-hire, and recreational fishermen to collect information on released shallow water grouper and Red Snapper using the free mobile app, SciFish. Data collected through the project includes length, depth caught, optional location, observations of shark predation, and use of barotrauma reduction techniques – like descending devices. These data can help scientists and managers better understand what species are being released, the size of released fish, and their likelihood of survival. Interested? Set up an account today by visiting https://safmc.wufoo.com/forms/z1xo8t300lpj5vu/. 

Do you have additional questions related to best fishing practices that were not covered in this FAQ? Check out our webpage at safmc.net/best-fishing-practices or email ashley.oliver@safmc.net.  

References 

Barthel, B.L., Cooke, S.J., Suski, C.D., & Philipp, D.P. (2003). Effects of landing net mesh type on injury and mortality in a freshwater recreational fishery. https://doi.org/10.1016/S0165-7836(03)00059-6 

Rummer, J.L. (2007). Factors affecting catch and release (CAR) mortality in fish: Insight into CAR mortality in red snapper and the influence of catastrophic decompression. https://repository.library.noaa.gov/view/noaa/42440/noaa_42440_DS1.pdf#page=124 

South Atlantic Fishery Management Council. (2008). Snapper Grouper Amendment 16. https://safmc.net/documents/snapper-grouper-amendment-16/ 

Fobert, E., Meining, P., Colotelo, A.H., O’Connor, C.M., & Cooke, S.J. (2009). Cut the line or remove the hook? An evaluation of sublethal and lethal endpoints for deeply hooked bluegill. https://doi.org/10.1016/j.fishres.2009.04.006 

Cook, K.V., Lennox, R.J., Hinch, S.G., & Cooke, S.J. (2015). Fish out of water: How much air is too much? https://doi.org/10.1080/03632415.2015.1074570 

Curtis, J.M.R., Taylor, J.C., & Rulifson, R.A. (2015). Quantifying delayed mortality from barotrauma impairment in discarded red snapper using acoustic telemetry. https://doi.org/10.1080/19425120.2015.1074968 

Graves, J.E., Horodysky, A.Z., & Kerstetter, D.W. (2016). Effects of air exposure on postrelease mortality rates of white marlin caught in the U.S. offshore recreational fishery. https://doi.org/10.1080/02755947.2016.1204390 

Garner, S.B., Stunz, G.W., & Vega, R.R. (2017). Experimental assessment of circle vs. J hook performance and selectivity in the northern Gulf of Mexico recreational reef fish fishery. https://doi.org/10.1093/icesjms/fsx001 

Hager, Z.F. (2017). Effects of venting and recompression on post-release behavior of snapper-grouper species. https://www.proquest.com/openview/d3d9bc00dc887ac996bd764c60a9f524/1?pq-origsite=gscholar&cbl=18750 

Runde, B.J., & Buckel, J.A. (2018). Descender devices are promising tools for increasing survival in deepwater groupers. https://doi.org/10.1002/mcf2.10010 

Bellquist, L.F., Stohs, S.M., & Semmens, B.X. (2019). Effectiveness of descending devices to mitigate the effects of barotrauma among rockfishes in California recreational fisheries. https://doi.org/10.1016/j.fishres.2019.03.003 

Begue, J.A., Meyer, C.G., & Holland, K.N. (2020). Prevalence, persistence and impacts of residual fishing hooks on tiger sharks. https://doi.org/10.1016/j.fishres.2019.105462 

Drymon, J.M., Froeschke, J., Powers, S.P., & Biggs, C. (2020). Descender devices or treat tethers: Does barotrauma mitigation increase opportunities for depredation? https://doi.org/10.1002/fsh.10476 

Powell, A. (2021). Rubber net mesh reduces scale loss during routine handling of farmed Atlantic salmon. https://doi.org/10.7120/09627286.30.1.019 

Runde, B.J., Buckel, J.A., & Reichert, M.J.M. (2021). Discard mortality of red snapper released with descender devices in the U.S. South Atlantic. https://doi.org/10.1002/mcf2.10175 

Runde, B.J., Buckel, J.A., & Reichert, M.J.M. (2022). Depredation of demersal reef fishes released with descender devices is uncommon off North Carolina, USA. https://doi.org/10.1002/nafm.10815