Tips to Reduce Catch-and-Release Mortality
Floaters around your boat? You can help save them by descending them back down!
Rhode Island marine anglers who fish the deeper water are often faced with looking over the side of the boat and seeing their released fish bobbing around on the top of the water like floating balloons. This is not only unsightly; it causes mortality of released fish, and can leave a bad wasteful impression in an anglers mind after an otherwise successful fishing trip.
Descending devices are conservation tools that can be used to return fish to deep water and alleviate the “balloon” trail behind your vessel. Descending devices not only get the fish off of the surface, they can increase survival of the deep water caught fish that anglers wish to return to the water. They are becoming more common in use on the West, Gulf of Mexico, and South Atlantic Coasts, and could prove beneficial for some of our east coast fisheries, especially in the Mid-Atlantic Area, for black sea bass, tautog, and tilefish, all species that are typically caught in more the 60 feet of water.
When fish are brought up from deep water, they often suffer from barotrauma. Similar to the bends that scuba divers sometimes experience, barotrauma is the trauma caused by the expanding gases in the body from changes in barometric pressure as a body rises too rapidly to the surface. Fish with barotrauma effects, may look stiff and dead, have extended eyes (pop eyes), enlarged air bladder which results in the stomach forces out through the esophagus. Yes, that’s the stomach, not the air bladder. People often mistake the protruding stomach for the air bladder and puncture it, which is very injurious to the fish.
Barotrauma effects restrict a fish from swimming back down when released at the surface. Thus, it leaves them floating helpless on the surface subject to pry by birds, other fish, or dangerous surface conditions such as warmer water than they are used to. Some fish may eventually work their way back down, but, needless to say, many of these thrown back, bloated surface floaters, will not survive. To deal with the floaters, some anglers will “vent” the fish. Venting is done by sticking a needle into the side of the fish to puncture its body cavity and release the expanded gases in it. In many cases venting will allow the fish to swim back down, and is a quick way to reduce floaters if you are catching lots of fish that you need to release quickly. However, venting can leave the fish subject to internal injuries, infections, and attraction of predators.
Descending devices, in some cases, are a better method than venting. These devices allow you to return a fish to the depth you caught it, without puncturing and causing more serious injury. Simply getting the fish down to the depth it was taken from allows water pressure to expel, or recompress, the expanded gases in their bodies as they are descended, and many fish reassume normal behavioral activities quite soon after their underwater release. Studies on west coast rockfish have demonstrated high survival rates for descended fish with some fish surviving the barotrauma effects of being caught from hundreds of feet below the surface.
Some descending devices are simple tools that can be made at home with inexpensive materials. One such device is a weight with an inverted barbless hook (facing down) so it can be jerked upwards out of the fish when it reaches the bottom. Another easily constructed device to descend fish down is a weighted utility “milk” crate with a long rope. These are also available for purchase at some tackle shops or marine supply stores.
Very importantly, anglers who descend fish must not forget proper fish handling at the surface. Removing hooks quickly if hooked in the lip or mouth, or by cutting the line if the fish has swallowed the hooked to deeply, handling the fish gently as possible, and getting it back into the water quickly, will greatly enhance the ability of all released fish to survive, especially the ones that have to contend with barotrauma effects. NOAA reports that 60 percent of the fish caught by marine anglers are released back to the water (that’s 207 million fish in 2011). A common theme when requesting feedback from experienced anglers about their observations of the general fishing community is that the majority of anglers are not releasing fish correctly. Needless to say, greater conservation benefits would accrue to all or recreational fish stocks if more anglers would use proper fish release methods, and any efforts to reduce mortality by descending fish after poor surface handling would be less effective.
So, the next time you come across an old utility crate, consider putting some rope and weight on it, rig up your own inverted hook and weight release device, or take a look in a catalog for fish descending devices, and add them to your fishing gear. Try them out on your next deep water fishing trip. Most importantly, let the Rhode Island Marine Fisheries section and fisheries researchers know how useful and workable you find the devices. You then could consider yourself to be a Descender Pioneer for east coast conservation efforts to improve the release survival of deep water caught fish!
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