What are Fish Descending Devices?
Florida Sea Grant begins project to increase survival of deep water released fish.
Experienced deep sea anglers are all too familiar with the problems of releasing fish (either undersized or out of season) caught in deep water. Fish retrieved from such depths (generally deeper than 60 – 80 ft.) experience problems caused by the rapid change in pressure. Gas in their swim bladders (used to control their buoyancy) expands and ruptures the bladder, releasing gas into the fish’s body cavity.
When this happens the fish appears bloated and cannot swim back down to the bottom, resulting in almost certain mortality. In severe cases, the gas trapped in the body everts the stomach, causing it to protrude from the mouth. It is a common misperception by anglers that this is the swim bladder, but it is the stomach.
Obviously, fishery management regulations that require release of fish will be ineffective if the released fish do not survive. To address this problem, federal regulations in the Gulf require anglers to vent fish that are unable to swim back to the bottom. Venting involves using a sharp hollow instrument to puncture the body cavity wall and release the expanded gases so the fish can return to depth and have an increased chance of survival. However, venting is not perfect. It can increase the survival of some, but not all fish species, and obviously results in some additional injury to the fish.
New on the horizon: fish descending devices
The problem of increasing survival of fish caught in deep water is not unique to southwest Florida, Gulf and Atlantic. In fact, it is fair to say it is a worldwide problem. Similar problems are encountered on the U.S. west coast for a group of bottom fish commonly referred to as rockfish. Along the U.S. west coast water as deep as 200-450 feet is easily in sight of land. Recent research on rock fish has shown that many species of these fish can survive if they are quickly returned to the bottom. A number of ingenious anglers have developed a variety of devices that can be used to accomplish this with minimum injury to the fish. Some of these devices have just come on the market in the past six to nine months.
Florida Sea Grant In Action
Florida Sea Grant Extension Agents are now conducting field trials to develop expertise in the use of these devices. Furthermore, we are conducting field trials with volunteer anglers to evaluate if these devices are practical and whether anglers will be willing to use them. The hope is that eventually fisher managers will be able to provide anglers with options on how best to get fish back down to the bottom to maximize their chances for survival. We must stress this work is experimental at this time and more research will be needed and is being planned.
Important note: Currently, in the Gulf, venting of fish that require assistance to return to the bottom is the only permissible method allowed. Descending devices can only be used after the fish is vented. We had to obtain an Exempted Fishing Permit to conduct this work. In my opinion, and I stress that at this time it is only my opinion, federal fishery resource managers will probably consider allowing anglers to use descending devices in the Gulf in the future. Use of all types of venting/descending devices is currently permissible in the Atlantic.
Click throughout slideshow for a sampling of some of the new devices. There are more constantly being developed and some anglers are coming up with homemade devices.