Barotrauma presents a challenge for fish, particularly bass, when rapidly brought to the surface from deeper waters. This condition involves injuries caused by sudden changes in pressure, which can impact a fish’s health and survival. Understanding barotrauma is important for recreational anglers, as it promotes responsible fishing practices and supports fish conservation efforts.
Understanding Barotrauma
Barotrauma refers to physical damage sustained by a fish due to rapid changes in ambient pressure. It primarily affects the swim bladder, a gas-filled organ in the abdominal cavity of bony fish, including bass. Its main function is to regulate buoyancy, allowing fish to maintain position at various depths without expending excessive energy.
The problem arises because internal swim bladder pressure cannot equalize quickly enough with decreasing external water pressure as the fish is reeled upwards. Bass are physoclistous species, meaning their swim bladder is a closed system, not connected to the digestive tract. This prevents them from rapidly releasing excess gas, making them more susceptible than fish with an open connection.
How Rapid Depth Changes Induce Barotrauma in Bass
Boyle’s Law explains barotrauma: as pressure decreases, gas volume increases. As a bass is pulled from deep water towards the surface, the surrounding water pressure significantly drops. For instance, pressure increases by approximately one atmosphere for every 33 feet of depth. This pressure reduction causes the gas inside the bass’s swim bladder to expand considerably.
This rapid expansion can lead to a range of severe internal injuries. The overinflated swim bladder may rupture, or its extreme expansion can displace or compress surrounding internal organs. Gas can also escape into other body cavities, causing hemorrhaging of internal organs, fluid accumulation, or hematomas. Such injuries often occur in bass caught from depths greater than 33 feet, with more severe cases observed from depths exceeding 50 or 90 feet. Common scenarios include rapid retrieval during fishing, especially when targeting bass in their deeper habitats.
Identifying Signs of Barotrauma
Bass suffering from barotrauma exhibit several visible and behavioral indicators. A common sign is a distended or bloated belly, resulting from the expanded swim bladder. Eyes may bulge noticeably (exophthalmia) due to internal pressure.
Another clear indicator is an everted stomach, where the stomach protrudes from the fish’s mouth. Behaviorally, bass often lose equilibrium, appearing disoriented or swimming sluggishly. They may struggle to swim back down, floating on their side or upside down at the surface, making them vulnerable to predation or further environmental stress.
Strategies to Mitigate Barotrauma
Anglers can employ several strategies to reduce the incidence and severity of barotrauma in bass. Minimizing the time a fish spends out of water and handling it gently are important steps. Using appropriate de-hooking tools also helps reduce stress and injury during the release process.
Two methods treat barotrauma: venting and recompression. Venting, or “fizzing,” involves carefully puncturing the fish’s swim bladder with a sharp, hollow needle to release excess gas. This procedure should be performed precisely, behind the pectoral fin at a shallow angle, to avoid damaging other organs.
Recompression, using descending devices, offers a less invasive alternative. These tools (such as weighted clamps, inverted hooks, or fish elevators) attach to the bass and lower it to a sufficient depth (usually 60 feet or more), where increasing water pressure naturally re-inflates the swim bladder. Once at depth, the device releases the fish, allowing it to swim away and recover. Descending devices are recommended as they reduce handling stress and avoid harm from improper venting.