Bass, like most fishes, adjust their buoyancy so they can maintain their vertical position in the water without actively swimming. Bass adjust their buoyancy by the gas bladder. The gas bladder in fish operates like a buoyancy compensating device (BCD) used by a SCUBA diver. As depth increases, pressure increases and the gas compresses (occupies less volume.) The compressed gas provides less buoyancy. To maintain neutral buoyancy, the fish adds gas to the gas bladder. When the bass ascends, pressure decreases, the volume of gas in the bladder expands, and buoyancy increases. Bass can remove gas from the bladder with the gas gland, but this is a relatively slow process. Therefore, a bass quickly displaced from deep water to shallow water (de-pressurized) is helplessly buoyant and suffers physical damage ("the bends"). Until gas volume is reduced, the fish is unable to return to deep water and relieve the physical problems caused by de pressurization.

Anglers catching bass from water deeper than 30 feet must be aware of this potential problem. Symptoms of rapidly de-pressurized fish include air bubbles in the eyes and fins, bloody fins due to ruptured blood vessels, and protruding eyes (appear "bug eyed"). In extreme cases, bass with overinflated gas bladders will have their stomachs forced into their mouths. Behavioral symptoms of bass with buoyancy problems include fish that remain at the surface after release and bass that lie on their side or assume a "head-down" posture in the live well.

When bass show symptoms of de-pressurization, it is necessary to relieve the excess gas from the bladder to allow the fish to descend or to return the fish to deep water to minimize further physical damage. Completely evaluated techniques for reducing the effects of rapid de pressurization have not been developed. Lowering the fish to the depth at which it was caught (for example, see article by Mannas 1986) may be effective if the fish can be released immediately. A method suggested by the California Department of Fish and Game Warm water Fishery Board (1987) involves puncturing the gas bladder with a hollow needle (such as used with a hypodermic syringe). If you attempt this procedure, use a 16to 20 gauge needle under a scale, through the skin,, and into the body cavity to puncture the gas bladder. The location of insertion is important, because sticking a vital organ, such as the closely-located kidney, can kill the fish. To locate the point of insertion, draw an imaginary line form the notch separating the spiny-ray and soft-ray portions of the dorsal fin downward to the anal opening. Insert the needle along this line approximately midway between the lateral line and the anal opening (3-5 scale rows below the lateral line). If properly inserted into an overinflated bladder, air can be felt coming out of the end of the syringe needle. Dissection and examination of dead fish can be helpful in determining the best location for insertion of the needle. If the stomach has been pushed into the mouth by the overinflated gas bladder, push the stomach back through the throat of the fish with a blunt object after the air has been released from the gas bladder. Because de-pressurization can cause significant internal damage to the fish, treatment for gas bladder over inflation should be done as soon as buoyancy problems are evident.

Releasing Fish

Live fish should be released into good quality water. Observations of bass released after tournaments indicate strong, non-stressed bass may move several miles to desirable habitats. On the other hand, stressed bass may move to the nearest cover or simply rest on the bottom at the release site. To insure that stressed bass may move to the nearest cover or simply rest on the bottom at the release site. To insure that stressed fish have the best possible environmental conditions for recovery and survival, they should be released at a location where they have access to well-oxygenated, relatively cool, clean, and deep water.