Without oxygen, life ends. Just ask the minnows panting in your bucket or those belly-up bass in the harbor after a tournament. Our own need for oxygen is painfully evident if we go without it for even a minute. Since fish extract oxygen from water, though, it's hard for us to appreciate how much oxygen they need.

THE SCIENCE
Gene Gilliland, a fishery biologist with the Oklahoma Department of Wildlife Conservation, has conducted studies of bass tournament mortality for over a decade. He's worked with angler groups to determine causes of mortality and to teach methods to increase survival of released fish.

"I checked oxygen levels of tournament boats as they returned to the dock," Gilliland says. "Many livewells had less than 4 parts per million dissolved oxygen. Though most bass were alive, high stress levels caused excessive delayed mortality in the days after the competition. I then questioned anglers on their use of salt, livewell additives, ice, and the operation of their aeration systems.

"Most anglers mistakenly believed that running their aerators on the automatic timer was sufficient for as many bass as they could catch," he says. "They often told me that they didn't know how much air bass needed. Obviously, livewell design, size, and efficiency varies. Human variables and weather conditions, particularly water temperature, affect water quality and fish mortality. If the lake is over 75 degrees, it's impossible to keep the dissolved oxygen level in your livewell much over 5 or 6 ppm, even with no fish in it."

When you consider that levels below 5 ppm are stressful and that walleyes require nearly three times as much oxygen as bass, it becomes evident why fish are so hard to keep alive with standard equipment. Part of the problem with aeration is that air is only 21 percent oxygen. Fish need oxygen, not the extra nitrogen and trace gases that make up our atmosphere. The answer is injecting pure oxygen into livewells or bait tanks.

David Kinser of Anahuac, Texas, has developed oxygenation systems for tournament boats, boat baitwells, and dockside bait tanks. His systems supercharge water with oxygen, boosting dissolved oxygen over 20 ppm, even in water over 80 degrees. These systems are popular with freshwater and saltwater anglers.

Kingfish and striper tournament boats are increasingly equipped with oxygenation systems. Not only don't baitfish die, but they're unusually more active on the hook and they draw more strikes. Short-term oxygen supersaturation hasn't been shown to harm fish, as some observers had feared. Instead, it seems to suppress the stress response that occurs in captive fish.

Gene Gilliland and other researchers have tested the system in bass tournament conditions in Oklahoma and have found it capable of reducing mortality in summer to below 10 percent; continuous aeration resulted in mortality over 20 percent; and the use of ice and salt resulted in 18 percent mortality. Gilliland says, "Adding oxygen to the livewell is the best option for keeping bass healthy in summer."

THE SYSTEM
Oxygenation systems involve a cylinder of medical or welding-grade oxygen and flow regulators to maintain adequate oxygen levels. Tubing and finely porous airstones or micro-pore tubing provide flow into the livewell or bait tank. The cost of an oxygen system ranges from about $350 for a boat unit to $600 or more for a larger bait tank unit.

Once installed, cost of running pure oxygen is just a couple cents per hour, as the small onboard tank will provide supersaturated oxygen for several days and can be refilled from a larger tank at home, or at a welding shop, fire station, or hospital. Kinser also has built systems that release pure oxygen into lakes during summer stratification, attracting large schools of baitfish and predators to the oxygen-saturated water.

Pure oxygen demands caution. While it doesn't burn, oxygen does intensify fire. As a result, onboard tanks should be mounted securely and away from sources of fuel or vapors such as the bilge. Gilliland mounted his tank in the small compartment under the driver's seat, running the tube rearward into the livewell of his Champion boat. For more information about Kinser's oxygenation system, contact David Kinser, Oxygenation Systems of Texas, PO Box 383, Anahuac, TX 77514, 409/267-6458, www.oxyedge-chum.com.

Despite air temperatures over 100 degrees, delayed mortality during tests when oxygen was added to livewells averaged only 7 percent, compared to 32 percent with intermittent aeration. Survival rages are much higher during tournaments held in cool weather.