Livewell 101

You’re trapped in a hot, dark, stuffy fiberglass jail cell. Merely breathing is difficult, and you can barely move. Then the cell starts shaking and rolling violently, slamming you against the hard walls and floor. You’re bruised and battered, sweaty, and gasping for air when the ceiling is suddenly peeled back. Weak and nauseous, you feel yourself being yanked from the cell and plunged underwater. Desperately holding your breath, you see a monstrous needle quickly moving toward your head.

Now you know how a baitfish feels when you take it out of the livewell and get ready to bridle it to a hook. It’s no wonder that a large number of the baits we rig up die in a matter of minutes or fail to give us that high-energy tail wiggle that predators find so enticing. You want to catch more fish? Then start giving them better baits — by housing your live offerings in the ultimate livewell.

Go With the Flow
Livewells for offshore baits can be divided into two main types: tanks and tubes. Tanks are far more common, but tuna tubes are necessary for keeping large marlin baits like Spanish mackerel, false albacore and skipjacks. Whether you’re using tubes or tanks, the single most important factor affecting your bait’s health is water flow. If your flow is insufficient, your baits die from lack of oxygen. If it’s too strong, your baits die of exhaustion while fighting the artificial current. So, how much flow is the right amount? Unfortunately, there’s no cut and dried answer, because different types of baitfish do better with different amounts of water flow. High-speed fish that need a lot of oxygen — like tinker mackerel — need faster-moving water than fish like goggle-eyes.

The solution to keeping different species of baits alive and kicking is variable water flow. This can be accomplished with adjustable control valves, available from companies like Rule, ITT and Flow-Rite, which are installed in the plumbing that feeds water to your tanks and tubes. What about those adjustable flow inlets that you find mounted in some bait tanks? Forget about them — if your livewell has a single inlet point, it already can’t qualify as an ultimate livewell. Where the water enters a well can be just as important as how much enters it, because single inflows can fail to efficiently mix the water. As a result, low-oxygen “dead spots” can form. To prevent this problem, the best livewells sport multiple water inlets spaced from top to bottom.
   
Naturally, you can’t dial up an adjustable flow above the pump’s capacity. So the ultimate livewell needs to have more than enough power to get the job done. Just how much juice does it take? To find out, we spoke with a guy who’s devoted much of his life’s work to keeping fish alive in captivity, Dr. Daniel Benetti, director of aquaculture at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science.
   
“Of course it depends on the size of the tank, but in general, to keep fish in top condition, the water should turn over at a rate of around 1,000 times a day,” he says. “It’s not just a matter of oxygenation, but also of removing ammonia and waste, as well as creating an ideal current.”
   
That means a livewell pump should be able to move about 42 times the tank’s capacity, per hour. In the case of a 30-gallon livewell, a pump that pushes 1,260 gph or more will keep most baits in prime condition. For a 50-gallon tank, a pump with 2,100 gph or more would do the trick.
   
As far as water velocity goes, Dr. Benetti’s experience — which includes raising goggle-eyes from the time they were fry until the time they were used as live baits to catch the university’s brood stock of tuna — has shown that an ideal current will move at about the same distance as one body length of the fish in captivity per second. “You can use this as a general rule,” he says, “and that’s about the minimal flow we look for with most pelagic fishes. But more, of course, is merrier.”
   
When it comes to keeping 10-pound baitfish in tubes, moving water fast enough to cover one body length per second is quite a high rate of flow. Tunas breathe via ram ventilation (water is forced through their mouth and over their gills by their forward motion, as opposed to fish that can bring water over their gills by pumping their jaws), so in the wild, some tuna species need to maintain a speed of about 0.65 meters per second just to breathe. How does this speed translate into water flow? As a general rule of thumb, if you plan to keep skipjacks and bonito of this size in tip-top condition for more than a few minutes at a time, you’ll want to have a minimum of 1,000 gph blasting through each tube they’re swimming in — and 1,500 gph is better.