“A few years ago, we conducted a study that showed that angling time can be a critical issue for nesting bass caught in spring. We found that male bass landed in just 20 seconds quickly returned to their nests. Exhausted bass (fought for 2 minutes or more) took much longer to resume guarding the bed. Moreover, nests of the exhausted bass experienced much higher levels of predation.”

Ego Kills

It’s ironic that many anglers practice catch and release, but only do it properly with bass that easily can shake off the effects of the event—the little ones. They’re released without fanfare. But when they catch a big bass, out comes the net, then long admiring glances, photos, and perhaps a ride in the livewell.

“From a conservation standpoint, big fish are extremely valuable. They’re the best spawners and the ones we should be releasing. Unfortunately, big bass are most damaged by catch and release. They’re battled longer and held out of water longer. This contributes to a greater physiological disturbance.

“We’ve found that the buildup of lactic acid in the muscles of big fish can be almost twice that found in smaller individuals following the same amount of burst exercise. Although much of the research in this area has been conducted on trout and salmon, similar physiological changes could affect big bass, muskies, and walleyes.”

Deadly Effects Of Warm Water

Water temperature also affects the physiological disturbance of fish. Tufts notes that most anglers know that warm water can make catching fish more difficult, but they fail to realize the effects of warm water on fish after they’re hooked.

“Water temperature increases the severity of the physiological disturbance in the blood of a caught fish,” Tufts says. “In species most sensitive to temperature increases, the ability to tolerate angling, handling, and confinement in livewells declines markedly as water warms.

“When water temperatures rise in summer, fish are more fragile and become more susceptible to delayed mortality following catch and release. Holding fish in livewells under these conditions exacerbates the problem. In extremely warm water, anglers should be careful not to fight fish to exhaustion. And they should release fish immediately.”

Help . . . I Can’t Breath

Needlessly exposing fish to air is the final factor that anglers need to consider, and it’s one over which they have full control. Many of the physiological responses initiated in a fish when you hook it are designed to facilitate the transport of oxygen.

“When you remove a fish from the water, however, the delicate secondary lamellae in the gills collapse, inhibiting gas exchange. This can be serious in a fish fought to near exhaustion.”

Consider the consequences of holding your own breath under different conditions. When you’re resting, it’s not a problem to stick your head under water and hold your breath for a short time. It’s another story, however, after you just ran a 100-yard dash. From a bass’ point of view, the consequences of hindering gas exchange after exercise can be devastating. The longer you hold the fish out of water the greater the physiological disturbance.

Experts agree that fish handling is one important hurdle we must pass to ensure healthy fisheries in the future. The old adage says that you must think like fish in order to catch them. Another angle is that to safely release fish, you must understand the basics of their physiology. n

*Dr. Bruce Tufts is Professor of Biology at Queen’s University, Kingston, Ontario. He has worked on the physiology of catch and release since the late 1980s and has published many scientific papers on this topic.

In-Fisherman Field Editor Gord Pyzer has a Masters degree in Resource Management. He was a senior manager with the Ontario Ministry of Natural Resources for almost 30 years.