Forced Swimming Effects On Nesting Smallies

Maybe you heard your high school football coach say it. Anyone that’s spent some time at the health club has heard the trite saying: “No pain, no gain.” You have to make those muscles burn if you want to put more muscle on. They burn, then they hurt. And the next morning you can’t lift your coffee cup. Keep that in the back of your mind next time you play a big fish.

Fish have muscle and experience the effects similar to ours from exercise. When and how we play fish could have long-term consequences after release. Take smallmouth bass, for example.

Craig Springer

Since male smallmouths are the primary care givers to the young, the spawning process is protracted, maybe up to six weeks long considering nest building, courtship, incubation and then guarding the fry with hardly a recess.

Males on the nest will fiercely guard their space from any intruder and the vulnerability of spawning smallies to angling is well known. In fact, to prevent over-harvest of smallmouth bass fisheries, some states and provinces have special fishing regulations, such as a closed season or catch-and-release during the spawning and parental-care period.

But even catch-and-release angling may produce undesirable outcomes to smallmouth fisheries. Assessing this question, researchers at Queen’s University in Ontario, Canada, performed a study designed to gauge the physiological effects of catch-and-release angling on nesting smallmouth bass.

Catching Nest-Guarding Smallies
Nest-guarding smallmouths were caught by hook and line and played either less than 20 seconds or to complete exhaustion. Next, the scientists measured in the fish, the depletion of a chemical used for energy, adenosine triphosphate (ATP), and the accumulation of lactate, the chemical responsible for sore muscles after exercise. Concentrations of ATP and lactate were compared to the length of time that fish were played. Two other parameters studied were the amount of predation on their young while absent from the nest and the time elapsed before individuals returned to nest guarding after release.

Smallmouth bass played to exhaustion had about 50 percent of their ATP reserves depleted. The resultant lack of energy corresponded to higher levels of lactate. Smallmouth quickly landed had an eight-fold increase in lactate compared to a 13-fold increase in fish played to exhaustion.

Fighting nesting smallmouth bass to exhaustion is very detrimental to the health of the fish and the offspring it is trying to protect from predation.

Catching and releasing males off the nest obviously disrupts parental activities. But what impact might it have on offspring? A lack of protection from a parent leaves young fish, or eggs, vulnerable to predation. It took exhausted fish an average of eight minutes to return to nest guarding. Those landed quickly returned in just two and a half minutes. Thirty-five percent of nests of those fish played less than 20 seconds were preyed upon while the guarding males were absent. Half the nests of the exhausted fish experienced incidents of predation. The total time predators took liberty in unguarded nests was 13-times higher in the nests where fish were played to exhaustion.

While each smallmouth bass fishery is unique in terms of population dynamics, suffice it to say that even catch-and-release fishing at this particularly vulnerable time will have detrimental effects on smallmouth populations.

Maybe we should all give a wide berth the next time we see that ring of bare cobbles in the shallows this spring? In the end, the fishing may be better for it.

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When not penning stories about the outdoors, Craig works in communications for the U.S. Fish and Wildlife Service. He is an outdoors’ columnist for the Albuquerque Journal and ESPN Outdoors, and a frequent contributor to Flyfisher and North American Fisherman magazines. He holds degrees in fisheries and wildlife management from Hocking College and New Mexico State University, and an M.Sc. in fisheries science from the University of New Mexico. He’s a candidate for an M.A. in rhetoric and writing at the University of New Mexico. He writes weekly for

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