"When and how we play fish could have long-term consequences after release."
Researchers at Queen's University in Ontario, Canada, performed a study to gauage the physiological effects of catch and release on nesting smallmouth bass. This article may be found at http://www.smallmouth.org/NationalConservation.html in relation to the The Smallmouth Alliance and Smallmouth Conservation news.
This article states 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. Concentration of ATP and lactate were compared to the length of time that fish weere 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% of their ATP reserves depleted. The resultant lack of energy corresponded to higher levels of lactate. Smallmouth quickly landed had an 8-fold increase in lactate compared to a 13-fold increase in fish played to exhaustion.
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 populations dynamics, even catch-and-release at this particularly vulnerable time of year will have detrimental effects on smallmouth populations. Maybe we should give a wide berth the next time we see that ring of bare cobbles in the shallows in the springtime.
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