Do live-well additives influence the physiological and behavioral recovery of Largemouth Bass?

Objective: There is an ongoing effort to enhance the welfare and survival of black bass Micropterus spp. released after angling tournaments. Live-well additives are substances added to live-well water that are intended to help fish recover during retention. Aside from claims made by manufacturers, little information is available on the additives' effectiveness for recovery or their potential welfare consequences. Thus, our objective was to test whether live-well additives influence fish physiology and postrelease behavior. Methods: Two techniques were used to test the influence of live-well additives on the welfare of angled Largemouth Bass M. nigricans (LMB) held in a live well with lake water (control) or one of three additive products. Prior to fish release, pop-off biologging packages were fastened to a subset of LMB to monitor behavior (locomotor activity, depth, and water temperature use) for 5 min (n = 61) and blood samples were taken from another subset of LMB to assess their physiology (n = 47). We obtained baseline (n = 9) blood samples from LMB immediately upon capture. Result: Regardless of treatment, postrelease locomotor activity increased with increasing time spent in the live wells. Live-well additive type alone did not have an influence on the postrelease locomotor activity. Further, LMB retained in the live wells had greater blood glucose and lactate concentrations relative to baseline LMB, suggesting that fish did not recover from angling during retention in live wells. Other than elevated plasma chloride levels of LMB held in one of the live-well additives, plasma chloride and sodium concentrations for LMB in live wells with additives and for those in the control live well did not differ, suggesting that the LMB had not recovered while retained. Conclusion: Our results suggest that the live-well additives tested did not enhance recovery or reduce confinement stress of LMB retained in live wells under the tested circumstances. Additional research on live-well additives is needed given that our findings did not align with the claims made by the manufacturers of these products. We suggest that anglers intending to retain fish in live wells should use fresh, well-oxygenated lake water.