THE EFFECTS OF COMMON LABORATORY AND HUSBANDRY PRACTICES ON THE STRESS-RESPONSE OF GREENBACK FLOUNDER RHOMBOSOLEA-TAPIRINA (GUNTHER, 1862)

This study examined the stress response of the greenback flounder Rhom bosolea tapirina to common laboratory and aquaculture practices. Plasm a levels of cortisol in wild fish sampled within 2 min of capture were comparable to plasma cortisol values in other species captured from t he wild and sampled immediately. Plasma levels of cortisol were signif icantly higher in wild fish sampled after capture, confinement and tra nsport. The latency of the plasma cortisol response to stress was appr oximately 10 min. Cultured greenback flounder, exposed to normal husba ndry conditions, had low plasma cortisol levels; however, 3 h of crowd ing combined with 5 min chasing (simulated grading) resulted in signif icantly elevated cortisol levels for;up to 48 h. Plasma cortisol was s ignificantly higher in fish held at medium and high stocking density t han at low density. The plasma cortisol stress response of greenback f lounder is similar to that shown by other marine teleosts. Plasma lact ate levels in wild fish sampled after capture, confinement and transpo rt, were considerably higher than levels in fish sampled within 3 min of capture, or exposed to 30-min exercise. No significant changes in m uscle lactate were observed in response to exercise; however, there we re significant increases in plasma lactate, and muscle [H+] and a sign ificant decrease in plasma [H+] following exercise, indicating that mu scle;and blood physiology of greenback flounder do change in response to exercise. Unlike other flatfish, there was little evidence for in s itu glycogenesis within white muscle tissue after exercise and there w as some indication that greenback flounder have higher aerobic scope t han other flatfish studied to date. This study showed that some routin e husbandry practices have the capacity tl, stress greenback flounder. (C) 1998 Elsevier Science B.V. All rights reserved.