CARDIOVASCULAR, VENTILATORY AND TOTAL ACTIVITY RESPONSES OF BROWN TROUT TO HANDLING STRESS

Changes in total activity, heart and ventilation rates were observed i n 2-year-old brown trout, following handling stress, using non-contact bioelectronic monitoring equipment. Experiments were carried out in l aboratory conditions at water temperatures below 4 degrees C. Transfer between tanks as well as 5 min restraint stress increased the total a ctivity of fish for 24 to 48 h, after which it declined to near the pr e-stress lever. The transfer and struggle both elevated the heart rate for 3 to 4 days. Ventilation rate was elevated to a maximum of about 30% above the nominal level and recovered within 3 to 4 days. Both hea rt and ventilation rates were higher in feeding fish relative to fasti ng fish after stress and rates remained higher throughout a 7 day peri od of recovery. A diel rhythm of lower rates during the night appeared in both heart and ventilation rates within 3 to 4 days after handling stress.