TRIPLOIDY DECREASES THE AEROBIC SWIMMING CAPACITY OF RAINBOW-TROUT (SALMO-GAIRDNERI)

1. 1. Two-summer-old diploid and triploid rainbow trout from an all-female stock were forced to swim for 3 hr at 40 cm/s. At the end of the test the fish were sampled for biochemical analyses. Respective samples were taken from resting controls. 2. 2. Blood haematocrit (Hct) and haemoglobin concentration (Hb), mean corpuscular haemoglobin concentration (MCHC), erythrocytic water content, plasma glucose and lactate concentrations, liver glycogen content, plasma Cl-, Na+, K+, Mg2+ concentration and plasma concentrations of insulin, glucagon and glucagon-like peptide (GLP) were measured. 3. 3. In the triploid trout, the blood Hct value and plasma lactate concentration increased and MCHC decreased in exercise, indicating swelling of the erythrocytes and accumulation of anaerobic metabolites; these changes were less pronounced or not present in the diploid fish, which indicates that triploid trout have a lower aerobic capacity than the diploid ones. 4. 4. Plasma insulin concentration decreased in exercise both in the diploid and triploid fish, but the decrease was more pronounced in the triploids. Plasma glucagon and GLP concentrations of the diploids decreased (GLP not significantly), but those of the triploids increased in exercise. © 1990.