Stress and hematological responses of juvenile silver carp (Hypophthalmicthys molitrix) to handling caused by capturing

Document Type : Research Paper



Due to the superior role of silver carp (Hypophthalmichthys molitrix) in the carp polyculture system, this study was conducted to evaluate the effects of catching, handling and transportation on hematological and biochemical parameters of juvenile fish (13.5±1.5g). Hematological and biochemical parameters were measured before catching (without handling), during the catches and 1, 3, 6, 12, 24 and 48 hours after transportation. The biochemical parameters including cortisol, glucose and lactate had significant differences among treated fishes (P<0.05). The cortisol and glucose levels rose quickly since catching up to 12 hours after it and significantly decreased after 24 hours, but it never returned to the normal level. The highest and lowest level of lactate was observed during catches and coming 12 hours. Except monocytes, all hematological parameters including the number of white and red blood cells, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, neutrophils and lymphocytes had significant differences among treated fishes (P<0.05). The amounts of hemoglobin and hematocrit were significantly increased 12 hours after fishes were caught (P<0.05). The results of hematological and biochemical parameters showed that catching and handling of juvenile silver carp had harassment effects on fish welfare and it is necessary to provide optimum conditions to reduce stress effects.