Capture of farmed Nile crocodiles (Crocodylus niloticus) : comparison of physiological parameters after manual capture and after capture with electrical stunning

Abstract

The electric stunner (e-stunner) is commonly used to handle Nile crocodiles (Crocodylus niloticus) on commercial farms in South Africa, but while it seems to improve handling and safety for the keepers, no information regarding physiological reactions to e-stunning is currently available. The aim of this study was therefore to compare various physiological parameters in farmed Nile crocodiles captured either manually (noosing) or by using an e-stunner. A total of 45 crocodiles were captured at a South African farm by either e-stunning or noosing, and blood samples were taken immediately as well as four hours after capture. Parameters monitored were serum corticosterone, lactate, glucose, as well as alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, and creatinine kinase. Lactate concentrations were significantly higher in noosed compared to e-stunned animals (P < 0.001). No other blood parameter differed significantly between the two capture methods. In addition, recorded capture time confirmed that noosing takes significantly longer compared to e-stunning (P < 0.001), overall indicating that e-stunning seems the better option for restraint of especially large numbers of crocodiles in a commercial setup because it is quicker, safer, and did not cause a significant increase in any of the parameters measured.