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 C niloticus 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 creatine kinase. Lactate concentrations were significantly higher in noosed compared with e-stunned animals (P<0.001). No other blood parameter differed significantly between the two methods of capture. In addition, recorded capture time confirmed that noosing takes significantly longer time compared with e-stunning (P<0.001), overall indicating that e-stunning seems to be 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.

Venous hematology, biochemistry, and blood gas analysis of free-ranging Eastern Copperheads (Agkistrodon contortrix) and Eastern Ratsnakes (Pantherophis alleghaniensis)

“…Temperature corrections did not affect statistical comparisons between copperheads and ratsnakes. Despite all of the snakes in this study appearing outwardly healthy on physical examination, lactate concentrations both at the beginning and end of restraint were higher than the reported lactate concentrations from other reptiles, except cold-stunned Kemp's ridley sea turtles on their first day of rehabilitation and manually restrained Nile crocodiles [5,43,[47][48][49][50][51][52][53]. The higher lactate concentrations in copperhead and ratsnakes may reflect species-specific differences in anaerobic metabolism or differences in instrumentation, however, additional considerations for elevated lactate in reptiles include hepatocellular damage, renal disease, hypoventilation, poor perfusion, and cardiovascular disease [12,54].…”

Reference levels for corticosterone and immune function in farmed saltwater crocodiles (Crocodylus porosus) hatchlings using current Code of Practice guidelines

“…As such, CORT has been used to assess various aspects of captive crocodilian propagation such as stocking densities (Elsey et al, 1990a(Elsey et al, , 1990b, water temperature (Turton et al, 1997), capture method (Franklin et al, 2003;Pfitzer et al, 2014), pen type and reproductive output (Elsey et al, 1990a(Elsey et al, , 1991Lance and Elsey, 1986). Using this information, Codes of Practice for the captive propagation of crocodilians have been established (CFAZ, 2012;LDWF and LSU, 2011;NRMMC, 2009;SABS Standards Division, 2014).…”

Evidence of Infection with Zoonotic Mosquito-Borne Flaviviruses in Saltwater Crocodiles (Crocodylus porosus) in Northern Australia

“…None of the sampled crocodiles had a history of clinical diseases. During harvest, crocodiles were captured using an electrical stunner that temporarily rendered the crocodile immobile and unconscious, in order to allow for safe handling, as previously described [ 34 , 35 ]. After immobilisation, blood was aseptically collected from the occipital sinus using 18” needles and plain (without anticoagulant) vacutainer tubes (Becton Dickinson, Franklin Lakes, NJ, USA).…”