Effects of depth in semi-controlled artificial incubation on egg hatching success of Crocodylus acutus (Cuvier, 1807) and hatchlings biometry

Abstract

Semi-controlled artificial incubation methods of crocodile eggs use low technology devices where one or more parameters cannot be controlled, but with the advantage that they are less expensive and logistically more feasible. This study evaluated the effect of different artificial incubation depths on the hatching success of eggs of Crocodylus acutus, under semi-controlled conditions, and analyzed biometric data of the hatchlings. The crocodile nests were collected from sandbanks of the two rivers (Río Negro and Río Santa Rosa), both located at Machiques de Perijá, Zulia state, Venezuela. The results showed a significant and positive effect on hatching success when the eggs were buried at 2 cm depth, compared to those at 10 cm and 20 cm. The hatching success at 2 cm depth was 82.43%. Also, we found that the size and weight of the hatchlings, as well as the relationships between these biometric variables, depend on the place of origin of the nests. The highest hatching percentage obtained at 2 cm was probably due to the effect of optimal incubation temperatures at this depth. The isolation and controlled heating system of the incubation room would prevent extreme fluctuations in temperature, favoring greater hatching at 2 cm depth. Differences in the biometric aspects of the hatchlings could be associated with differences in the size and the physiological status of the females from both sites.