Evaluation of 2 methods of ex situ incubation for sea turtle eggs in terms of nest temperature, hatching success, and hatchling quality

Abstract

At the marine turtle conservation program in Boca de Tomates, Jalisco, Mexico, all nests are relocated to fenced-off beach hatchery or polystyrene boxes due to illegal egg collection, predation, erosion, and high sand temperatures. For both methods we evaluated the following nest viability and hatchling quality parameters: hatching success, nest temperatures, incubation duration, and hatchling quality (locomotor performance, morphometrics, weight, and congenital malformations). Hatching success was significantly higher in the beach hatchery (mean 77.4%, n = 1,368) than in boxes (average 59.91%, n = 1,160) (P < 0.001). The beach hatchery nests hatched in less time (hatchery = 46 d, boxes = 51 d) (P < 0.001) due to the significantly higher mean temperature (hatchery = 32.62 ºC, boxes 30.58 ºC) (P < 0.001). The hatchery was exposed to less temperature variability per day (hatchery = 1.46 ºC, boxes = 2.69 ºC) (P < 0.001). To test hatchling quality, 10 hatchlings were randomly selected from each nest (n = 254). The weight, size, and locomotor performance (righting response and time to crawl 3 m) of these organisms were recorded. Live and dead neonates were carefully inspected for malformations (n = 2,000). No significant difference was found between incubation methods in any hatchling quality parameter (P > 0.050). The malformations at this site have low prevalence (hatchery = 1.35%, boxes = 1.89%) and low intensity index per organism (hatchery = 1.52, boxes = 1.89) compared to other studies and species. This is the first study, to our knowledge, that compares hatchling quality from 2 ex situ incubation methods in a single species (Lepidochelys olivacea), at the same location, and during the same period of time. Carrying out studies such as this one is important, since the quality of hatchlings can contribute to their ability to survive and reproduce in the future.