Incubation temperatures, sex ratio and hatching success of leatherback turtles (Dermochelys coriacea) in two protected hatcheries on the central Mexican coast of the Eastern Tropical Pacific Ocean

J García–Grajales,J F Meraz Hernando,J L Arcos García,E Ramírez Fuentes

doi:10.32800/abc.2019.42.0143

Abstract

espanolLas temperaturas de incubacion, la proporcion de sexos y el exito de eclosion de la tortuga laud han recibido poca atencion en los programas de conservacion en Mexico. Este estudio se realizo entre octubre de 2014 y mayo de 2017 en dos criaderos cercados. Para determinar los parametros de temperatura en el ambiente de la camara de anidacion y su variacion durante el periodo de incubacion, colocamos registradores de datos en el centro de cada nido trasladado. Posteriormente, se enterraron otros registradores en la arena cerca de los nidos trasladados, dentro y fuera del criadero. Se analizo un total de 46 nidos durante tres temporadas de anidacion. No se observaron diferencias estadisticas en la temperatura media entre los nidos del criadero de San Juan Chacahua ni entre los de Palmarito. La proporcion de sexos basada en la temperatura media durante el segundo tercio del periodo de incubacion fue del 96,3% en favor de la produccion de hembras. El exito de eclosion en los criaderos de San Juan Chacahua y de Palmarito fue alto. Nuestros resultados concuerdan con el patron habitual de proporcion de sexos observado para la tortuga laud, que esta dominado por la presencia de hembras. Ademas, los indices de exito de eclosion en el criadero protegido con sombra artificial fueron mas altos que los observados en los nidos naturales en otras poblaciones. EnglishIncubation temperatures, sex ratio and hatching success of leatherback turtles have received little attention in conservation programs in Mexico. This study was carried out from October 2014 to May 2017 in two enclosed hatchery sites. To determine temperature parameters in the nest chamber environment and their variation during the incubation period, we placed data loggers in the centre of the egg mass in relocated nests. We then buried other data loggers in the sand near the relocated nests, inside and outside the hatchery. A total of 46 nests were examined over three nesting seasons. Mean nest temperature showed no statistical difference between nests in either the San Juan Chacahua hatchery or in the Palmarito hatchery nests. The mean sex ratio based on average temperature during the middle third of incubation duration was 96.3% skewed to female production. Hatching success in both San Juan Chacahua and Palmarito was high. Our findings support the common pattern of a female–dominated leatherback turtle sex ratio. Furthermore, hatching success rates in the shade–cloth hatchery were higher than those in the natural nests observed in other populations.

Highlights

The leatherback turtle (Dermochelys coriacea) inhabits a wide range of coastal and pelagic waters in tropical and temperate ecosystems
A total of 46 nests were examined for nest temperatures during three nesting seasons in the two hatcheries from the Central Pacific Coast of Oaxaca
The nest temperatures recorded inside the chamber nests were near the upper tolerance limits for incubation of leatherback turtle eggs and the results of the present study were in agreement with the common pattern of leatherback turtle hatchling sex ratios from beaches in the Eastern Pacific, which is female–dominated

Summary

Introduction

The leatherback turtle (Dermochelys coriacea) inhabits a wide range of coastal and pelagic waters in tropical and temperate ecosystems They are found in both hemispheres, from the equator to sub–polar regions, nesting activity is confined to tropical and subtropical latitudes (Benson et al, 2015). Secondary beaches where turtles nest regularly can be considered important nesting sites (Santidrían et al, 2017) In all of these beaches, nests are protected by relocating freshly laid clutches to protected hatcheries —a common practice used at sea turtle rookeries around the world— to increase hatchling recruitment (Baskale and Kaska, 2005; Maulany et al, 2012; Santidrían et al, 2017). In this context and knowing that temperature plays an important role in the life–history of sea turtles (Binckley and Spotila, 2015), it is important to understand temperature regimes in enclosed, protected hatcheries and corresponding hatchling sex ratios and hatching success because few detailed studies have been conducted on these topics and on the effectiveness of hatchery management on leatherback turtle nests laid on secondary beaches in the Mexican Pacific (Vannini and Rosales, 2009; Vannini et al, 2011)

Objectives

Methods

Results

Discussion

Conclusion