Evaluation of nest management phases for Lepidochelys olivacea at two beaches in Northwest Mexico.

Abstract

The olive ridley turtle, Lepidochelys olivacea, is a vulnerable and endangered species according to the IUCN and Mexican Official Standard NOM-059, respectively. On most solitary nesting beaches of olive ridley turtles, the eggs are removed from the in situ nest to hatcheries due to the high incidence of predation, human poaching, and beach erosion; therefore, it is necessary to collect and analyze information on the protection activities conducted for this species from egg laying to hatchling release. In general, protection activities during nest management can be divided into 5 phases: nest logging (F1), egg collection (F2), egg transfer (F3), egg incubation and hatching (F4), and hatchling release (F5). This work was carried out on two Pacific beaches in northwestern Mexico, Ceuta Beach Sanctuary (CBS) during 2013-2019 and Caimanero Beach (CB) during the 2013-2018 nesting seasons, with the objective of quantitatively evaluating the management phases of the protection program for olive ridley turtles by assessing the nest, egg, and hatchling losses in each of the phases using the model of Godínez-Domínguez et al. (1991). The results of the statistical analyses indicate that the greatest losses occurred during the incubation phase (F4) at both beaches, with a 41.99% loss at CBS and a 33.09% loss at CB, followed by the F2 (with 15.56 and 27.27% losses, respectively) and F1 (21.28 and 25.56% losses, respectively) phases. Significant differences between the beaches were observed in F4, F5 and F3, with greater losses at CBS than at CB, indicating that the success of the management phases may vary among beaches. The results obtained show that it is necessary to focus on strategies for improving the success of mainly phase F4 and phases F1 and F2 at both beaches.