Assessment of hatchery management for the loggerhead turtle (Caretta caretta) nests on Göksu Delta, Turkey

Abstract

Sea turtles suffer from numerous threats such as predation, tidal inundation, and coastal building. We aimed to assess the effectiveness of hatchery technique on Göksu Delta beach, Turkey during the nesting season of 2010. For this purpose, eggs of loggerhead turtle (Caretta caretta) nests under the risk of tidal inundation were transferred into two protected hatchery sites that were constructed on Göksu Delta beach, in which there were no risk of predation and inundation, and the other nests were left to remain in situ. Hatching success of hatchery and natural nests were calculated. In addition, temperatures of both hatchery and natural nests (5 and 6 nests, respectively) were recorded, and sex ratios were determined using these nest temperatures and incubation periods. It was determined that hatching success increased with increasing distance from the sea (until 31 m) (r2 = 0.98), increasing incubation period (up to 60 days) (r2 = 0.68), and decreasing clutch size (r2 = 0.93), implying that the production of male hatchling is high in a nest if hatching success of that nest is high (or vice versa). Mean hatching success, incubation period, and nest temperature for hatchery nests were found to be 72.8%, 51.1 days, and 30.2 °C, respectively, while the corresponding values for natural nests were found to be 40.5%, 49.9 days, and 31.1 °C, respectively. It was also detected that hatchery nests produced higher proportion of male hatchlings (25.2%) compared with natural nests (13.5%). Based on all these results, it can be concluded that hatchery management on this beach is not a completely effective conservation technique. Nest relocation and/or hatchery management enable the conservationists to increase hatching success rate, but they cause sex ratio alteration. In this respect, we can only partially support nest relocation and/or hatchery management. They should be considered as a last option due to sex ratio alteration. © 2017 Elsevier Ltd