Determining sex ratios of turtle hatchlings

Metadata Updated: March 7, 2016

Previous status assessments of marine turtles have assumed that the natural sex ratio of a marine turtle population is 1:1 (e.g. Conant et al. 2009). However, this is largely speculative and is based on few data, a troubling fact considering the importance of sex ratios when modeling the status of marine turtle populations. Marine turtles exhibit temperature sex determination (TSD), such that the overall sex ratio of hatchlings produced on a nesting beach is affected by the incubation temperatures on that beach (Mrosovsky and Yntema 1980, Rimblot et al. 1985). This creates unique susceptibility of marine turtles to global climate change and deforestation at nesting beaches (Hawkes et al. 2007). And although research has shown that the temperature threshold may vary among species and beaches, there are relatively few studies on hatchling sex ratios (Chevalier et al. 1999, Wibbels 2003, Mrosovsky et al. 2009). Considering the extreme importance of knowing sex ratio when modeling population abundance and trends, it is essential to conduct studies to determine sex ratio at various nesting beaches. In this study, we proposed to monitor thermal environments at the St. Croix, USVI, leatherback turtle nesting beach and the Bahia de Jiquilisco-Xiriualtique Biosphere Reserve in El Salvador for hawksbill turtles.

During the nesting season in 2012, temperature loggers (HOBO U22) were deployed in 42 nests (20 relocated and 22 in situ nests, of which 39 were retrieved). Temperature loggers (n = 55) also were placed on the beach at 50 cm from the surface, corresponding to the approximate depth of a next. Of the 55 loggers, 23 were retrieved but 32 were lost due to unexpected beach erosion during this season. Eighty eight nests have been excavated and naturally deceased hatchlings and unhatched embryos (n = 487) collected. This sample size was approximately five times more than expected. Gonad samples are preserved in formalin and were shipped to Florida Atlantic University at the end of the season for anatomical and histological examinations. As of late April 2013, 101 samples have been histologically examined. Of these 101 samples, the sex of 12 could not be determined because of advanced decomposition. For the remainder, 11 (12%) were male and 78 (88%) were female, indicating female-skewed sex ratio at this nesting beach. Histological examinations are underway to determine the remainder of the samples. Although the thermal profile of the nesting beach for this year has not been created, a similar project was conducted in the previous years by a graduate student (Emily Weston) of Jeanette Wyneken (TE is a committee member).

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Metadata Date 2016-02-27T06:37:09.681-05:00
Metadata Created Date September 26, 2015
Metadata Updated Date March 7, 2016
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Resource Type Dataset
Metadata Date 2016-02-27T06:37:09.681-05:00
Metadata Created Date September 26, 2015
Metadata Updated Date March 7, 2016
Reference Date(s) (publication)
Responsible Party Southwest Fisheries Science Center (Point of Contact)
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Access Constraints Access Constraints: None | Use Constraints: Disclaimer - While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
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Frequency Of Update
Guid gov.noaa.nmfs.inport:12736
Harvest Object Id 7d7448dc-524c-4f87-9858-8c4e53aaa1c5
Harvest Source Id 2aed8e29-fc5b-4cde-aa66-fb1118fd705e
Harvest Source Title NOAA CSW Harvest Source
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Metadata Language eng
Metadata Type geospatial
Progress onGoing
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True
Temporal Extent Begin 2012-04

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