Kemp's Ridley Sea Turtle Saga and Setback: Novel Analyses of Cumulative Hatchlings Released and Time-Lagged Annual Nests in Tamaulipas, Mexico

Caillouet, Charles W.; Gallaway, Benny J.; Putman, Nathan F.

doi:10.2744/ccb-1189.1

Cited by 14 publications

(27 citation statements)

References 228 publications

(285 reference statements)

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“…Disturbingly, Kemp's ridleys have failed to meet projected nesting numbers since 2010, and re covery of this species to historic numbers has slowed in recent years (Caillouet et al 2016). Future monitoring of nesting and other abundance measures may yield insight into possible population-level effects of the DWH spill, but limitations should be anticipated due to difficulty in disentangling spill effects from other anthropogenic and non-anthropogenic factors.…”

Section: Discussionmentioning

confidence: 99%

Density and exposure of surface-pelagic juvenile sea turtles to Deepwater Horizon oil

McDonald¹,

Schroeder²,

Stacy³

et al. 2017

Endang. Species. Res.

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The 2010 Deepwater Horizon (DWH) oil spill posed a severe threat to surface-pelagic sea turtles because the surface convergence zones, which provide vital habitat by aggregating pelagic Sargassum and other floating material, also aggregated floating oil. Following the DWH spill, turtle rescue operations between 17 May and 9 September 2010 documented 937 juvenile sea turtles in the spill area and examined 574 captured turtles. Of the captured turtles, 81% were visibly oiled. Transect searches in convergence zones found Kemp's ridleys (51% of individuals), green turtles (37%), loggerheads (7%), hawksbills (2%), and unidentified sea turtles (2%). Linetransect methods estimated the density of all surface-pelagic sea turtles in surface convergence zones to be 3.32 km −2 (95% CI = 2.82-3.88), and the density of heavily oiled turtles to be 0.24 km −2 (95% CI = 0.15-0.39). Turtle densities and the areal extent of heavy oiling probability were used to estimate total number of turtles exposed to DWH oil. We estimate approximately 402 000 surface-pelagic sea turtles were exposed, and of those, 54 800 were likely to have been heavily oiled. Our estimates formed the basis of surface-pelagic juvenile sea turtle mortality estimates included in the DWH natural resource damage assessment.

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Section: Discussionmentioning

confidence: 99%

Density and exposure of surface-pelagic juvenile sea turtles to Deepwater Horizon oil

McDonald¹,

Schroeder²,

Stacy³

et al. 2017

Endang. Species. Res.

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“…However, there is evidence that the Kemp’s ridley re-migration interval increased from 2008 to 2016 and was approximately 3.5 years in the time period 2014 to 2016 [46]. Changes in remigration intervals due to decreased foraging resources, density-dependent effects, and/or changes in environmental conditions have been proposed as possible factors underlying the recent reduction in Kemp’s ridley nest numbers [47]. Given relatively short reproductive longevity, delayed remigration could result in fewer nests overall during each female’s reproductive lifetime and a decrease in number of observed nests for the population.…”

Section: Discussionmentioning

confidence: 99%

“…Juvenile Kemp’s ridleys inhabit foraging areas both in the GOM and along the US Atlantic coast and questions have been raised regarding potential differences in somatic growth rates between the regions, as these have implications for differing ASMs and relative contributions to the reproductive population [13, 47, 50, 61]. Although some growth data have indicated that juvenile somatic growth rates in the GOM are higher, others suggest the converse is true [52].…”

Section: Discussionmentioning

confidence: 99%

“…The factors underlying decreased somatic growth for Kemp’s ridleys in the GOM are uncertain, yet there are a number of possibilities. Concurrent with extensive conservation efforts, from 1998 to 2010 the number of nests at the primary Kemp’s ridley nesting area increased exponentially, resulting in the release of hundreds of thousands of hatchlings each season [47]. Previous studies recognized that sufficient habitat and forage would be required to accommodate this influx of juveniles [54] and indicated that carrying capacity for the population might be reached at smaller sizes than in the past and that an abrupt “crash” might occur [10, 11].…”

Section: Discussionmentioning

confidence: 99%

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Variability in age and size at maturation, reproductive longevity, and long-term growth dynamics for Kemp's ridley sea turtles in the Gulf of Mexico

et al. 2017

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Effective management of protected sea turtle populations requires knowledge not only of mean values for demographic and life-history parameters, but also temporal and spatial trends, variability, and underlying causes. For endangered Kemp’s ridley sea turtles (Lepidochelys kempii), the need for baseline information of this type has been emphasized during attempts to understand causes underlying the recent truncation in the recovery trajectory for nesting females. To provide insight into variability in age and size at sexual maturation (ASM and SSM) and long-term growth patterns likely to influence population trends, we conducted skeletochronological analysis of humerus bones from 333 Kemp’s ridleys stranded throughout the Gulf of Mexico (GOM) from 1993 to 2010. Ranges of possible ASMs (6.8 to 21.8 yr) and SSMs (53.3 to 68.3 cm straightline carapace length (SCL)) estimated using the “rapprochement” skeletal growth mark associated with maturation were broad, supporting incorporation of a maturation schedule in Kemp’s ridley population models. Mean ASMs estimated from rapprochement and by fitting logistic, generalized additive mixed, and von Bertalanffy growth models to age and growth data ranged from 11 to 13 yr; confidence intervals for the logistic model predicted maturation of 95% of the population between 11.9 and 14.8 yr. Early juvenile somatic growth rates in the GOM were greater than those previously reported for the Atlantic, indicating potential for differences in maturation trajectories between regions. Finally, long-term, significant decreases in somatic growth response were found for both juveniles and adults, which could influence recruitment to the reproductive population and observed nesting population trends.

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“…The species recovered through a combination of domestic and international actions including establishing a bi-national working agreement between the U.S. and Mexico to increase the protection of nesting females, hatchlings, and eggs (Márquez Millan, Olmeda, Sánchez, & Díaz, 1989;Woody, 1989), prohibition of trawling in GoM waters offshore of Rancho Nuevo, the primary nesting beach in Mexico, during the nesting season (Márquez Millan et al, 1989), a reintroduction program, with a head-starting component, designed to form a secondary nesting colony at Padre Island National Seashore, Texas (Caillouet, Shaver, & Landry, 2015;Fletcher, 1989;, and gradual implementation of turtle excluder devices (TEDS) on U.S. shrimping vessels in the GoM (Turtle Expert Working Group [TEWG], 2000). Positive population growth was observed from the 1980s until 2010 (Caillouet, 2011;Crowder & Heppell, 2011;Gallaway et al, 2013), when annual nesting numbers dropped by 35.4% (Caillouet, Gallaway, & Putman, 2016). A decline in nesting numbers was evident in 2013 and 2014 (Caillouet, 2014;Caillouet et al, 2015), and the overall population was predicted to be decreasing by 5% per year (Heppell, 2014).…”

Section: Introductionmentioning

confidence: 99%

Mitochondrial genomes and genetic structure of the Kemp's ridley sea turtle (Lepidochelys kempii)

Frandsen

Figueroa

George

2019

Ecology and Evolution

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The Kemp's ridley (Lepidochelys kempii) is the world's most endangered sea turtle species and is primarily distributed in the Gulf of Mexico. In the United States, South Padre Island, Texas serves as a key nesting ground for the species. Genetic studies of the Kemp's ridley have been used to aid in conservation and management practices, with the mitochondrial control region as the most commonly used marker due to its perceived hypervariability and ease of sequencing. However, with the advent of next generation sequencing technology, targeting complete mitochondrial genomes is now feasible. Here, we describe a more complete mitochondrial genome for the Kemp's ridley than has been previously published in literature and demonstrate a cost-effective and efficient method for obtaining complete mitochondrial genomes from sea turtles. We compare the genetic diversity and taxonomic resolution obtained from whole mitochondrial genomes to that obtained from the mitochondrial control region alone. We compare current genetic diversity with previous records. Furthermore, we evaluate the genetic structure between the breeding stock in South Padre Island and that of deceased Kemp's ridleys recovered on the Northern coast of the Gulf of Mexico after the 2010 BP Deepwater Horizon oil spill, and of Kemp's ridleys stranded on the East Coast of the United States. Our results show that complete mitochondrial genomes provide greater resolution than the control region alone.They also show that the genetic diversity of the Kemp's ridley has remained stable, despite large population declines, and that the genetic makeup of deceased turtles stranded after the Deepwater Horizon oil spill is indistinguishable from the breeding stock in South Padre Island, Texas. K E Y W O R D Sconservation, control region, genetic diversity, next generation sequencing, phylogeny, phylogeography

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Kemp's Ridley Sea Turtle Saga and Setback: Novel Analyses of Cumulative Hatchlings Released and Time-Lagged Annual Nests in Tamaulipas, Mexico

Cited by 14 publications

References 228 publications

Density and exposure of surface-pelagic juvenile sea turtles to Deepwater Horizon oil

Density and exposure of surface-pelagic juvenile sea turtles to Deepwater Horizon oil

Variability in age and size at maturation, reproductive longevity, and long-term growth dynamics for Kemp's ridley sea turtles in the Gulf of Mexico

Mitochondrial genomes and genetic structure of the Kemp's ridley sea turtle (Lepidochelys kempii)

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