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Long-Distance Movements of Galapagos Green Turtles
Abstract and Figures
Twenty-three turtles were recovered from a total of 5844 green turtles (Chelonia mydas agassizii) tagged in the Galápagos Islands between 1970 and 1979. Three recoveries are from Costa Rica, four from Panama, one from Colombia, five from mainland Ecuador and ten from Peru. As with other green turtle populations, the Galápagos breeding colony (or at least part of it) undertakes long-distance movements to, and is thus recruited from, distant and widespread feeding grounds. Minimum distances range from 1233 to 2143 km and the times between last recorded sighting and recapture from 98 days to 3183 days. One turtle, recaptured off the coast of mainland Ecuador after nesting in Galápagos and re-released, subsequently renested in Galápagos, thus representing one of the few documented instances of two-way migration. Three of the recoveries are males; only two other males have made longer recorded one-way journeys. The recapture rate of 0.5% for males and 0.4% for nesting females is lower than for green turtles elsewhere.
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... The Galapagos Marine Reserve (GMR) hosts one of the most important populations of C. mydas in the tropical eastern Pacific (TEP), which contains approximately 40% of the individuals of this region Zárate et al., 2013). This marine protected area is also one of the most important feeding grounds for green turtles in the TEP, particularly around the archipelago's western islands (Green, 1984;Seminoff et al., 2008), where high productivity areas are located due to local upwelling systems (Palacios et al., 2006;Schaeffer et al., 2008). Given the absence of seagrass, foraging grounds in the GMR are usually bays composed of algae patches, where green turtles feed on shallow coastal macroalgae (Green, 1984). ...
... This marine protected area is also one of the most important feeding grounds for green turtles in the TEP, particularly around the archipelago's western islands (Green, 1984;Seminoff et al., 2008), where high productivity areas are located due to local upwelling systems (Palacios et al., 2006;Schaeffer et al., 2008). Given the absence of seagrass, foraging grounds in the GMR are usually bays composed of algae patches, where green turtles feed on shallow coastal macroalgae (Green, 1984). A stomach content analysis revealed a coastal neritic diet composed predominately of green and red algae (i.e., Ulva lactuca and Polysiphonia sp.), complemented by small amounts of red mangrove (Rhizophora mangle) and gelatinous invertebrates (Carrión-Cortez et al., 2010). ...
... There are few movement studies available for Galapagos green turtles; however, the distribution data available indicate some restriction to warmer waters near 26°C (Green, 1984;Seminoff et al., 2008), and different postnesting migration strategies, which include north-bound migrations to Central America, residency in the Galapagos Islands, and dispersal to oceanic waters southwest of the archipelago . Warm waters of Central America provide important developmental habitats for green turtles and may serve a similar function in juvenile and adult stages (Amorocho & Reina, 2007;Green, 1984;vander Zanden et al., 2013). ...
Knowledge of feeding patterns of highly migratory species is critical for understanding their habitat use and informing the management of their populations. The Galapagos Islands are one of the most important nesting and feeding areas for green turtles (Chelonia mydas) across the tropical eastern Pacific, yet little is known about the feeding patterns of this species. The isotopic composition of different tissues has been used to gain insight into the trophic dynamics of mobile aquatic consumers whose trophic behavior is difficult to directly measure. To elucidate the temporal feeding patterns and isotopic niche sizes of Galapagos green turtles, stable isotope analyses were performed on multiple tissues (skin and carapace) collected at the two most important nesting areas in the archipelago: Bachas and Quinta Playa. The δ¹³C and δ¹⁵N signatures on the skin and carapace samples from 56 adult females revealed significant differences between tissues (p = .001 and p = .021, respectively) and nesting areas (p = .011 and p = .003, respectively). These differences suggest a shift from oceanic feeding grounds to neritic habitats before nesting. The carapace isotope values indicated an offshore feeding strategy and a greater isotopic niche (SEAc = 1.91‰²), whereas the skin isotope values represented an inshore feeding strategy with a narrower niche (SEAc = 1.37‰²), likely related to the consumption of specific coastal prey. Our results suggest that Galapagos green turtles feed across different habitats, and this information can be applied to improve the management of this endangered species.
Research Highlights
• Determining the feeding patterns of Galapagos green turtles is critical for understanding their habitat use.
• Isotopic signatures suggest a shift from oceanic feeding grounds to neritic habitats before nesting.
• Different feeding patterns over time in Galapagos green turtles allow them to reduce competitive interactions.
... The success of flipper tagging programs is influenced by tag loss (when an individual loses a portion or all of its initial marking), which varies between tag type, studied species, and where the tag is attached to the turtle (Green 1979;Limpus 1992;Strong et al. 1993, Pfaller et al. 2018. Furthermore, the recapture rate (proportion of tagged individuals recovered of all individuals tagged) of flipper tagged sea turtles between nesting beaches and foraging grounds is generally low, especially in Black Turtles as few in-water monitoring projects exist within the Black Turtles' range. ...
... An initial study comparing tag type and position at Colola conducted by Alvarado et al. (1988) found that monel metal tags applied in front flippers were lost by more than 44% compared to plastic tags in hind flippers, where tag loss was about 2.8%. Similar results were found by Green (1979). These authors attributed tag loss to the type of tag rather than tag position. ...
... These authors attributed tag loss to the type of tag rather than tag position. Similarly, Green (1984) and Alvarado-Díaz and Figueroa (1992) mention the application of both metal and plastic tags, respectively, on front and hind flippers, yet it is unclear which tag position proved most effective in their long-distance tag recovery studies. Following this uncertainty, Strong et al. (1993) compared the retention of metal tags on all four flippers of nesting females and found that tags applied to the left hind flipper are retained longest, although differences were not significant, possibly due to small sample size and short sampling period (one nesting season). ...
... En el Pacifico este una de las tortugas más abundantes es la tortuga verde (Chelonia mydas agassizii), cuyas principales zonas de reproducción están en las islas Galápagos, Ecuador (Green, 1984;Seminoff, 2004), Michoacán, México (Alvarado-Diaz et al., 2001), Nor Oeste de Costa Rica (Blanco et al., 2012;Santidrian -Tomillo et al., 2015) e islas Revillagigedo, México (Holroyd & Trefry, 2010). Posteriormente ya como juvenil esta especie se recluta en zonas costeras en el Pacifico este, que son importantes áreas de alimentación para la especie (De Paz et al., 2007;Velez-Zuazo et al., 2014). ...
... In the eastern Pacific, the green sea turtle (Chelonia mydas agassizii) is one of the most abundant turtles, whose main reproductive areas are in the Galapagos Islands, Ecuador (Green, 1984;Seminoff, 2004), Michoacán, México (Alvarado-Diaz et al., 2001), northwestern Costa Rica (Blanco et al., 2012;Santidrian -Tomillo et al., 2015), and Revillagigedo Islands, Mexico (Holroyd & Trefry, 2010). Then, as a juvenile, this species is recruited in coastal areas in the eastern Pacific, which are important feeding areas for the species (De Paz et al., 2007;Velez-Zuazo et al., 2014). ...
Se estudiaron los hábitos alimentarios de la tortuga verde del Pacifico Este Chelonia mydas agassizii (Boucort, 1868) durante el periodo 2013 - 2018 en el estuario de Virrilá, Sechura. Se practicó la técnica de lavado esofágico a 119 ejemplares vivos. La mayoría de los ejemplares analizados fueron sub – adultos (61,9%), seguidos por juveniles (29,2%) y adultos (8,8%). Las tortugas presentaron hábitos omnívoros, pero con alta predominancia de consumo de materia vegetal. Se identificaron 47 ítems alimentarios, agrupados en nueve Phylum, siendo las algas verdes Ulva sp. y Caulerpa filiformis los ítems principales con (Ai = 18%; Ip = 57%) y (Ai = 11%; Ip = 22%), respectivamente. Seguido de pasto marino Ruppia maritima (Ai = 11%; Ip = 13%),restos de cnidarios como anémonas Actinia sp. (Ai = 4%; Ip = 0,3%). Existió marcada estacionalidad en el consumo de presas, en verano – otoño se consumió C. filiformis (Ip = 78,4%), en invierno - primavera Ulva sp. (Ip = 52,3%) y R. maritima (Ip = 39,9%). También se encontró fragmentos de plástico (24%). El estuario de Virrilá representa una importante área de alimentación para tortugas verdes en etapas medias de desarrollo ontogénico, con predominancia de sub-adultos, convirtiéndose en área prioritaria para la conservación de esta especie amenazada.
... Dermochelys coriacea, Eretmochelys imbricata) (CITES 2002;CPPS 2006;IUCN 2012). The Galapagos Islands are an important nesting ground for the green sea turtle (Chelonia mydas) in the Eastern Pacific (Green and Ortiz-Crespo 1982;Green 1984;Zarate et al. 2002;Seminoff et al. 2007). Similarly, this species is also abundant at foraging and breeding grounds. ...
The following research aims, for the first time in the Galapagos Islands Ecuador, to investigate the uncertain adult male sea turtle home ranges. We had undertaken ± 190 hours of active tracking on Chelonia mydas adult male specimens in their reproductive season. Fifty Alpha Hull was selected as the most accurate core area estimate, this ranged from 0.08 to 0.28 km2; core areas proximity to shore ranged from 0.33 to 0.91 kilometers and core area bathymetry ranged from 10 to 60 meters. We observed a selected overlap in home range areas. Our data indicated two distinct types of movements. Two turtles showed spherical movements with a high fidelity to the capture-release location plus a net displacement, which ranged from 0.17 to 0.30 Km. Another turtle showed low fidelity to the capture-release location with a net displacement of 22.35 km. Turtles in this study moved significantly further during diurnal vagility versus nocturnal vagility. However, there were no significant differences between diurnal net vagility versus nocturnal net vagility and diurnal travel speeds versus nocturnal travel speeds.
Key words: Chelonia mydas, Adult Male, Home Range, Active Tracking, Management, Galapagos Islands.
... The green turtle populations of Pacific Central America are considered understudied because published records in scientific journals are scarce. In the eastern Pacific, the primary continental rookeries for this species are located in Michoacán, México (Alvarado-Díaz et al. 2001;Delgado Trejo and Alvarado Díaz 2012); other important nesting grounds identified in the eastern Pacific region are found in the Galápagos Islands, Ecuador (Green 1984;Zárate et al. 2013) and the Revillagigedos Archipelago, Mexico (Holroyd and Trefry 2010). ...
Here we report on a newly discovered nesting population of east Pacific green turtles (Chelonia mydas) in northwest Costa Rica at San José Island, Murcíelago Archipelago, that rivals those of Mexico and the Galápagos Islands, Ecuador. A total of 1232 individual green turtles were tagged over 4 nesting seasons (2012–2013 to 2015–2016). Mean (± SD) annual number of nests (1077 ± 414; range, 490-1698 nests) and females (306 ± 133; range, 164-466 females) was higher than those previously reported for Pacific Costa Rica. The number of deposited nests was similar to that registered on the Galápagos main beaches, but density of nests (number of nests/km) was the second highest for any green turtle beach in the eastern Pacific. Reproductive output was similar (mean clutch frequency: 4.4 ± 2.2 clutches and mean clutch size: 75.8 ± 14.6 eggs/clutch), and mean hatching success was higher (0.89 ± 0.14) than those reported at other sites in the eastern Pacific. Because the study site was located on an island within a protected area, several of the common threats that sea turtles face at more accessible mainland sites (i.e., egg poaching, tourist development, and predation by large mammals) were absent. Our data indicate that San José Island is the most important nesting site for east Pacific green turtles in Central America. The large size of this population, along with its isolated and protected status, suggest that this rookery is making a significant contribution to the conservation of east Pacific green turtles. Additional information at the country level will help determine the relative importance of Costa Rica for green turtle nesting in the broad eastern Pacific region.
... The green sea turtle is a highly migratory species in the eastern Pacific using different habitats during their life cycle [8,36]. Origins of eastern Pacific green turtle individuals observed in Chilean waters have been assumed to come from the nesting population of Galápagos Islands [40], because multiple records of specimens tagged in Galápagos have been recaptured in Peruvian coastal waters [41]. Although no record exists of tagged eastern Pacific green turtles from Chilean coastal areas [14], this migratory pattern is supported by recent analyses of mtDNA from samples taken in the north of Chile (e.g., Ref. [22]). ...
... Turtles that nest in Michoacán tend to migrate to Baja California and to the south, primarily to Guatemala and El Salvador (Alvarado and Figueroa 1992), whereas individuals from the Revillagigedo Archipelago, Mexico, have an affinity for the west coast of the U.S. (Juárez-Cerón et al. 2003). Some turtles from the Galapagos Islands, Ecuador, travel to neritic foraging areas in Central and South America (Green 1984;Amorocho et al. 2012); however, not all individuals exhibit this pattern. For example, Seminoff et al. (2008) identified three post-nesting migration strategies in the Galapagos: ...
The primary foraging areas of Green Turtle (Chelonia mydas) in the Mexican Pacific are located near the Baja California Peninsula, although foraging areas also have been documented along the southern coast of the country. The goal of this study was to determine demographic characteristics, catch per unit of effort (CPUE), condition index (CI), and food preferences of Green Turtles in Chacahua Lagoon, Oaxaca, Mexico. This is the first study of its kind involving a foraging aggregation along the Pacific Coast of southern Mexico. Between June 2009 and May 2010, we captured 16 Green Turtles with entanglement nets and had 25 total captures. Individuals that we captured more than once spent up to six months in the lagoon. Based on size, we classified 14 turtles as adults and two as juveniles. We could not determine the sex of all turtles. The mean monthly CPUE was 0.095 turtles/100 m net/12 h, which was one to two orders of magnitude lower than those reported for Baja California foraging areas. The mean CI was 1.38, similar to that reported for other Eastern Pacific foraging sites. Eight turtles exhibited injuries, mainly on the carapace and likely from outboard engine boats. Samples of esophageal and oral cavity contents that we collected from some turtles revealed that they consumed Gracillariopsis lemaneiformis, a macroalgae species distributed in several patches throughout the lagoon. Our study provides data on a foraging aggregation of Green Turtles that may be used to guide conservation efforts and research in an under-studied region.
... La tortuga verde del Pacífico oriental Chelonia mydas agassizii (Boucort 1868) es la forma melanística del género Chelonia y se distribuye desde San Diego, California hasta Chile y por el oeste hasta las islas Revillagigedo e islas Galápagos (Cliffton et al. 1982, Cornelius 1982, Green 1984, Márquez 1990, Pritchard 1999, Seminoff 2004, Holroyd y Trefry, 2010. En Perú, se han registrado varias áreas de alimentación a lo largo de la costa peruana, como en las costas de Tumbes (Punta Sal, Punta Mero, Bocapán, Puerto Pizarro y Casitas), Punta Restín al norte del departamento de Piura (Hays-Brown y Brown 1982, Aranda y Chandler 1989, de Paz y Alfaro-Shigueto 2008, en la provincia de Talara (Velez-Zuazo et al. 2014) en la bahía de Sechura y estuario de Virrilá al sur del departamento de Piura (Santillán 2008, Cáceres et al. 2013, Isla Lobos de Tierra al norte del departamento de Lambayeque , la bahía de Paracas y Tambo de Mora en el departamento de Ica (Hays-Brown y Brown 1982, Aranda y Chandler 1989, de Paz et al. 2007, Quiñones et al. 2013, Velez-Zuazo et al. 2014). ...
Se registra por primera vez para Perú a Cricocephalus albus (Digenea: Pronocephalidae) en la tortuga verde del Pacífico oriental (Chelonia mydas agassizii). Los parásitos fueron colectados durante la necropsia de una tortuga verde varada en el estuario de Virrilá localizado en la provincia de Sechura, Departamento de Piura, Perú. El presente trabajo realiza una breve descripción de C. albus, así como la discusión de sus hospederos y distribución geográfica.
Although sea turtle flipper tagging is a tenet field technique generating irreplaceable scientific data worldwide since the inception of sea turtle conservation in 1920s along the Great Barrier Reef, the procedure was reported to trigger outbreaks of sea turtle fibropapillomatosis (FP) in 2018. This global environmental impact assessment performed during 2020–2023 meta‐analyzed three impacts on sea turtles health and conservation of the presence of visible flipper tags: a risk of clinical expression of FP lesions at the tag insertion point, a deterrent effect of the presence of flipper tags on sea turtle fishing, and a risk of entanglement of sea turtles in fishing gears. This essay concluded that the risk of expression of a FP lesion at the flipper tag insertion point is most probably correlated to a direct inoculation of ChHV5 via infected tagging equipment, and that the risk of entanglement in fishing gears can be mitigated by the choice of metallic flipper tags over plastic flipper tags. This essay also strongly recalls the sea turtle flipper tagging technique represents a remedy to knowledge gaps relevant to climate velocity research and can be a deterrent on sea turtle fishing in a frame of strong partnerships with indigenous people, independently of communities' socio‐cultural backgrounds.
To address aspects of the evolution and natural history of green turtles, we assayed mitochondrial (mt) DNA genotypes from 226 specimens representing 15 major rookeries around the world. Phylogenetic analyses of these data revealed (1) a comparatively low level of mtDNA variability and a slow mtDNA evolutionary rate (relative to estimates for many other vertebrates); (2) a fundamental phylogenetic split distinguishing all green turtles in the Atlantic-Mediterranean from those in the Indian-Pacific Oceans; (3) no evidence for matrilineal distinctiveness of a commonly recognized taxonomic form in the East Pacific (the black turtle C.m. agassizi or C. agassizi); (4) in opposition to published hypotheses, a recent origin for the Ascension Island rookery, and its close genetic relationship to a geographically proximate rookery in Brazil; and (5) a geographic population substructure within each ocean basin (typically involving fixed or nearly fixed genotypic differences between nesting populations) that suggests a strong propensity for natal homing by females. Overall, the global matriarchal phylogeny of Chelonia mydas appears to have been shaped by both geography (ocean basin separations) and behavior (natal homing on regional or rookery-specific scales). The shallow evolutionary population structure within ocean basins likely results from demographic turnover (extinction and colonization) of rookeries over time frames that are short by evolutionary standards but long by ecological standards.
Capture-recapture measurements of 11 wild green turtles, Chelonia mydas, and of 28 wild loggerhead turtles, Caretta caretta, in Florida indicate that growth in straight-line carapace length fits von Bertalanffy growth models better than logistic models. The von Bertalanffy model for green turtle growth yields estimates for age at maturity of between 18 and 27 years, based on the carapace length of the smallest nesting female (88 cm) and the mean length of all nesting females (99 cm). The model for loggerheads yields estimates of between 12 and 30 years, also based on carapace measurements of the smallest nesting female (74 cm) and the mean carapace length of all nesting females (92 cm). It is suggested that the upper estimates provide more realistic indications of mean age at first maturity.
Six recoveries of leatherback turtles tagged while nesting in the Guianas and caught in the United States, Mexico, Venezuela, and Ghana are among the longest recorded migrations for turtles of any kind. Seventy-two ridley turtles from the same nesting area were recaptured as far west as Barbados, Trinidad, and Isla Margarita, and as far east as Amapá, Brazil. Ninety-one green turtles were recovered, all but one from Brazil, and with a very high proportion from the States of Ceará and Alagoas, where they mingle with green turtles from the Ascension Island nesting ground.