MTN 163:18-20 Southernmost Record of an Immature Green Turtle Chelonia mydas in the Maracaibo Lake System, Venezuela

seaturtle.org : MTN : ARCHIVES : Sign In

Marine Turtle Newsletter-Online

Southernmost Record of an Immature Green Turtle Chelonia mydas in the Maracaibo Lake System, Venezuela

Ninive Espinoza-Rodriguez^1,2 & Héctor Barrios-Garrido^1,2,3
¹Grupo de Trabajo en Tortugas Marinas del Golfo de Venezuela (GTTM-GV), Urb. Villa Venecia, Calle 40B #15A-41, Maracaibo 4001, Venezuela (E-mail: espinozaninive@gmail.com);
²Laboratorio de Ecología General, Centro de Modelado Científico ^CMC, Facultad Experimental de Ciencias, La Universidad del Zulia, Apartado 526, Maracaibo 4001, Venezuela (E-mail: hbarriosg@fec.luz.edu.ve)
³College of Marine and Environmental Sciences, Centre for Tropical Water and Aquatic Ecosystem Research ^TropWATER, James Cook University, Townsville, Queensland 4811, Australia (E-mail: hector.barriosgarrido@my.jcu.edu.au)

The Maracaibo Lake System, which is an extensive coast depression (9-12°N, 70-72°W) in the west of Venezuela (Rodriguez 2001), covers four interconnected aquatic ecosystems: (1) the Gulf of Venezuela, (2) “El Tablazo” Bay, (3) The Maracaibo Strait, and (4) Maracaibo Lake (Rodriguez 2000a, 2001) (Fig. 1). Historically, records of marine turtles were restricted to the Gulf of Venezuela and “El Tablazo” Bay (Viloria & Barros 2000), which have unique environmental conditions and ecosystems such as seagrass beds, coral reef patches, sandy grounds, and rocky shores, that support both marine and estuarine fauna (Espinoza-Rodriguez et al. 2015, 2019; Barrios-Garrido et al. 2020a). Contrarily, the Maracaibo Strait and Maracaibo Lake are predominantly freshwater ecosystems, where muddy bottoms, coastal lagoons, floodplain and mangrove forests cover most of its coastline (Medina & Barboza 2003, 2006). Both estuarine and freshwater animals are commonly found in the previously mentioned ecosystems (Montiel-Villalobos & Barrios- Garrido 2005; De Turris et al. 2010).

Figure 1. Maracaibo Lake System indicating its four aquatic ecosystems. The marine turtle icon indicates the location where the juvenile green turtle was found and rescued (Source: MapTool - seaturtle.org)

The Gulf of Venezuela is largely influenced by salt water supplied from the Caribbean Sea (Rodriguez 2000a). Previous studies have shown the presence of five marine turtle species in the Gulf of Venezuela, where the green turtle (Chelonia mydas) is the most frequently observed with more than 80% of the total observations including direct sightings, incidental by-catch, direct fishing, strandings, among others (Barrios-Garrido et al. 2020a; Rojas- Cañizales et al. 2020). It is also common to find a wide distribution of sizes (juveniles, sub-adults, to adults) all year-round (Barrios- Garrido et al. 2020a,b). Previous authors have indicated through tag reports and genetic studies, that marine turtles from different populations (such as Isla de Aves-Venezuela, Tortuguero-Costa Rica, Panama, Florida, etc.) use the Gulf of Venezuela as a feeding and development area (Barrios-Garrido et al. 2020a,b; Rojas-Cañizales et al. 2020). This note reports on the southernmost record of an immature green turtle, Chelonia mydas, in the Maracaibo Lake System, Venezuela.

Records and reports on marine megafauna in the Maracaibo Lake System have been documented following the Opportunistic Notification Network (RAO, by its Spanish acronym) methodology (Barrios-Garrido et al. 2012). In the case of marine turtles, when an individual is captured or is found stranded by community members and documented in the RAO protocol, it is measured for curved carapace length (CCL), curved carapace width (CCW), weighed (kg), and head profiles are photographed when possible. If the turtle is alive, the attending veterinarian has to conduct a preliminary examination, and decide whether the turtle needs rehabilitation or not (Barrios-Garrido et al. 2012; Espinoza-Rodriguez & Barrios- Garrido 2012; Conde et al. 2019).

On 6 November 2008, an immature green turtle was captured by artisanal fishers in Boscan village (9.301444°N, 71.083611°W) (Fig. 1). Biometric measurements of the specimen were made using a flexible measuring tape graduated in millimeters and it was weighed using a portable 110lb/50kg hanging scale. The specimen had a total curved carapace length of 24.9 cm, curved carapace width of 21.5 cm, and weighed 1.7 kg (Fig. 2). The turtle was then transported to a rehabilitation facility and kept under observation for two days, due to its poor body condition and signs of physical fatigue, which might be due to the time it spent in the area before being captured by local fishers (Thomson et al. 2009). Once the turtle’s physical appearance showed improvement and the veterinarian approved its release, the turtle was released on 8 November 2008.

Figure 2. Immature green turtle (Chelonia mydas) recorded on the 8 November 2008, Southern Maracaibo Lake, Venezuela. Photos taken by: N. Espinoza-Rodriguez 2008.

This is the first and only record of a marine turtle inside Maracaibo Lake in our database. We confirmed the identification of the specimen by the number and arrangement of lateral scutes in the carapace, the number of prefrontal scales, and the characteristic color patterns for the species. This event was considered an unusual record and might have occurred due to various causes such as the local currents in the Maracaibo Strait, changes in the salinity concentration while foraging, or some other unexpected situation preventing the individual to return to the marine ecosystem northern Maracaibo Lake System.

These unusual records are important in order to understand green turtle’s habitat use of the Maracaibo Lake System (Barrios-Garrido et al. 2020a,b). During informal interviews to several local fishers regarding green turtle presence in the area, they affirmed that they know of this species but it is rarely seen, with one or two individuals per year maybe found deceased in their nets, and only during the rainy season (July-November). They also indicated that there is no local consumption of this species. They believe that its presence in the area is a consequence of the navigation channel opened in 1958 (Morillo Diaz & Salas Cohen 2009), which marine fauna use to enter Maracaibo Lake (Febres & Masciangioli 2000; Morillo Diaz & Salas Cohen 2009).

It is known that marine turtles occur in tropical and subtropical saltwater or brackish environments (Meylan & Meylan 2000; Bolten 2003). However, there is little research about marine turtles using freshwater bodies like delta rivers and estuarine lagoons (Carr 1965; Costas Campos et al. 2013). The area where the specimen was found is characterized by low salinities (ranging between 1-4 psu), calm waters, average depths not more than 5 m, with muddy substrates (Febres & Masciangioli 2000; Medina & Barboza 2003). In addition, this region is a very important oil reserve, and has caused several environmental disruptions due to daily small oil spills and frequent use by vessels and oil ships (Rodriguez 2000b). These conditions are not considered as healthy settings for the recruitment and development of marine turtles (Carr 1965; Bjorndal & Jackson 2003). This record of an immature green turtle inside the Maracaibo Lake might indicate their tolerance to lower salinity systems, and how this species potentially uses the navigation channel that would allow local migrations to these freshwater and /or estuarine areas (Carr 1965; Costas Campos et al. 2013). Nevertheless, we cannot confirm the latter suggestions mainly because it is impossible for us to know the specimen’s exact trajectory before the encounter and if it was an active or passive migration toward this southern region. It still remains unclear how and if green turtles use all four water bodies that make up the Maracaibo Lake System.

Acknowledgements. The authors acknowledge the inhabitants of the fishing port in Boscan village in Maracaibo Lake, who contributed to the conservation work in the region. Thanks to the students and professors of the Ecology Laboratory from the Biology Department of the Experimental Faculty of Science at the University of Zulia who collaborated during this event either collecting the specimen or collaborating during its rehabilitation period; as well as every helping hand from the Research Division at the Post-grade Department and the Dean office of this distinguish faculty. We thank editor and reviewers’ comments to improve our manuscript. This research was authorized by Venezuela’s Environmental Ministry (Ministerio del Poder Popular para el Ambiente) via scientific hunting licenses 0916 and 1224. Figure 1 was prepared using MapTool, via seaturtle.org.

BARRIOS-GARRIDO, H., N. WILDERMANN, N. ESPINOZA, J. PALMAR & L. MORÁN. 2012. New techniques for the rescue of sea turtles and field data assessment to estimate their population status in the Gulf of Venezuela. In: Jones, T.T. & B.P. Wallace (Comps.). Proceedings of the 31st Annual Symposium on Sea Turtle Biology and Conservation. NOAA Tech Memo NMFS- SEFSC-631, pp. 81-82.

BARRIOS-GARRIDO, H., P. BECKER, K.A. BJORNDAL, A.B. BOLTEN, C.E. DIEZ, N. ESPINOZA-RODRIGUEZ, M. FASTIGI, J. GRAY, E. HARRISON, K.A. HART, A. MEYLAN, P. MEYLAN, M.G. MONTIEL-VILLALOBOS, F. MORALES, M. NAVA, J. PALMAR, M.J. PETIT-RODRIGUEZ, P. RICHARDSON, K.M. RODRIGUEZ-CLARK, D. ROJAS- CAÑIZALES, M.G. SANDOVAL, R.A. VALVERDE, R. VAN DAM, J.T. WALKER, N. WILDERMANN & M. HAMMAN. 2020a. Sources and movements of marine turtles in the Gulf of Venezuela: Regional and local assessments. Regional Studies in Marine Science 36: 101318.

BARRIOS-GARRIDO, H.A., M.G. MONTIEL-VILLALOBOS, J. PALMAR & K.M. RODRÍGUEZ-CLARK. 2020b. Wayuú capture of green turtles, Chelonia mydas, in the Gulf of Venezuela: A major Caribbean artisanal turtle fishery. Ocean & Coastal Management 188: 105123.

BJORNDAL, K.A. & J.B.C. JACKSON. 2003. Roles of sea turtles in marine ecosystems: Reconstructing the past. In: Lutz, P.L., J.A. Musick & J. Wyneken (Eds.). Biology of Sea Turtles Volume 2. CRC Press, Boca Raton, FL. pp. 259-274.

BOLTEN, A.B. 2003. Variation in sea turtle life history patterns: neritic vs. oceanic developmental stages. In: Lutz, P., J.A. Musick & J. Wyneken (Eds.). Biology of Sea Turtles. Volume 2. CRC Press, Boca Raton, FL. pp. 243-258.

CARR, A. 1965. The navigation of the green turtle. Scientific American 212(5): 78-87.

CONDE, B., M.C. ALVARADO, N. ESPINOZA-RODRIGUEZ & H. BARRIOS-GARRIDO. 2019. Primer reporte de coccidiosis en tortugas verdes (Chelonia mydas) del Golfo de Venezuela. Caldasia 42: 278-288.

COSTAS CAMPOS, C.E., R. CABRAL DOS SANTOS, A. SILVA ARAUJO & N.N. GUEDES PAES. 2013. First record of an immature green turtle Chelonia mydas (Linnaeus, 1758) (Testudines: Cheloniidae) on a fluvial island, Reserva Biológica do Parazinho, Amazonas river, Brazil. CheckList 9: 434-435.

DE TURRIS-MORALES, K., G. DELGADO-ORTEGA, N. ESPINOZA-RODRIGUEZ, M.G. MONTIEL-VILLALOBOS & H. BARRIOS-GARRIDO. 2010. Nota sobre el comportamiento alimenticio del delfin estuarino (Sotalia guianensis) en la costa occidental del Lago de Maracaibo. Ecotropicos 23: 114-116.

ESPINOZA-RODRIGUEZ, N. & H. BARRIOS-GARRIDO. 2012. Tag recovery and photographic identification: tools to validate residency and recapture of sea turtles in the Gulf of Venezuela. In: Jones, T.T. & B.P. Wallace (Comps.). Proceedings of the 31st Annual Symposium on Sea Turtle Biology and Conservation. NOAA Tech Memo NMFS-SEFSC-631, pp. 245.

ESPINOZA-RODRIGUEZ, N., J. CARRASQUERO, K. DE TURRIS-MORALES, G. DELGADO-ORTEGA & H. BARRIOS-GARRIDO. 2015. Asociaciones entre aves marinas y Sotalia guianensis en el sur del Golfo de Venezuela. Caldasia 37: 309-318.

ESPINOZA-RODRÍGUEZ N., K. DE TURRIS-MORALES, T. SHIMADA & H. BARRIOS-GARRIDO. 2019. Guiana dolphin (Sotalia guianensis) in the Southern Gulf of Venezuela: Seasonal distribution, group size, and habitat use. Regional Studies in Marine Science 32: 100874.

FEBRES, G. & P. MASCIANGIOLI. 2000. Hidrografía del sistema de Maracaibo. In: Rodríguez G. (Ed). El Sistema de Maracaibo. Caracas, Venezuela: Instituto Venezolano de Investigaciones Científicas (IVIC). pp. 33-59.

MEDINA, E. & F. BARBOZA. 2003. Manglares del sistema del Lago de Maracaibo: caracterización fisiográfica y ecológica. Ecotropicos 16: 75-82.

MEDINA, E. & F. BARBOZA. 2006. Lagunas costeras del Lago de Maracaibo: distribución, estatus, y perspectivas de conservación. Ecotropicos 19: 128-139.

MEYLAN, A. & P. MEYLAN. 2000. Introducción a la evolución, historias de vida y biología de las tortugas marinas. In: Eckert, K.L., K.A. Bjorndal, F.A. Abreu-Grobois & M. Donnelly (Eds.). Técnicas de Investigación y Manejo para la Conservación de las Tortugas Marinas. UICN/CSE Grupo Especialista en Tortugas Marinas Publicación No. 4. pp. 3-5.

MONTIEL-VILLALOBOS, M.G. & H. BARRIOS-GARRIDO. 2005. Obsevaciones sobre la distribución y situación actual del manati Trichechus manatus (Sirenia: Trichechidae) en el Sistema del Lago de Maracaibo. ANARTIA. Publicaciones Ocasionales del Museo de Biología de la Universidad del Zulia. Facultad Experimental de Ciencias 18: 1-12.

MORILLO DIAZ, G. & G. SALAS COHEN. 2009. La cuenca del lago de Maracaibo como unidad geohistorica. Agenda Social 3: 78-99.

RODRÍGUEZ, G. 2000a. Fisiografía del sistema de Maracaibo. In: Rodriguez, G. (Ed.) El Sistema de Maracaibo. Instituto Venezolano de Investigaciones Científicas (IVIC) Caracas, Venezuela. pp. 7-20.

RODRÍGUEZ, G. 2000b. El manejo de los recursos naturales del sistema de Maracaibo. In: Rodriguez, G. (Ed.) El Sistema de Maracaibo. Instituto Venezolano de Investigaciones Científicas (IVIC) Caracas, Venezuela. pp. 91-109.

RODRÍGUEZ, G. 2001. El lago de Maracaibo como cuenca anaeróbica natural: Uso de líneas de base históricas en estudios de impacto ambiental. Interciencia 26: 450-456.

ROJAS-CAÑIZALES, D., N. ESPINOZA-RODRIGUEZ, M.J. RODRIGUEZ-PETIT, J. PALMAR, C. MEJIAS-BALSALOBRE, N. WILDERMANN, T. BARROS & H. BARRIOS-GARRIDO. 2020. Marine turtle mortality in a southern Caribbean artisanal fishery: A threat for immature green turtles. Regional Studies in Marine Science 38: 101380.

THOMSON, J.A., D. BURKHOLDER, M.R. HEITHAUS & L.M. DILL. 2009. Validation of a rapid visual-assessment technique for categorizing the body condition of green turtles (Chelonia mydas) in the Field. Copeia 2009: 251-255.

VILORIA, A. & T. BARROS. 2000. La fauna estuarina: otros vertebrados. In: Rodríguez, G. (Ed.). El Sistema de Maracaibo. Instituto Venezolano de Investigaciones Científicas (IVIC) Caracas-Venezuela. pp. 243-245.