Dermochelys coriacea (Southeast Atlantic Ocean subpopulation)
|Scientific Name:||Dermochelys coriacea (Southeast Atlantic Ocean subpopulation)|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Tiwari, M., Wallace, B.P. & Girondot, M.|
|Reviewer(s):||Chaloupka, M.Y., Bolten, A.B., Dobbs, K., Limpus, C., Nel, R., Eckert, K.L., Mortimer, J.A., Pritchard, P.C.H., Dutton, P.H., van Dijk, P.P., Casale, P. & Miller, J.|
|Contributor(s):||Honarvar, S., Formia, A., Girard, A. & Beheret, N.|
The nesting epicenter for the Southeast Atlantic Leatherback subpopulation lies in Bioko Island, Equatorial Guinea, Gabon, and the Republic of Congo, with additional nesting in much smaller numbers extending north to Senegal and south to Angola (Turtle Expert Working Group 2007, Fretey et al. 2007a, Witt et al. 2009). Dutton et al. (2013) found that the West African rookeries sampled (Gabon and Ghana) were genetically different (mitochondrial DNA and microsatellites) from the other Atlantic rookeries and the South African rookery sampled, and that even Gabon and Ghana were fairly well differentiated based on mitochondrial DNA, but more weakly differentiated based on microsatellite data. The marine habitat for this subpopulation is thought to extend from the Atlantic coast of Africa south to the equator and southwest to Brazil, Uruguay, and Argentina and southeast to South African waters (Figure 1 in Supplementary Material), but the northern geographic boundaries lack resolution. Continuous long-term data sets, complete data on genetic stocks, and reliable estimates of the number of mature individuals are unavailable for this subpopulation. Furthermore, the majority of abundance in this subpopulation occurs in Gabon (TEWG 2007, Witt et al. 2009), for which long-term data are unavailable. Therefore this subpopulation is classified as Data Deficient for all applicable criteria (A, B, C, and D).
Criterion A could not be evaluated for this subpopulation because the majority of nesting in this subpopulation occurs in Gabon, for which trend data are unavailable. Although data were available from the other two major nesting sites (Table 1 in Supplementary Material), the cumulative abundance of these two sites is <10% the abundance in Gabon. Therefore, it was inappropriate to assign the trends observed in Congo and Equatorial Guinea to the entire subpopulation.
We assessed the status of the Southeast Atlantic Leatherback subpopulation by Criteria A-D; as no population viability analysis has been performed, Criterion E could not be applied.
Leatherbacks are distributed circumglobally, with nesting sites on tropical sandy beaches and migratory and foraging ranges that extend into temperate and sub-polar latitudes. The nesting epicentre for the Southeast Atlantic Leatherback subpopulation lies in Bioko Island, Equatorial Guinea, Gabon, and the Republic of Congo with nesting extending in smaller numbers north to Senegal and south to Angola (Turtle Expert Working Group 2007, Fretey et al. 2007a, Witt et al. 2009). See Eckert et al. (2012) for review of Leatherback geographic range, and Fretey et al. (2007a) for a regional review.
Native:Angola; Argentina; Benin; Brazil; Cameroon; Congo; Congo, The Democratic Republic of the; Côte d'Ivoire; Equatorial Guinea (Bioko); Gabon; Gambia; Ghana; Guinea; Guinea-Bissau; Liberia; Namibia; Nigeria; Saint Helena, Ascension and Tristan da Cunha; Sao Tomé and Principe; Senegal; Sierra Leone; South Africa; Togo; Uruguay
|FAO Marine Fishing Areas:|
Atlantic – western central; Atlantic – southwest; Atlantic – southeast; Atlantic – northwest; Atlantic – northeast; Atlantic – eastern central
|Range Map:||Click here to open the map viewer and explore range.|
Leatherbacks are a single species globally comprised of biologically described regional management units (RMUs; Wallace et al. 2010), which describe biologically and geographically explicit population segments by integrating information from nesting sites, mitochondrial and nuclear DNA studies, movements and habitat use by all life stages. RMUs are functionally equivalent to IUCN subpopulations, thus providing the appropriate demographic unit for Red List assessments. There are seven Leatherback subpopulations, including the Southeast Atlantic Ocean, Southwest Atlantic Ocean, Northwest Atlantic Ocean, Northeast Indian Ocean, Southwest Indian Ocean, East Pacific Ocean, and West Pacific Ocean. Multiple genetic stocks have been defined according to geographically disparate nesting areas around the world (Dutton et al. 1999) and in the Atlantic Ocean, in particular (Dutton et al. 2013), and are included within RMU delineations (Wallace et al. 2010; shapefiles can be viewed and downloaded at: http://seamap.env.duke.edu/swot).
|Current Population Trend:||Unknown|
|Habitat and Ecology:|
See the species account for a summary of the details. For a thorough review of Leatherback biology, please see Eckert et al. (2012).
|Generation Length (years):||30|
|Use and Trade:||Eggs and female turtles are harvested for human consumption as well as for use in traditional medicine and voodoo practices|
Threats to Leatherbacks (and other marine turtle species), vary in time and space, and in relative impact to populations. Threat categories were defined by Wallace et al. (2011) as the following:
1) Fisheries bycatch: incidental capture of marine turtles in fishing gear targeting other species;
2) Take: direct utilization of turtles or eggs for human use (i.e. consumption, commercial products);
3) Coastal Development: human-induced alteration of coastal environments due to construction, dredging, beach modification, etc.;
4) Pollution and Pathogens: marine pollution and debris that affect marine turtles (i.e. through ingestion or entanglement, disorientation caused by artificial lights), as well as impacts of pervasive pathogens (e.g. fibropapilloma virus) on turtle health;
5) Climate change: current and future impacts from climate change on marine turtles and their habitats (e.g. increasing sand temperatures on nesting beaches affecting hatchling sex ratios, sea level rise, storm frequency and intensity affecting nesting habitats, etc.).
The relative impacts of individual threats to all Leatherback subpopulations were assessed by Wallace et al. (2011). At a global scale, fisheries bycatch was classified as the highest threat to Leatherbacks globally, followed by human consumption of Leatherback eggs, meat, or other products and coastal development. Due to lack of information, pollution and pathogens was only scored in three subpopulations and climate change was only scored in two subpopulations. Enhanced efforts to assess the impacts of these threats on Leatherbacks—and other marine turtle species—should be a high priority for future research monitoring efforts.
For this Southeast Atlantic subpopulation, accidental capture in fisheries is one of the biggest threats (e.g., Carranza et al. 2006, Witt et al. 2011, Wallace et al. 2013, Riskas and Tiwari 2013), along with harvest of eggs and females for consumption as well as for use in traditional medicine and voodoo practices, oil exploitation activities, chemical and industrial pollution as well as sand mining (Fretey et al. 2007a,b; Wallace et al. 2011). The impact of these and other threats such as predation and erosion have not been sufficiently quantified.
Leatherbacks are protected under various national and international laws, treaties, agreements, and memoranda of understanding. A partial list of international conservation instruments that provide legislative protection for Leatherbacks are: Annex II of the SPAW Protocol to the Cartagena Convention (a protocol concerning specially protected areas and wildlife); Appendix I of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora); and Appendices I and II of the Convention on Migratory Species (CMS); the Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC), the Memorandum of Understanding on the Conservation and Management of Marine Turtles and their Habitats of the Indian Ocean and South-East Asia (IOSEA), the Memorandum of Understanding on ASEAN Sea Turtle Conservation and Protection, and the Memorandum of Understanding Concerning Conservation Measures for Marine Turtles of the Atlantic Coast of Africa.
Long-term efforts to reduce or eliminate threats to Leatherbacks on nesting beaches have been successful (e.g. Dutton et al. 2005, Chacón-Chaverri and Eckert 2007, Sarti Martínez et al. 2007). Reducing Leatherback bycatch has become a primary focus for many conservation projects around the world, and some mitigation efforts are showing promise (Watson et al. 2005; Gilman et al. 2006, 2011). However, threats to Leatherbacks—bycatch and egg consumption and female exploitation, in particular, persist, and in some places, continue to hinder population recovery (Bellagio report 2007, Bal et al. 2007, Fretey et al. 2007, Alfaro-Shigueto et al. 2011, Wallace et al. 2013, Riskas and Tiwari 2013). For depleted Leatherback populations to recover, the most prevalent and impactful threats must be reduced wherever they occur, whether on nesting beaches or in feeding, migratory, or other habitats (Steering Committee, Bellagio Conference on Sea Turtles 2004; Bellagio report 2007; Wallace et al. 2011, 2013); a holistic approach that addresses threats at all life history stages needs to be implemented (Dutton and Squires 2011). Finally, high poverty levels in Africa place enormous pressure on sea turtle populations and would need to be recognized and addressed by conservation and management programs (Formia et al. 2003).
|Citation:||Tiwari, M., Wallace, B.P. & Girondot, M. 2013. Dermochelys coriacea (Southeast Atlantic Ocean subpopulation). The IUCN Red List of Threatened Species 2013: e.T46967848A46967852.Downloaded on 24 June 2018.|
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