Dermochelys coriacea (Southwest Atlantic Ocean subpopulation)
|Scientific Name:||Dermochelys coriacea (Southwest Atlantic Ocean subpopulation)|
|Red List Category & Criteria:||Critically Endangered D ver 3.1|
|Assessor(s):||Tiwari, M., Wallace, B.P. & Girondot, M.|
|Reviewer(s):||Casale, P., Dutton, P.H., Eckert, K.L., Miller, J., Mortimer, J.A., Nel, R., Pritchard, P.C.H., van Dijk, P.P., Bolten, A.B., Musick, J.A., Limpus, C. & Dobbs, K.|
|Contributor(s):||Marcovaldi, M., Fallabrino, A., Lopez-Mendilaharsu, M., de Padua Almeida, A. & Thome, J.|
The Southwest Atlantic Leatherback subpopulation nests only in southern Brazil (Thomé et al. 2007), and this rookery is genetically distinct from all other sampled rookeries in the Atlantic (Dutton et al. 2013). The marine habitat for this subpopulation is thought to extend north across the equator and east to the coast of Atlantic Africa, southwest to Uruguay and Argentina, and southeast to South African waters (see Figure 1 in Supplementary Material). However, the geographic boundaries for this subpopulation lack resolution.
Application of Criterion A2 is appropriate, as population reduction may have been observed in the past where the causes of reduction may not have ceased OR may not be understood OR may not be reversible. This subpopulation is increasing by 232%, and will increase by 957% in another generation (i.e., by 2040), with an abundance of approximately 169 nests (~34 females) per year, or approximately 85 adult females total.
We assessed the status of the Southwest Atlantic Leatherback subpopulation by Criteria A-D; as no population viability analysis has been performed, Criterion E could not be applied.
Leatherback age at maturity is uncertain, and estimates range widely (see Jones et al. 2011 for review). Reported estimates fall between 9-15 yr, based on skeletochronology (Zug and Parham 1996), and inferences from mark-recapture studies (Dutton et al. 2005). Furthermore, updated skeletochronological analyses estimated Leatherback age at maturity to be between 26-32 yr (mean 29 yr) (Avens et al. 2009). Extrapolations of captive growth curves under controlled thermal and trophic conditions suggested that size at maturity could be reached in 7-16 yr (Jones et al. 2011). Thus, a high degree of variance and uncertainty remains about Leatherback age at maturity in the wild. Likewise, Leatherback lifespan is unknown. Long-term monitoring studies of Leatherback nesting populations have tracked individual adult females over multiple decades (e.g. Santidrián Tomillo et al. unpublished data, Nel and Hughes unpublished data), but precise estimates of reproductive lifespan and longevity for Leatherbacks are currently unavailable.
Although monitoring of nesting activities by adult female sea turtles is the most common metric recorded and reported across sites and species, globally, there are several disadvantages to using it as a proxy for overall population dynamics, some methodological, some interpretive (NRC 2010). First, because nesting females are a very small proportion of a sea turtle population, using abundance of nesting females and their activities as proxies for overall population abundance and trends requires knowledge of other key demographic parameters (several mentioned below) to allow proper interpretation of cryptic trends in nesting abundance (NRC 2010). However, there remains great uncertainty about most of these fundamental demographic parameters for Leatherbacks, including age at maturity (see Jones et al. 2011 for review), generation length, survivorship across life stages, adult and hatchling sex ratios, and conversion factors among reproductive parameters (e.g., clutch frequency, nesting success, re-migration intervals, etc.). These values can vary among subpopulations, further complicating the process of combining subpopulation abundance and trend estimates to obtain global population abundance and trend estimates, and contributing to the uncertainty in these estimates. For example, in the present case of the Southwest Atlantic Leatherback subpopulation, our assumption of 3:1 female:male sex ratio has a significant impact on the estimate of mature individuals in the subpopulation; i.e. under the assumption of a 1:1 sex ratio, the number of mature individuals (n=54) would have exceeded the threshold for Critically Endangered, thus qualifying this subpopulation for the Endangered category. Our assumption was based on published data (Barata et al. 2004), but more information is needed to increase confidence in this assumption of adult sex ratios, as well as assumptions included in estimates of other demographic parameters.
Leatherbacks are distributed circumglobally, with nesting sites on subtropical and tropical sandy beaches and foraging ranges that extend into temperate and sub-polar latitudes. See Eckert et al. (2012) for review of Leatherback geographic range. The Southwest Atlantic Leatherback subpopulation nests only in Brazil (Thomé et al. 2007) and its marine habitat is thought to extend north across the equator in Brazil and east to the coast of Atlantic Africa, southwest to southern Brazil, Uruguay, and Argentina, and southeast to South African waters (see Figure 1 in Supplementary Material); however, the geographic boundaries for this subpopulation lack resolution.
Native:Angola; Argentina; Benin; Brazil; Cameroon; Congo; Congo, The Democratic Republic of the; Côte d'Ivoire; Equatorial Guinea; Gabon; Gambia; 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 Southwest Atlantic Ocean, Southeast 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, and in the Atlantic Ocean in particular (Dutton et al. 1999, 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:||Increasing|
|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|
|Movement patterns:||Full Migrant|
|Congregatory:||Congregatory (and dispersive)|
|Use and Trade:||Harvest of eggs has been minimized and human exploitation of females is non-existent.|
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 the Southwest Atlantic subpopulation, harvest of eggs has been minimized and human exploitation of females is non-existent, however, accidental capture in fisheries is one of the biggest threats (Pinedo and Polachek 2004, Domingo et al. 2006, Gallo et al. 2006, Lopez Mendilaharsu et al. 2007, Thomé et al. 2007, Bugoni et al. 2008, Fiedler et al. 2012, Wallace et al. 2013).
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, Riskas and Tiwari 2013, Wallace et al. 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).
Alfaro-Shigueto, J., Mangel, J.C., Bernedo, F., Dutton, P.H., Seminoff, J.A. and Godley, B.J. 2011. Small-scale fisheries of Peru: a major sink for marine turtles in the Pacific. Journal of Applied Ecology 48: 1432-1440.
Avens, L., Taylor, J.C., Goshe, L.R., Jones T.T. and Hastings, M. 2009. Use of skeletochronological analys to estimate the age of leatherback sea turtles Dermochelys coriacea in the western North Atlantic. Endangered Species Research 8: 165-177.
Bal, G., Breheret, N. and Vanleeuwe, H. 2007. An update on sea turtle conservation activities in the Republic of Congo. Marine Turtle Newsletter 116: 9-10.
Barata, P.C.R., Lima, E.H.S.M., Borges-Martins, M., Scalfoni, J.T., Bellini C. and Siciliano, S. 2004. Records of the leatherback sea turtle (Dermochelys coriacea) on the Brazilian coast, 1969-2001. Journal of the Marine Biological Association of the United Kingdom 84: 1233-1240.
Bellagio Report. 2007. Bellagio Sea Turtle Conservation Initiative: strategic planning for long-term financing of Pacific Leatherback conservation and recovery. Terengganu, Malaysia.
Blanc, J. 2008. African Elephant (Loxodonta africana). Available at: http://www.iucnredlist.org/details/12392/0. (Accessed: 21/09/2012).
Bugoni, L., Neves, T.S., Leite, N.O., Carvalho, D., Sales, G., Furness, R.W., Stein, C.E., Peppes, F.V., Giffoni, B.B. and Monteiro, D.S. 2008. Potential bycatch of seabirds and turtles in hook-and-line fisheries of the Itaipava Fleet, Brazil. Fisheries Research 90: 217-224.
Chacón-Chaverri, D. and Eckert, K.L. 2007. Leatherback sea turtle nesting at Gandoca Beach in Caribbean Costa Rica: management recommendations from fifteen years of conservation. Chelonian Conservation and Biology 6: 101-110.
Domingo, A., Bugoni, L., Prosdocimi, L., Miller, P., Laporta, M., Monteiro, D.S., Estrades, A. and Albareda, D. 2006. El impacto generado por las pesquerias en las tortugas marinas en el Océano Atlántico sud occidental. In: WWF Programa Marino para Latinoamérica y el Caribe (ed.). San Jose, Costa Rica.
Dutton, D.L., Dutton, P.H., Chaloupka, M. and Boulon, R.H. 2005. Increase of a Caribbean leatherback turtle Dermochelys coriacea nesting population linked to long-term nest protection. Biological Conservation 126: 186-204.
Dutton, P.H. and Squires, D. 2011. A holistic strategy for Pacific sea turtle conservation. In: P.H. Dutton, D. Squires and A. Mahfuzuddin (eds), Conservation and sustainable management of sea turtles in the Pacific Ocean, pp. 37-59. University of Hawaii Press, Honolulu, Hawaii.
Dutton, P.H., Roden, S.E., Stewart, K.R., LaCasella, E., Tiwari M., Formia A., Thomé J.C., Livingstone, S.R., Eckert, S., Chacón-Chaverri, D., Rivalan, P. and Allman, P. 2013. Population stock structure of leatherback turtles (Dermochelys coriacea) in the Atlantic revealed using mtDNA and microsatellite markers. Conservation Genetics 14(3): 625-636. DOI: 10.1007/s10592-013-0456-0.
Eckert, K.L., Wallace, B.P., Frazier, J.G., Eckert, S.A. and Pritchard, P.C.H. 2012. Synopsis of the biological data on the leatherback sea turtle (Dermochelys coriacea). U.S. Department of Interior, Fish and Wildlife Service, Biological Technical Publication BTP-R4015-2012. Washington, DC.
Fiedler, F.N., Sales, G., Giffoni, B., Monterio-Filho, E.L.A., Secchi, E.R. and Bugoni, L. 2012. Driftnet fishery threats to sea turtles in the Atlantic Ocean. Biodiversity and Conservation 21: 915-931.
Fretey, J., Billes A. and Tiwari, M. 2007. Leatherback, Dermochelys coriacea, nesting along the Atlantic coast of Africa. Chelonian Conservation and Biology 6: 126-129.
Gallo, B.M.G., Macedo, S., Giffoni, B.D.B., Becker, J.H. and Barata, P.C.R. 2006. Sea turtle conservation in Ubatuba, southeastern Brazil, a feeding area with incidental capture in coastal fisheries. Chelonian Conservation and Biology 6: 126-129.
Gilman, E., Gearhart, J., Price, B., Eckert, S., Milliken, H., Wang, J., Swimmer, Y., Shiode, D., Abe, O., Peckham, S.H., Chaloupka, M., Hall, M., Mangel, J., Alfaro-Shigueto. J., Dalzell, P. and Ishizaki, A. 2011. Mitigating sea turtle by-catch in coastal passive net fisheries. Fish and Fisheries 11(1): 57-88.
Gilman, E., Zollet, E., Beverley, S., Nkano, H., Davis, K., Shiode, D., Dalzell, P. and Kinan, I. 2006. Reducing sea turtle by-catch in pelagic longline fisheries. Fish and Fisheries 7: 2-23.
IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. IUCN, Gland, Switzerland and Cambridge, UK.
IUCN. 2013. IUCN Red List of Threatened Species (ver. 2013.2). Available at: http://www.iucnredlist.org. (Accessed: 13 November 2013).
IUCN Standards and Petitions Subcommittee. 2011. Guidelines for Using the IUCN Red List Categories and Criteria, Version 9.0 (September 2011). Available at: http://www.iucnredlist.org/documents/RedListGuidelines.pdf.
Jones, T.T., Hastings, M.D., Bostrom, B.L., Pauly, D.P. and Jones, D.R. 2011. Growth of captive leatherback turtles, Dermochelys coriacea, with inferences on growth in the wild: Implications for population decline and recovery. Journal of Experimental Marine Biology and Ecology 399: 84-92.
López-Mendilaharsu, M., Sales, G., Giffoni, B., Miller, P., Fiedler, F.N. and Domingo, A. 2007. Distribución y composición de tallas de las tortugas marinas (Caretta caretta y Dermochelys coriacea) que interactuan con el palangre pelagico en el Atlántico Sur. Collective Volume of Scientific Papers ICCAT 60(6): 2094-2109.
Mrosovsky, N. 2003. Predicting extinction: fundamental flaws in IUCN’s Red List system, exemplified by the case of sea turtles.
National Research Council (NRC) of the National Academies, USA. 2010. Assessment of sea turtle status and trends: Integrating demography and abundance. The National Academies Press. Washington, DC.
Pinedo, M.C. and Polachek, T. 2004. Sea turtle by-catch in pelagic longline sets off southern Brazil. Biological Conservation 119: 335-339.
Riskas, K.A. and Tiwari, M. 2013. An overview of fisheries and sea turtle bycatch along the Atlantic Coast of Africa. Munibe monographs, Nature series 1: 71-82.
Sarti Martínez, L., Barragán, A.R., Muñoz, D.G., García, N., Huerta, P. and Vargas F. 2007. Conservation and biology of the leatherback turtle in the Mexican Pacific. Chelonian Conservation and Biology 6: 70-78.
Seminoff, J.A. and Shanker, K. 2008. Marine turtles and IUCN Red Listing: A review of the process, the pitfalls, and novel assessment approaches. Journal of Experimental Marine Biology and Ecology 356: 52-68.
Spotila, J., Dunham, A., Leslie, A., Steyermark, A., Plotkin, P. and Paladino, F. 1996. Worldwide population decline of Dermochelys coriacea: are leatherback turtles going extinct? Chelonian Conservation Biology 2(2): 209-222.
Steering Committee, Bellagio Conference on Sea Turtles. 2004. What Can be Done to Restore Pacific Turtle Populations? The Bellagio Blueprint for Action on Pacific Sea Turtles. World Fish Center, Penang, Malaysia.
The State of the World’s Sea Turtles (SWOT) Scientific Advisory Board. 2011. Minimum Data Standards for Nesting Beach Monitoring. Technical Report.
Thome, J.C.A., Baptistotte, C., de P. Moreira, L.M., Scalfoni, J.T., Almeida, A.P., Rieth, D.B. and Barata, P.C.R. 2007. Nesting biology and conservation of the leatherback sea turtle (Dermochelys coriacea) in the state of Espirito Santo, Brazil, 1988-1989 to 2003-2004. Chelonian Conservation and Biology 6: 15-27.
Wallace, B.P., DiMatteo, A.D., Bolten, A.B., Chaloupka, M.Y., Hutchinson, B.J., Abreu-Grobois, F.A., Mortimer, J.A., Seminoff, J.A., Amorocho, D., Bjorndal, K.A., Bourjea, J., Bowen, B.W., Briseño-Dueñas, R., Casale, P., Choudhury, B.C., Costa, A., Dutton, P.H., Fallabrino, A., Finkbeiner, E.M., Girard, A., Girondot, M., Hamann, .M, Hurley, B.J., López-Mendilaharsu, M., Marcovaldi, M.A., Musick, J.A., Nel, R., Pilcher, N.J., Troëng, S., Witherington, B. and Mast, RB. 2011. Global conservation priorities for marine turtles. PLoS ONE 6(9): e24510. doi:10.1371/journal.pone.0024510.
Wallace, B.P., DiMatteo, A.D., Hurley, B.J., Finkbeiner, E.M., Bolten, A.B., Chaloupka, M.Y., Hutchinson, B.J., Abreu-Grobois, F.A., Amorocho, D., Bjorndal, K.A., Bourjea, J., Bowen, B.W., Briseño-Dueñas, R., Casale, P., Choudhury, B.C., Costa, A., Dutton, P.H., Fallabrino, A., Girard, A., Girondot, M., Godfrey, M.H., Hamann, M., López-Mendilaharsu, M., Marcovaldi, M.A., Mortimer, J.A., Musick, J.A., Nel, R., Pilcher, N.J., Seminoff, J.A., Troëng, S., Witherington, B. and Mast, R.B. 2010. Regional Management Units for marine turtles: A novel framework for prioritizing conservation and research across multiple scales. PLoS ONE 5(12): e15465. doi/10.1371/journal.pone.0015465.
Wallace, B.P., Kot, C.Y., DiMatteo, A.D., Lee, T., Crowder, L.B. and Lewison, R.L. 2013. Impacts of fisheries bycatch on marine turtle populations worldwide: toward conservation and research priorities. Ecosphere 4: 1-19. doi:10.1890/ES12-00388.1.
Watson, J.W., Epperly S.P., Shah A.K. and Foster D.G. 2005. Fishing methods to reduce sea turtle mortality associated with pelagic longlines. Canadian Journal of Fisheries and Aquatic Sciencies 62: 965-981.
Zug, G.R. and Parham, J.F. 1996. Age and growth in leatherback turtles, Dermochelys coriacea (Testudines: Dermochelyidae): A skeletochronological analysis. Chelonian Conservation and Biology 2(2): 244-249.
|Citation:||Tiwari, M., Wallace, B.P. & Girondot, M. 2013. Dermochelys coriacea (Southwest Atlantic Ocean subpopulation). The IUCN Red List of Threatened Species 2013: e.T46967838A46967842.Downloaded on 12 December 2017.|