A SUMMARY OF THE LEATHERBACK TURTLE RED LIST ASSESSMENTS IN THE INDIAN OCEAN

ANDREA D. PHILLOTT

Biological Sciences, Asian University for Women, Chittagong, Bangladesh

andrea.phillott@auw.edu.bd

Download article as PDF

A summary based on:
Tiwari, M., Wallace, B.P. & Girondot, M. 2013. Dermochelys coriacea (Northeast Indian Ocean subpopulation). In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. www.iucnredlist.org.

Wallace, B.P., Tiwari, M. & Girondot, M. 2013. Dermochelys coriacea. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. www.iucnredlist.org.

Wallace, B.P., Tiwari, M. & Girondot, M. 2013. Dermochelys coriacea (Southwest Indian Ocean subpopulation). In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. www.iucnredlist.org.

The appropriateness of global listings on the IUCN Red List of Threatened Species has long been debated by sea turtle biologists and conservationists (Groombridge & Luxmoore, 1989; Mrosovsky, 2003; Godfrey and Godley, 2008), with concerns that variations in population size and dynamics, geographic range, and subpopulation conservation status (including risk of extinction) were not adequately assessed. To address these concerns, the most recent Red List assessment for the leatherback turtle now includes both global and sub-population listings.

The global Red List status of leatherback turtles is ‘Vulnerable’, with fisheries by-catch posing the greatest threat. Other threats include human consumption of eggs and meat, and coastal development; there are insufficient data to gauge the threats posed by pollution and pathogens, and climate change to all subpopulations. The Southwest Indian Ocean, Southwest Atlantic, East Pacific and West Pacific subpopulations are listed as ‘Critically Endangered’, Northwest Atlantic populations as ‘Least Concern’, and Northeast Indian Ocean and Southeast Atlantic subpopulations as ‘Data Deficient’ (Wallace et al., 2013a).

Nearly 99% of the global leatherback population is expected to comprise turtles from the large, and increasing, Northwest Atlantic subpopulation by 2040. It is, therefore, essential that population growth of this subpopulation be sustained. However, conservation efforts to protect leatherback turtles and habitats in the Indian Ocean and other regions are equally as important in light of the significant threats to all subpopulations and the historical collapse of large Pacific subpopulations (Wallace et al., 2013a).

The Southwest Indian Ocean subpopulation of leatherback turtles in KwaZulu Natal, South Africa and Mozambique is small and geographically constrained. The size estimate is 148 adult turtles, with indications of a small but continuing decline (Wallace et al., 2013b). Major threats to the population include fisheries by-catch (Wallace et al., 2011; Nel, 2012), although this must be quantified, and harvest of eggs and meat in Mozambique (Nel, 2012). For further information on this leatherback subpopulation, see also Lombard and Kyle (2010), Nel (2010; 2012) and Nel et al. (2013).

The Northeast Indian Ocean subpopulation of the Andaman and Nicobar Islands, India, and Sri Lanka is listed as Data Deficient (Tiwari et al., 2013). A long term monitoring programme on Great Nicobar Island was terminated after the December 2004 tsunami (Andrews et al., 2006), and has been resumed on Little Andaman Island only since 2007 (Swaminathan et al., 2013). Consistent survey effort over more nesting seasons is required to determine population size and dynamics, and further surveys to measure geographic range. Similarly, insufficient information is available to identify and quantify major threats, although depredation of eggs is believed to be high. Published studies on these turtles include Andrews et al. (2006), Hamann et al. (2006), Namboothri et al. (2012), Swaminathan et al. (2011), Swaminathan et al. (2013) and Nel (2012).

In summary, the key knowledge gaps for leatherback turtles in the Indian Ocean include:

  1. Quantified mortality rates of fisheries by-catch.
  2. Continuous, long-term datasets with consistent monitoring for the Northeast Indian Ocean subpopulation.
  3. Knowledge of geographic boundaries of the Northeast Indian Ocean subpopulation.
  4. Estimates of leatherback egg and meat harvest and depredation

Literature cited

Andrews, H.V., S. Krishnan & P. Biswas. 2006. Distribution and status of marine turtles in the Andaman and Nicobar Islands. In: Marine Turtles of India (eds. Shanker, K. & B.C. Choudhury). Pp. 33-57. Hyderabad, India: Universities Press.

Godfrey, M.H. & B.J. Godley. 2008. Seeing past the red: Flawed IUCN listings for sea turtles. Endangered Species Research 6: 155-159.

Groombridge, B. & R.A. Luxmoore. 1989. The green turtle and hawksbill (Reptilia: Cheloniidae): world status, exploitation and trade. Lausanne, Switzerland: Secretariat of the Convention on International Trade in Endangered Species of Wild Fauna and Flora.

Hamann, M., C. Limpus, G.Hughes, J. Mortimer & N. Pilcher. 2006. Assessment of the conservation status of the leatherback turtle in the Indian Ocean and South-East Asia, including consideration of the impacts of the December 8 2004 tsunami on turtles and turtle habitats. IOSEA Marine Turtle MoU Secretariat, Bangkok, Thailand. Document available at www.ioseaturtles.org.

Lombard,P.&S.Kyle.2010.Marineturtlemonitoringand conservation in southern Mozambique. Project Report. Ezemvelo KZN Wildlife, KwaNgwanase, KwaZulu-Natal, South Africa.

Mrosovsky, N. 2003. Predicting extinction: fundamental flaws in IUCN’s Red List system, exemplified by the case of sea turtles. http://www.seaturtle.org/members/mrosovsky/ extinct.pdf. Accessed on 15th December 2013.

Namboothri, N., A. Swaminathan & K. Shanker. 2012. Post- nesting migratory routes of Leatherback Turtles from Little Andaman Island. Indian Ocean Turtle Newsletter 16: 21-23.

Nel, R. 2010. Sea turtles of KwaZulu-Natal: data report for 2007/8 season. Report prepared for Ezemvelo KwaZulu- Natal Wildlife. Available at www.ioseaturtles.org.

Nel, R. (compiler). 2012. Assessment of the conservation status of the leatherback turtle in the Indian Ocean and South-EastAsia.SecretariatoftheIndianOcean–South- EastAsianMarineTurtleMemorandumofUnderstanding. Bangkok, Thailand. Available at www.ioseaturtles.org.

Nel, R., A.E. Punt & G.R. Hughes. 2013. Are coastal protected areas always effective in achieving population recovery for nesting sea turtles? PLoS One 8: e63525.

Swaminathan, A., N. Namboothri & K. Shanker. 2011. Post- tsunami status of leatherback turtles on Little Andaman Island. Indian Ocean Turtle Newsletter 14: 5-9.

Swaminathan, A., N. Namboothri, M. Chandi & K. Shanker. 2013. Leatherback turtles at South Bay and West Bay, Little Andaman (2012-2013). Report submitted to the Andaman and Nicobar Forest Department. Indian Institute of Science, Dakshin Foundation and Andaman and Nicobar Environmental Team.

Tiwari, M., B.P. Wallace & M. Girondot. 2013. Dermochelys coriacea (Northeast Indian Ocean subpopulation). In: IUCN Red List of Threatened Species. Version 2013.2. Accessed at www.iucnredlist.org on 15th December 2013.

Wallace, B.P., A.D. DiMatteo, A.B. Bolten, M.Y. Chaloupka, B.J. Hutchinson, F.A. Abreu-Grobois, J.A. Mortimer et al. 2011. Global conservation priorities for marine turtles. PLoS One 6: e24510.

Wallace, B.P., M. Tiwari & M. Girondot. 2013a. Dermochelys coriacea. In: IUCN Red List of Threatened Species. Version 2013.2. Accessed at www.iucnredlist.org on 15th December 2013.

Wallace, B.P., M. Tiwari & M. Girondot. 2013b. Dermochelys coriacea (Southwest Indian Ocean subpopulation). In: IUCN Red List of Threatened Species. Version 2013.2. Accessed at www.iucnredlist.org on 15th December 2013.