| Taxon ID: 31,472 Total records: 39,143 | ||||||||||||||
Lepidochelys olivacea
Country
| Country | Myanmar |
|---|---|
| Continent Ocean | Asia |
Classification
| Kingdom | Animalia (COL) |
|---|---|
| Phylum | Chordata (COL) |
| Class | Reptilia (COL) |
| Order | Testudines (COL) |
| Family | Cheloniidae (COL) |
Taxonomy
| Genus | Lepidochelys | Reference | |
|---|---|---|---|
| SubGenus | Vernacular Name | ||
| Species | olivacea | IUCN Threat Status-Year | Vulnerable, 2008 |
| SubSpecies | Nat'l Threat Status-Year | Not Evaluated, 2000 | |
| Infraspecies | Reason for Change | ||
| Infraspecies Rank | CITES | ||
| Taxonomic Group | Reptiles | Native Status | Native |
| Scientific Name Author | Eschscholtz, 1829 | Country Distribution | Myanmar |
| Citation | Description | Geographic Range [top]
Range Description: The Olive Ridley sea turtle has a circumtropical distribution, with nesting occurring throughout tropical waters (except the Gulf of Mexico) and migratory circuits in tropical and some subtropical areas (Atlantic Ocean – eastern central, northeast, northwest, southeast, southwest, western central; Indian Ocean – eastern, western; Pacific Ocean – eastern central, northwest, southwest, western central) (Pritchard 1969). Nesting occurs in nearly 60 countries worldwide. Migratory movements are less well studied than other marine turtle species but are known to involve coastal waters of over 80 countries (see Table 1 in the Supplementary Material, see below). With very few exceptions they are not known to move between ocean basins or to cross from one ocean border to the other. Within a region, Olive Ridleys may move between the oceanic and neritic zones (Plotkin et al. 1995, Shanker et al. 2003) or just occupy neritic waters (Pritchard 1976, Reichart 1993).
For further information about this species, see 11534_Lepidochelys_olivacea.pdf.
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Countries occurrence:
Native:
Angola (Angola); Antigua and Barbuda; Australia; Bangladesh; Benin; Brazil; Brunei Darussalam; Cambodia; Cameroon; Cape Verde; Chile; Colombia; Congo; Costa Rica; Côte dIvoire; Cuba; Dominican Republic; Ecuador; El Salvador; Equatorial Guinea (Bioko); Eritrea; French Guiana; Gabon; Gambia; Ghana; Guadeloupe; Guatemala; Guinea; Guinea-Bissau; Guyana; Honduras; India (Andaman Is., Nicobar Is.); Indonesia; Iran, Islamic Republic of; Jamaica; Japan; Kenya; Liberia; Madagascar; Malaysia; Maldives; Martinique; Mauritania; Mexico; Micronesia, Federated States of ; Morocco; Mozambique; Myanmar; Namibia; Nicaragua; Nigeria; Oman; Pakistan; Panama; Papua New Guinea; Peru; Philippines; Puerto Rico; Sao Tomé and Principe (Sâo Tomé); Senegal; Sierra Leone; Somalia; South Africa; Sri Lanka; Sudan; Suriname; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Togo; Trinidad and Tobago; United States (Hawaiian Is.); Uruguay; Venezuela, Bolivarian Republic of (Venezuela (mainland), Venezuelan Antilles); Viet Nam; Yemen
FAO Marine Fishing Areas:
Native:
Atlantic – southeast; Atlantic – western central; Atlantic – eastern central; Atlantic – southwest; Indian Ocean – western; Indian Ocean – eastern; Pacific – western central; Pacific – southwest; Pacific – eastern central; Pacific – southeast
Additional data:
Range Map: Click here to open the map viewer and explore range.
Population [top]
Population:
For the purposes of Red List assessments, generation length is defined as the “average age of parents” (IUCN 2001). Since this information is not available from direct observation of sea turtle species we derived a comparable value from estimates of age at which 50% of the breeders are expected to have survived, using information for age at sexual maturity and adult survival rates. An important caveat is that, while it is known that different populations of the same species can attain sexual maturity at different ages (Heppell et al. 2003) and therefore different values would need to be taken into account for different regions, the information is only available for a single region and we have had to assume the estimated values are generally applicable on a global scale. The only published study on growth and age for Olive Ridleys (Zug et al. 2006) indicates a mean age at sexual maturity for North-central Pacific Ridley sea turtles of around 13 years (range of 10-18 years). We calculated the time it would take for a cohort of breeders to reach 50% of its original size from Sn =50%, where n is years since age at first reproduction, and S is annual survival. Solving for n, n = ln(0.5)/ln(S). As extensive estimates of annual survival rates for female nesters are only available from the better studied sister taxon, Lepidochelys kempii, (TEWG 2000) we used these, which have a range of 85-92% per year. Thus, n50% = 4-9 yrs and our derived average age of female Olive Ridley parents is 17-22 years. We additionally assumed that this value would be the same for male parents. For simplicity, we have used a value of 20 yrs for the species’ generation length in this assessment.
Current Population Trend: Decreasing
Additional data:
Habitat and Ecology [top]
Habitat and Ecology: Habitats
Like most other sea turtles, Olive Ridleys display a complex life cycle, which requires a range of geographically separated localities and multiple habitats (Márquez 1990). Females lay their nests on coastal sandy beaches from which neonates emerge and enter the marine environment to continue their development. They remain in a pelagic phase, drifting passively with major currents that disperse far from their natal sites, with juveniles sharing some of the adults’ habitats (Kopitsky et al. 2000) until sexual maturity is reached (Musick and Limpus 1997). Reproductively active males and females migrate toward coastal zones and concentrate near nesting beaches. However, some males appear to remain in oceanic waters and mate with females en route to their nesting beaches (Plotkin et al. 1996, Kopitsky et al. 2000). Their post-breeding migrations are complex, with pathways varying annually (Plotkin 1994) and with no apparent migratory corridors, swimming hundreds or thousands of kilometers over large ocean expanses (Morreale et al. 2007), commonly within the 20°C isotherms (Márquez 1990). In the East Pacific, they are present from 30°N to 15°S and often seen within 1,200 nautical miles from shore although they have been sighted as far as 140°W (IATTC 2004). Western Atlantic Olive Ridleys appear to remain in neritic waters after breeding (Pritchard 1976, Reichart 1993).
Demographic features / Reproduction
The species displays three modes of reproduction: arribada, dispersed nesting, and mixed strategy (Bernardo and Plotkin 2007). The first mode represents a synchronous, mass nesting behaviour that may include hundreds to thousands of females over a period of days and occurs in fewer than a dozen places worldwide. The more common form of nesting is dispersed or “solitary” with no apparent synchronicity between individual events. At some localities, a mixture of these two forms of nesting can also occur. In general, individual Olive Ridleys may nest one, two or three times per season, with approximately 100–110 eggs per clutch (Pritchard and Plotkin 1995). For this assessment we have used an average number of 2.5 nests/female/season and 105 eggs/nest. In contrast to other sea turtle species, the reproductive cycle is nearly annual (over 60% of turtles nest every year; Márquez 1990). Solitary nesters oviposit on 14 day cycles whereas arribada nesters approximately every 28 days (Pritchard 1969, Kalb and Owens 1994, Kalb 1999). Kalb (1999) found that within a nesting season solitary nesters use multiple beaches for oviposition but arribada nesters display nest site fidelity. There are extreme variations in hatching rates between nesting beaches, however, in general they are much higher in solitary nesting beaches where around 80% is common and sometimes even higher (Gaos et al. 2006). It is widely recognized that survivorship is extremely low on high-density arribada nesting beaches because of density-dependent mortality (Cornelius et al. 1991) leading to hatching rates as low as 1 to 8% (Cornelius et al. 1991). Moreover, turtles return approximately every month during a discrete nesting season (three to six months) and nests that remained intact during the previous month are again at risk when new waves of turtles crawl ashore. On solitary nesting beaches, where density-dependent mortality is not a factor, hatching rates are significantly higher (Castro 1986, Gaos et al. 2006). Post-hatching survivorship is unknown and there is no information available on recruitment rates. Presumably, like other sea turtles, Olive Ridleys experience high mortality in their early life stages. Juveniles are believed to occur in similar habitats as the adults (i.e,. pelagic waters) where they forage on gelatinous prey such as jellyfish, salps and tunicates (Kopitsky et al. 2004).
Systems: Terrestrial; Marine
Movement patterns: Full Migrant
Congregatory: Congregatory (and dispersive)
Threats [top]
Major Threat(s): Like other long-lived species, Olive Ridleys are prone to population declines because of slow intrinsic growth rate in combination with anthropogenic impacts. These can accumulate over a protracted development through various life stages, multiple habitats (nesting beaches, migratory routes and pelagic foraging zones) and vast geographic expanses.
Targeted exploitation
Egg harvest. Olive Ridleys and their eggs have been harvested, mostly unsustainably, worldwide. However, the current impact is difficult to evaluate because of other simultaneous factors such as incidental take in commercial fisheries. Nonetheless, there is documentation of recent egg use causing declines (Cornelius et al. 2007). From México to Colombia, Olive Ridley eggs have been and still are used for personal and commercial use (Lagueux 1989, Arauz 2000, Campbell 2007, Cornelius et al. 2007). Laws regulating turtle egg use vary among countries, and even where laws prohibit egg use, illegal use of Olive Ridley eggs is believed to be widespread because enforcement is either non-existent or insufficient. On unprotected solitary nesting beaches (most are unprotected), egg extraction often approaches 100%. Human use of turtle eggs for consumption and domestic animal consumption historically was widespread in the Indian Ocean and continues today largely wherever Ridleys nest (Cornelius et al. 2007). Egg use has been reported in India, Bangladesh, Myanmar, Sri Lanka, Andaman Islands, Pakistan and Malaysia and is believed to have caused the decline of Olive Ridleys in these countries (Cornelius et al. 2007). Even at monitored beaches a proportion of the eggs are still lost to poaching.
Directed take of adults. In the East Pacific, although Olive Ridley turtle fisheries are now closed, illegal take of adult turtles still occurs widely with an unknown level of impact. There is evidence that thousands of Olive Ridleys are still taken each year along the Pacific coast of México (Frazier et al. 2007). In the West Atlantic, the direct take of adults has diminished over time to negligible levels (Cornelius et al. 2007). In the Indian Ocean, the use of adult Olive Ridleys and their eggs for personal use has been and continues to be widespread (Frazier 1982, Frazier et al. 2007), and market-driven harvesting of eggs and females from nesting beaches are considered the greatest threat (Cornelius et al. 2007). Personal, subsistence use of adult Olive Ridley turtles is widespread worldwide (Cornelius et al. 2007, Frazier et al. 2007). Olive Ridleys and/or their eggs are used along the entire coast of West Africa (including Macaronesia) and sold in local and regional markets (Fretey 2001).
Bycatch in fisheries
The incidental capture of Olive Ridleys occurs worldwide in trawl fisheries, longline fisheries, purse seines, gill net and other net fisheries and hook and line fisheries (Frazier et al. 2007). The impact of the incidental capture of Olive Ridleys in fisheries has been well documented for some regions but not for others. In some locations where by-catch statistics are unavailable from fisheries, cause and effect has been used to implicate a fishery in the decline of Olive Ridleys. The incidental capture of Olive Ridleys in the shrimp trawl fishery in the western Atlantic, is believed to be the main cause of the significant population decline observed there since the 1970s and currently the number of Olive Ridleys by caught in trawl fisheries off the coasts of Surinam and French Guiana is believed to be approximately a couple of thousand turtles annually (Godfrey and Chevalier 2004, Frazier et al. 2007). Gillnets and other fishing methods in this region also capture Olive Ridleys incidentally but to a lesser extent than shrimp trawl fishery (Frazier et al. 2007). Bycatch in trawl fisheries off Sergipe State in Brazil is considered the most pressing threat to that population (Thomé et al. 2003). In the eastern Atlantic, the incidental capture of Olive Ridleys by commercial fisheries is thought to be a significant threat but very little systematic data is available (Frazier et al. 2007). Incidental mortality of Olive Ridleys is worst along the coast of Orissa, India with arribada Olive Ridleys gathering to nest were fishing effort is high. Every year since the early 1980s, thousands or tens of thousands of Olive Ridleys have stranded dead on the Orissa beaches, presumably as a result of incidental capture in shrimp trawls (Pandav 2000). A gill net fishery also operates in the region and contributes to the ridley mortality along this coastline. Incidental capture in fisheries is also believed to be a serious threat in the eastern Pacific (Frazier et al. 2007) where Olive Ridleys aggregate in large numbers off shore from nesting beaches (Kalb et al. 1995, Kalb 1999), but the information available is incomplete (Pritchard and Plotkin 1995, NMFS/USFWS 1998). Incidental capture of Olive Ridleys in this region has been documented in shrimp trawl fisheries, longline fisheries, purse seine fishery and gill net fisheries (Frazier et al. 2007). Incidental capture of sea turtles in shrimp trawls is a serious threat along the coast of Central America, with an estimated annual capture for all species of marine turtle exceeding 60,000 turtles, most of which are Olive Ridleys (Arauz 1996). Recent growth in the longline fisheries of this region are also a serious and growing threat to Olive Ridleys and have the potential to capture hundreds of thousands of Ridleys annually (Frazier et al., 2007). Bycatch of Olive Ridleys is high in Indonesian tuna long-lines and shrimp trawls although mortality appears to be low (WWF Indonesia, unpublished data).
Habitat impacts
Degradation, transformation and destruction of natural conditions at nesting beaches from coastal developments continue to threaten the long-term survival of many Olive Ridley rookeries. Transformation of nesting habitat comes from the construction of new aquaculture ponds, fishing harbours and tourist facilities, as well as growth of existing coastal villages which are increasing in many parts of the world within the range of the Olive Ridley, particularly along the east coast of India (Pandav and Choudhury 1999) and in some zones in coastal México to Central America (Cornelius et al. 2007). These impacts contribute stress directly through the loss of nesting habitat or indirectly through changes in the thermal profiles of the beach, increased light pollution (Witherington 1992) and sewage effluents.
Global warming has the potential to impact the habitats and ecosystems of Olive Ridley populations worldwide (Hays et al. 2003, Weishampal 2004) but the specific impacts are purely speculative at this time. Most accounts have focused on the impact of global warming on incubation temperatures of eggs, which influence the sex ratio of the embryos (Hays et al. 2003).
Diseases and predation
Extremely little is known about diseases and their effects on Olive Ridley abundance. The only disease identified in the literature for Olive Ridleys is fibropapilloma, a herpes-virus found in sea turtles nearly worldwide (Herbst 1994). The incidence of fibropapilloma is not believed to be high in Olive Ridleys but has been observed in Olive Ridleys nesting in Costa Rica (Herbst 1994) and in México (Vasconcelos et al. 2000). At some individual rookeries, the predation by wild pigs and/or feral dogs can be substantial (e.g., in the Andaman Islands; Andrews et al. 2001). Infestation of developing eggs by fly and beetle larvae can cause significant mortality of embryos. In an extremely worrying case, the beetle larvae (Omorgus suberosus fabricius) has become a plague in the world’s largest arribada rookery in Escobilla, México where it is provoking steep drops in the hatching efficiency of the clutches laid, from a typical 30% for this colony (Márquez 1990) to less than 5% in some areas (López-Reyes and Harfush 2000). When combined with the relatively low hatching rates of high-density arribada beaches and the destruction of eggs laid by previous nesters, this problem could provoke the rookery’s decline.
Conservation Actions [top]
Conservation Actions: Most of the conservation actions on behalf of the Olive Ridley at national and international levels have been based on the species’ listing under the Endangered category in the IUCN Red List. As an Appendix I species under CITES (Convention on International Trade in Endangered Species) the international trade of skins from the species, which fuelled the large scale commercial exploitation of the Olive Ridley from the 1960s into the 1980s was effectively halted. Other relevant international instruments that list the Olive Ridley as threatened and hence obligate its conservation by member states include: the Convention on Migratory Species (CMS) and the Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC). CMS-promoted Memoranda of Understanding for the conservation and management of marine turtles and their habitats have been signed by the Olive Ridley’s range states in the Indian Ocean and South East Asia (known as IOSEA) as well as in other regions such as the Atlantic Coast of Africa under the Memorandum of Understanding concerning Conservation Measures for Marine Turtles of the Atlantic Coast of Africa where 21 out of 26 range states participate.
On the basis of the species’ classification in the IUCN Red List or in national endangered species lists, local legislatures of range states confer protection to the Olive Ridley. Although this sanctions law-enforcement, the implementation remains patchy at the global scale because of paucity in enforcement capabilities. Successful conservation has usually relied on well-coordinated national programs in combination with local and non-governmental organizations incorporating public outreach. Statutory use and enforcement of the Turtle Excluder Devices in the shrimp trawlers has also proven critical in some areas with high levels of interaction with this fishery.
Despite the legislative efforts to protect the Olive Ridley, human impacts continue to be significant. In some areas (such as West Africa and South East Asia), extensive monitoring needs to be implemented to identify regions and stressors requiring priority actions. Bycatch and illegal take particularly from the coastal, artisanal fisheries need to be evaluated through adequate on-board observer programs and properly addressed. The beetle infestation of the Escobilla rookery must be adequately evaluated and acceptable measures of biological control of the insect need to be implemented. The impact from the increasing development of much of the range state’s coastline has to be evaluated and suitable mitigation measures implemented.
Citation: Abreu-Grobois, A & Plotkin, P. (IUCN SSC Marine Turtle Specialist Group). 2008. Lepidochelys olivacea. The IUCN Red List of Threatened Species 2008: e.T11534A3292503. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T11534A3292503.en. Downloaded on 28 July 2016.
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| Individual Count | 0 | GML Features | |
| Observerd Individual Count | 0 | Notes |
Collecting Event
Images
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Additional Info
Synonyms To Manage Synonyms for Lepidochelys olivacea, click this link: Synonyms. |
Caouana dessumierii Smith, 1849 ¦ Caouana olivacea Gray, 1844 ¦ Caouana ruppelli Gray, 1844 ¦ Caretta caretta Smith, 1931 ¦ Caretta olivacea Rüppell, 1835 ¦ Caretta remivaga Hay, 1908 ¦ Chelonia dussumierii Duméril & Bibron, 1835 ¦ Chelonia olivacea Eschscholtz, 1829 ¦ Chelonia subcarinata Rüppell In Gray, 1844 ¦ Lepidochelys dussumierii Girard, 1858 ¦ Lepidochelys olivacea Mertens & Wermuth, 1955 ¦ Thalssochelys olivacea Strauch, 1862 ¦ |
Common Names To Manage Common Names for Lepidochelys olivacea, click this link: Common Names. |
Olive Ridley Sea Turtle () ¦ Pacific Ridley () ¦ |
Localities To Manage Localities for Lepidochelys olivacea, click this link: Localities. |
Species Record Updated By:
Carlos Aurelio Callangan
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