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Conservation Status

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Within the past thirty years the Olive Ridley Turtle has experienced population loss due to hunting at nesting sites for the female's skin and meat. The Olive Ridley Turtle is still the most abundant of all sea turtles, yet it nests at only five beaches in the world. Governments are in the process of protecting these nesting sites and populations. The United States has passed a law requiring that all shrimp sold in the United States must be harvested by companies with "Turtle Excluder Devices" that allow sea turtles to safely escape capture in shrimping nets.

IUCN Red List of Threatened Species: vulnerable

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Herbst, P. 1999. "Lepidochelys olivacea" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lepidochelys_olivacea.html
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Benefits

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As with other large sea turtles, the Olive Ridley Sea Turtle is considered somewhat of a pest for commercial fishermen for they often find these turtles caught in their nets.

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Herbst, P. 1999. "Lepidochelys olivacea" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lepidochelys_olivacea.html
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Benefits

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Since turtle egg harvesting became legal on the Playa Ostional in Costa Rica in 1987, local villagers have been able to sell nearly 3 million eggs collected from the beaches each season. The villagers can legally harvest only eggs laid during the first 36 hours of a nesting period since any turtles nesting after this period would destroy them. Approximately 27 million eggs are left unharvested and are protected from predators such as snakes and birds by the villagers.

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Herbst, P. 1999. "Lepidochelys olivacea" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lepidochelys_olivacea.html
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Trophic Strategy

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The Olive Ridley is a chiefly carnivorous species feeding on invertebrates and protochordates such as jellyfish, snails, shrimp and crabs. The Olive Ridley Turtle has a tendency to eat a wide variety of foods which has lead to many attempts on its behalf to ingest trash such as plastic bags and Styrofoam. Surprisingly, in captivity, this species has been observed to be cannibalistic. Most feeding takes place in shallow, soft-bottomed waters. The Olive Ridley Turtle has also been known to principally feed on algae in areas devoid of other food sources.

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Herbst, P. 1999. "Lepidochelys olivacea" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lepidochelys_olivacea.html
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Distribution

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The Olive Ridley Turtle has a large range within the tropical and subtropical regions in the Pacific and Indian Oceans as well as the Southern Atlantic Ocean. They generally tend to stay within the latitudes of 40° North and 40° South. Around North America it can be found in the waters of the Caribbean Sea and along the Gulf of California. The largest nesting beach for the Olive Ridley Turtle is at the Bhitar Kanika Wildlife Sanctuary on the Bay of Bengal located in Orissa, India.

Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )

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Herbst, P. 1999. "Lepidochelys olivacea" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lepidochelys_olivacea.html
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Habitat

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The Olive Ridley Turtle spends most of its time within 15 km of shore, preferring shallow seas for is feeding and sunbathing. However this species is observed in the open ocean as well.

Aquatic Biomes: coastal

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Herbst, P. 1999. "Lepidochelys olivacea" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lepidochelys_olivacea.html
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Morphology

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The Olive Ridley Turtle is a large sea turtle that can weigh as much as 45 kg (100 lbs) and have a length of up to 75 cm (30 in). The skin of the turtle is olive gray and the distinguishing feature between male and female turtles is that the male's tail extends past the carapace while the female's does not. The relatively thin shell compared to other turtles is somewhat heart-shaped and is olive in color. Each of the four limbs has two claws.

Other Physical Features: ectothermic ; bilateral symmetry

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Herbst, P. 1999. "Lepidochelys olivacea" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lepidochelys_olivacea.html
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Reproduction

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While the exact age at which reproduction occurs is not known, females usually reach a length of 60 cm before becoming reproductively active. Mating usually occurs on beaches during the spring and early summer in North America and is not monogamous. Male sperm is stored within the female for use throughout the entire breeding season. Mating takes place just offshore of the breeding beaches. Females choose to return to their beach of birth and will do this by remembering the smell of the beach through enhanced chemosensors. Nesting takes place during the night with the females riding in on the high tide and usually coincides with the first or last quarter of the moon. The Olive Ridley turtle is well known for its mass nesting, with 300 or more females at a time coming ashore. Situating themselves approximately 50 m from the sea, females will dig a nest 30-55 cm deep, depositing on average 107 eggs, and then return to the sea. This entire process takes the female turtles less then an hour. Since females store sperm in their bodies for later use, a single female can nest multiple months in a row. The eggs resemble white ping-pong balls and hatch within 45-51 days depending on incubation temperatures, which will also determine the sex of the turtle. The turtles face varying degrees of success in each of the clutches that are laid in large groups to increase their success of surviving.

Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate)

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Herbst, P. 1999. "Lepidochelys olivacea" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lepidochelys_olivacea.html
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Biology

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Although they do also nest alone, olive ridleys are known for their remarkable mass nestings, when many thousands of females congregate on the same beach; the event is known as an 'arribada', which is Spanish for 'mass arrival' (5). Males and females migrate from the feeding grounds and mating occurs just offshore of the beach (9). Usually at night, and coinciding their nesting with the high tide, females haul out on their natal beach and lay clutches that typically contain around 110 to 120 eggs (9). These astonishing mass nestings can involve up to 150,000 females (7) and there may be more than one arribada on a single beach; this overcrowding means that turtles are often crawling over each other to move up the beach and may even unearth other nests whilst digging their own (5). During one season a female may lay two to three clutches of eggs, returning to breed every few years (9). After around 50 to 60 days, the hatchlings emerge and make their chaotic dash to the sea (5). Predators such as jackals and crabs will feed on turtle eggs, whilst birds attack hatchlings on the beach and fish wait in the shallows (9). These arribadas probably function to increase hatchling survival by overwhelming predators with sheer numbers (5). Adult olive ridleys are carnivorous and feed on a wide variety of organisms including fish and molluscs (5); sometimes diving up to 150 metres in search of prey (7). Very little is known about the first years of life but juveniles probably spend a number of years floating on the ocean currents and feeding on planktonic organisms (10).
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Conservation

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Numbers of marine turtles are notoriously difficult to investigate given their oceanic habitat and worldwide distribution. International trade in olive ridley turtles and products is banned under their listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) but a significant illegal trade (particularly in eggs) still occurs (5). TRAFFIC (the wildlife trade monitoring arm of WWF and the IUCN) is involved in monitoring black market trade and bringing it to the attention of relevant authorities (12). The fitting of Turtle Excluding Devices (TEDs) to shrimp-trawl nets offers an encouraging step in their conservation; a 'trap-door' in the net allows the large turtles to escape (10). Their use is still not widespread however, and even in countries where the use of TED's is mandatory, this is not enforced (9). A number of major nesting beaches are protected and conservation projects work to artificially rear turtle eggs and then release them. Recently the number of olive ridleys nesting in Mexico has increased (8), and arribadas have returned to the Gahirmatha rookery in Orissa, India (9); perhaps offering a glimmer of hope that conservation efforts are working.
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Description

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The olive ridley turtle is the smallest of the marine turtles (2). The carapace of this turtle is olive coloured and relatively heart-shaped, whilst the undersurface is a greenish white (6). It can be distinguished from the closely related Kemp's ridley turtle (Lepidochelys kempii) by the possession of more than five bony plates, or scutes, running the length of the carapace; Kemp's ridley has only five (6).
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Habitat

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The olive ridley turtle inhabits tropical waters, and adults are known to be pelagic, feeding in the open ocean (10). Nesting tends to occur on mainland shores, on wide beaches that are often close to river or estuary mouths (7).
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Range

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Found in tropical regions of the Indian, Pacific and Atlantic Oceans, excluding the Caribbean. The largest nesting colonies occur in Mexico, Costa Rica (7) and the Orissa coast, India (6).
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Status

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Classified as Vulnerable (VU) on the IUCN Red List (1). Listed on Appendix I of CITES (12) and Appendix I of the Convention on Migratory Species (CMS or Bonn Convention) (13).
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Threats

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Nesting in such large congregations, the olive ridley turtle is particularly vulnerable to human activities such as development and exploitation (5). This turtle has been extensively over-harvested for its eggs and meat; on the Mexican Pacific coast in the 1960s over one million individuals were killed each year (5). In Central and South America there is still a massive market for the now illegal turtle eggs, which are traditionally believed to have aphrodisiac properties (3). Artificial illumination from development poses an additional threat, and disorientates both adults and hatchlings on the nesting beaches (5). One of the most important threats to the olive ridley is incidental catch (bycatch) by the fishing industry; turtles caught in trawl nets drown and are then discarded (10). Between 1993 and 1999, more than 50,000 dead turtles were found along the Orissa coast in India, primarily as a direct result of illegal fishing in the area (11).
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Behaviour

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Mainly carnivorous, food items include various crustaceans, molluscs, jellyfish, and fish. Nesting often involves huge concentra­tions of females. Not known to nest in Egypt.

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Conservation Status

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Vulnerable  

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Description

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A moderately sized marine turtle; largest recorded specimen has a carapace length of 735 mm. Carapace depressed, slightly elongate, smooth; scutes juxtaposed; posterior edge with moderate indentations; with 6-8 coastal scutes; first marginal scute not in contact with first vertebral scute. Head large, triangular, with 2 pairs of prefrontals. Front limbs with a single claw, hind limbs with 2 claws. Males smaller, with longer tails and larger claws. Color of carapace and dorsal sides of limbs and head uniform olive gray. All ventral sides yellowish white.

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Distribution in Egypt

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Vagrant to Egyptian Red Sea waters, where it has been recorded at least three times, all in the 1970s, off the South Sinai coast. Two animals were caught in nets at Dahab and Nuweiba, and 2 animals were observed "off the southern tip of Sinai"

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Global Distribution

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Pan-tropical species, recorded about 5 times in the Red Sea. Nearest breeding site is on Masirah Island, Oman, where some 150 females nest annually.

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Habitat

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Warm tropical and subtropical marine waters, prefers shallow waters.

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Niger Coastal Delta Habitat

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The Niger Coastal Delta is an enormous classic distributary system located in West Africa, which stretches more than 300 kilometres wide and serves to capture most of the heavy silt load carried by the Niger River. The peak discharge at the mouth is around 21,800 cubic metres per second in mid-October. The Niger Delta coastal region is arguably the wettest place in Africa with an annual rainfall of over 4000 millimetres. Vertebrate species richness is relatively high in the Niger Delta, although vertebrate endemism is quite low. The Niger Delta swamp forests occupy the entire upper coastal delta. Historically the most important timber species of the inner delta was the Abura (Fleroya ledermannii), a Vulnerable swamp-loving West African tree, which has been reduced below populations viable for timber harvesting in the Niger Delta due to recent over-harvesting of this species as well as general habitat destruction of the delta due to the expanding human population here. Other plants prominent in the inner delta flood forest are: the Azobe tree (Lophira alata), the Okhuen tree (Ricinodendron heudelotii ), the Bitter Bark Tree (Sacoglottis gabonensis), the Rough-barked Flat-top Tree (Albizia adianthifolia), and Pycnanthus angolensis. Also present in its native range is the African Oil Palm (Elaeis guineensis)

Five threatened marine turtle species are found in the mangroves of the lower coastal delta: Leatherback Sea Turtle (Dermochelys coricea, EN), Loggerhead Sea Turtle (Caretta caretta, EN), Olive Ridley Turtle (Lepidochelys olivacea, EN), Hawksbill Sea Turtle (Eretmochelys imbricata, CR), and Green Turtle (Chelonia mydas, EN).

There are a number of notable mammals present in the upper (or inner) coastal delta in addition to the Critically Endangered Niger Delta Red Colubus (Procolobus pennantii ssp. epieni), which primate is endemic to the Niger Delta. The near-endemic White-cheeked Guenon (Cercopithecus erythrogaster, VU) is found in the inner delta. The Endangered Chimpanzee (Pan troglodytes) is also found in the inner delta. The limited range Black Duiker (Cephalophus niger) is fournd in the inner delta and is a near-endemic to the Niger River Basin. The restricted distribution Mona Monkey (Cercopithecus mona), a primate often associated with rivers, is found here in the Niger Delta. The Near Threatened Olive Colobus (Procolobus verus) is restricted to coastal forests of West Africa and is found here in the upper delta.

Some of the reptiles found in the upper Coastal Niger Delta are the African Banded Snake (Chamaelycus fasciatus); the West African Dwarf Crocodile (Osteolaemus tetraspis, VU); the African Slender-snouted Crocodile (Mecistops cataphractus); the Benin Agama (Agama gracilimembris); the Owen's Chameleon (Chamaeleo oweni); the limited range Marsh Snake (Natriciteres fuliginoides); the rather widely distributed Black-line Green Snake (Hapsidophrys lineatus); Cross's Beaked Snake (Rhinotyphlops crossii), an endemic to the Niger Basin as a whole; Morquard's File Snake (Mehelya guirali); the Dull Purple-glossed Snake (Amblyodipsas unicolor); the Rhinoceros Viper (Bitis nasicornis). In addition several of the reptiles found in the outer delta are found within this inner delta area.

Other reptiles found in the outer NIger Delta are the Nile Crocodile (Crocodylus niloticus), African Softshell Turtle (Trionyx triunguis), African Rock Python (Python sebae), Boomslang Snake (Dispholidus typus), Cabinda Lidless Skink (Panaspis cabindae), Neon Blue Tailed Tree Lizard (Holaspis guentheri), Fischer's Dwarf Gecko (Lygodactylus fischeri), Richardson's Leaf-Toed Gecko (Hemidactylus richardsonii), Spotted Night Adder (Causus maculatus), Tholloni's African Water Snake (Grayia tholloni), Smith's African Water Snake (Grayia smythii), Small-eyed File Snake (Mehelya stenophthalmus), Western Forest File Snake (Mehelya poensis), Western Crowned Snake (Meizodon coronatus), Western Green Snake (Philothamnus irregularis), Variable Green Snake (Philothamnus heterodermus), Slender Burrowing Asp (Atractaspis aterrima), Forest Cobra (Naja melanoleuca), Rough-scaled Bush Viper (Atheris squamigera), and Nile Monitor (Varanus niloticus).

There are a limited number of amphibians in the inner coastal delta including the Marble-legged Frog (Hylarana galamensis). At the extreme eastern edge of the upper delta is a part of the lower Niger and Cross River watersheds that drains the Cross-Sanaka Bioko coastal forests, where the near endemic anuran Cameroon Slippery Frog (Conraua robusta) occurs.

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Distribution

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Continent: Africa Near-East North-America Middle-America Asia Caribbean South-America Australia
Distribution: Pacific and Indian oceans from Micronesia, Japan, India, and Arabia south to S Africa; Israel, Eritrea, United Arab Emirates (UAE), Somalia, Madagascar, Seychelles, Andaman Islands, Nicobar Islands, Cameroon Atlantic Ocean off the western coast of Africa; e.g. Gabon; Mauritania, Tanzania, Zanzibar, Principé and São Tomé (Gulf of Guinea), Gambia Australia (North Territory, Queensland, West Australia), Solomon Islands [McCoy 2000], In the eastern Pacific it is found from the Galapagos northward to the USA (Alaska, California, Oregon ?, Washington); Occasionally in the Caribbean Sea as far north as Puerto Rico. Central America: SE Mexico, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, Panama South America: coasts of N Brazil, French Guiana, Surinam, Guyana, Venezuela acording to the 1994 IUCN Red List of Threatened Animals: EC/SE/SW/WC Atlantic Ocean, Indian Ocean, EC-SE-SW-WC Pacific Ocean, Angola, Australia, Bangladesh, Brazil, Costa Rica, El Salvador, French Guiana, Guatemala, Guyana, Honduras, India, Indonesia, Kenya, Madagascar, Malaysia, Mexico, Mozambique, Myanmar (= Burma), Nicaragua, Oman, Pakistan, Panama, Papua New Guinea, Peru, Senegal, South Africa, Sri Lanka, Suriname, Tanzania, Thailand, Trinidad and Tobago, Venezuela
Type locality: Manila Bay, Philippines (fide COGGER 1983).
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Comprehensive Description

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Caretta remivaga Hay, 1908

[= Lepidochelys olivacea (Eschscholtz, 1829); fide, Schmidt, 1953:107, Zug et al., 1998:653.1]

Hay, 1908, Proc. U.S. Natl. Mus. 34(1605):194, pl. 10: figs. 1–3; pl. 11: fig. 5.

Holotype: USNM 243393 (formerly USNM Osteo 9973), adult skull and mandible, sex unknown, CBL 144 mm; collected by Francois Sumichrast, date unknown; recataloged Apr–Jun 1984 (see “Remarks”).

Type Locality: “Ventosa Bay, Mexico” [Bahia Ventosa in the Gulf of Tehuantepec, Oaxaca, Mexico].

Paratype: USNM 220820 (formerly USNM Osteo 29354) (adult skull, sex unknown, CBL 141 mm); locality, collector, and date unknown; originally cataloged 1 Dec 1893, recataloged May–June 1981.

Etymology: The name remivaga is from the Latin remigulus, a rower, and vago, to wander, in reference to the wide range of this species.

Remarks: The holotype was received in 1870 and incorrectly numbered USNM Osteo 8073 by staff of the former Division of Comparative Anatomy; that number was originally assigned to a Brown-headed Cowbird (Molothrus ater) in 1868. Subsequently the specimen number was corrected to USNM Osteo 9973 in the former Division of Comparative Anatomy and so listed by Cochran (1961:227).
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Reynolds, Robert P., Gotte, Steve W., and Ernst, Carl H. 2007. "Catalogue of Type Specimens of Recent Crocodilia and Testudines in the National Museum of Natural History, Smithsonian Institution." Smithsonian Contributions to Zoology. 1-49. https://doi.org/10.5479/si.00810282.626

Olive ridley sea turtle

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The olive ridley sea turtle (Lepidochelys olivacea), also known commonly as the Pacific ridley sea turtle, is a species of turtle in the family Cheloniidae. The species is the second-smallest[4][5] and most abundant of all sea turtles found in the world. L. olivacea is found in warm and tropical waters, primarily in the Pacific and Indian Oceans, but also in the warm waters of the Atlantic Ocean.[6]

This turtle and the related Kemp's ridley turtle are best known for their unique synchronised mass nestings called arribadas, where thousands of females come together on the same beach to lay eggs.[4][5]

Taxonomy

The olive ridley sea turtle may have been first described as Testudo mydas minor by Georg Adolf Suckow in 1798. It was later described and named Chelonia multiscutata by Heinrich Kuhl in 1820. Still later, it was described and named Chelonia olivacea by Johann Friedrich von Eschscholtz in 1829. The species was placed in the subgenus Lepidochelys by Leopold Fitzinger in 1843.[7] After Lepidochelys was elevated to full genus status, the species was called Lepidochelys olivacea by Charles Frédéric Girard in 1858. Because Eschscholtz was the first to propose the specific epithet olivacea, he is credited as the binomial authority or taxon author in the valid name Lepidochelys olivacea (Eschscholtz, 1829). The parentheses indicate that the species was originally described in a different genus.

The generic name, Lepidochelys, is derived from the Greek words lepidos, meaning scale, and chelys, which translates to turtle. This could possibly be a reference to the supernumerary costal scutes characteristic of this genus.[8] The etymology of the English vernacular name "olive" is somewhat easier to resolve, as its carapace is olive green in color.[9] However, the origin of "ridley" is still somewhat unclear, perhaps derived from "riddle".[10] Lepidochelys is the only genus of sea turtles containing more than one extant species: L. olivacea and the closely related L. kempii (Kemp's ridley).[11]

Description

Growing to about 61 cm (2 ft) in carapace length (measured along the curve), the olive ridley sea turtle gets its common name from its olive-colored carapace, which is heart-shaped and rounded. Males and females grow to the same size, but females have a slightly more rounded carapace as compared to males.[6] The heart-shaped carapace is characterized by four pairs of pore-bearing inframarginal scutes on the bridge, two pairs of prefrontals, and up to nine lateral scutes per side. L. olivacea is unique in that it can have variable and asymmetrical lateral scute counts, ranging from five to nine plates on each side, with six to eight being most commonly observed.[8] Each side of the carapace has 12–14 marginal scutes.

The carapace is flattened dorsally and highest anterior to the bridge. it has a medium-sized, broad head that appears triangular from above. The head's concave sides are most obvious on the upper part of the short snout. It has paddle-like fore limbs, each having two anterior claws. The upper parts are grayish-green to olive in color, but sometimes appear reddish due to algae growing on the carapace. The bridge and hingeless plastron of an adult vary from greenish white in younger individuals to a creamy yellow in older specimens (maximum age is up to 50 years).[8][12]

Hatchlings are dark gray with a pale yolk scar, but appear all black when wet.[8] Carapace length of hatchlings ranges from 37 to 50 mm (1.5 to 2.0 in). A thin, white line borders the carapace, as well as the trailing edge of the fore and hind flippers.[12] Both hatchlings and juveniles have serrated posterior marginal scutes, which become smooth with age. Juveniles also have three dorsal keels; the central longitudinal keel gives younger turtles a serrated profile, which remains until sexual maturity is reached.[8]

The olive ridley sea turtle rarely weighs over 50 kg (110 lb). Adults studied in Oaxaca, Mexico,[8] ranged from 25 to 46 kg (55 to 101 lb); adult females weighed an average of 35.45 kg (78.2 lb) (n=58), while adult males weighed significantly less, averaging 33.00 kg (72.75 lb) (n=17). Hatchlings usually weigh between 12.0 and 23.3 g (0.42 and 0.82 oz).

Adults are sexually dimorphic. The mature male has a longer and thicker tail, which is used for copulation,[8] and the presence of enlarged and hooked claws on the male's front flippers allows him to grasp the female's carapace during copulation. The male also has a longer, more tapered carapace than the female, which has a rounded, dome-like carapace.[8] The male also has a more concave plastron, believed to be another adaptation for mating. The plastron of the male may also be softer than that of the female.[12]

Distribution

 src=
L. olivacea distribution map: Red circles are major nesting grounds; yellow circles are minor nesting beaches.

The olive ridley turtle has a circumtropical distribution, living in tropical and warm waters of the Pacific and Indian Oceans from India, Arabia, Japan, and Micronesia south to southern Africa, Australia, and New Zealand. In the Atlantic Ocean, it has been observed off the western coast of Africa and the coasts of northern Brazil, Suriname, Guyana, French Guiana, and Venezuela. Additionally, the olive ridley has been recorded in the Caribbean Sea as far north as Puerto Rico. A female was found alive on an Irish Sea beach on the Isle of Anglesey, Wales, in November 2016, giving this species its northernmost appearance. It was taken in by the nearby Anglesey Sea Zoo, while its health was assessed.[13] A juvenile female was found off the coast of Sussex in 2020.[14] The olive ridley is also found in the eastern Pacific Ocean from the Galápagos Islands and Chile north to the Gulf of California, and along the Pacific coast to at least Oregon. Migratory movements have been studied less intensely in olive ridleys than other species of marine turtles, but they are believed to use the coastal waters of over 80 countries.[15] Historically, this species has been widely regarded as the most abundant sea turtle in the world.[8] More than one million olive ridleys were commercially harvested off the coasts of Mexico in 1968 alone.[16]

The population of Pacific Mexico was estimated to be at least 10 million prior to the era of mass exploitation. More recently, the global population of annual nesting females has been reduced to about two million by 2004,[17] and was further reduced to 852,550 by 2008.[1][18] This indicated a dramatic decrease of 28 to 32% in the global population within only one generation (i.e., 20 years).[15]

Olive ridley sea turtles are considered the most abundant, yet globally they have declined by more than 30% from historic levels. These turtles are considered endangered because of their few remaining nesting sites in the world. The eastern Pacific turtles have been found to range from Baja California, Mexico, to Chile. Pacific olive ridleys nest around Costa Rica, Mexico, Nicaragua, and the northern Indian Ocean; the breeding colony in Mexico was listed as endangered in the US on July 28, 1978.[19]

Nesting grounds

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Olive ridley hatchling
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Nesting

Olive ridley turtles exhibit two different nesting behaviours, the most prevalent solitary nesting, but also the behaviour they are best known for, the synchronized mass nesting, termed arribadas.[12] Females return to the same beach from where they hatched, to lay their eggs. They lay their eggs in conical nests about 1.5 ft deep, which they laboriously dig with their hind flippers.[6] In the Indian Ocean, the majority of olive ridleys nest in two or three large assemblies near Gahirmatha in Odisha. The coast of Odisha in India is one of the largest mass nesting sites for the olive ridley, along with the coasts of Mexico and Costa Rica.[6] In 1991, over 600,000 turtles nested along the coast of Odisha in one week. Solitary nesting also occurs along the Coromandel Coast and Sri Lanka, but in scattered locations. However, olive ridleys are considered a rarity in most areas of the Indian Ocean.[18]

They are also rare in the western and central Pacific, with known arribadas occurring only within the tropical eastern Pacific, in Central America and Mexico. In Costa Rica, they occur at Nancite and Ostional beach, and a third arribada beach seems to be emerging at Corozalito. Two active arribada beaches are located in Nicaragua, Chacocente and La Flor, with a smaller arribada beach of unknown status on the Pacific coast of Panama. Historically, arribadas happened at several beaches in Mexico, but in the present arribadas are only observed at Playa Escobilla and Morro Ayuda in Oaxaca, and Ixtapilla in Michoacan.[18]

Although olive ridleys are famed for their arribadas, most of the known nesting beaches are only frequented by solitarily nesting females and support a relatively small quantity of nests (100 to 3,000 nests). The overall contribution and importance of solitary nesting females for the population may be underestimated by the scientific community as the hatching success rate of nests at arribada beaches is generally low, but high at solitary nesting beaches.[8]

Isolated nesting does also sporadically occur.[20]

Foraging grounds

Some of the olive ridley's foraging grounds near Southern California are contaminated due to sewage, agricultural runoff, pesticides, solvents, and industrial discharges. These contaminants have been shown to decrease the productivity of the benthic community, which negatively affects these turtles, which feed from these communities.[8] The increasing demand to build marinas and docks near Baja California and Southern California are also negatively affecting the olive ridleys in these areas, where more oil and gasoline will be released into these sensitive habitats. Another threat to these turtles is power plants, which have documented juvenile and subadult turtles becoming entrained and entrapped within the saltwater cooling intake systems.[8]

Ecology and behavior

Photo of rear of turtle on beach with three white, round eggs lying behind it in a small hole in the sand
An olive ridley sea turtle laying eggs

Reproduction

Mating is often assumed to occur in the vicinity of nesting beaches, but copulating pairs have been reported over 1,000 km from the nearest beach. Research from Costa Rica revealed the number of copulating pairs observed near the beach could not be responsible for the fertilization of the tens of thousands of gravid females, so a significant amount of mating is believed to have occurred elsewhere at other times of the year.[8]

The Gahirmatha Beach in Kendrapara district of Odisha (India), which is now a part of the Bhitarkanika Wildlife Sanctuary, is the largest breeding ground for these turtles. The Gahirmatha Marine Wildlife Sanctuary, which bounds the Bhitarkanika Wildlife Sanctuary to the east, was created in September 1997, and encompasses Gahirmatha Beach and an adjacent portion of the Bay of Bengal. Bhitarkanika mangroves were designated a Ramsar Wetland of International Importance in 2002. It is the world's largest known rookery of olive ridley sea turtles. Apart from Gahirmatha rookery, two other mass nesting beaches have been located, which are on the mouth of rivers Rushikulya and Devi. The spectacular site of mass congregation of olive ridley sea turtles for mating and nesting enthralls both the scientists and the nature lovers throughout the world.

Olive ridley sea turtles migrate in huge numbers from the beginning of November, every year, for mating and nesting along the coast of Orissa. Gahirmatha coast has the annual nesting figure between 100,000 and 500,000 each year. A decline in the population of these turtles has occurred in the recent past due to mass mortality. The olive ridley sea turtle has been listed on Schedule – I of the Indian Wildlife (Protection) Act, 1972 (amended 1991). The species is listed as vulnerable under IUCN.[1] The sea turtles are protected under the 'Migratory Species Convention' and Convention of International Trade on Wildlife Flora and Fauna (CITES). India is a signatory nation to all these conventions. The homing characteristics of the ridley sea turtles make them more prone to mass casualty. The voyage to the natal nesting beaches is the dooming factor for them. Since Gahirmatha coast serves as the natal nesting beach for millions of turtles, it has immense importance on turtle conservation.

Olive ridleys generally begin to aggregate near nesting beaches about two months before nesting season, although this may vary throughout their range. In the eastern Pacific, nesting occurs throughout the year, with peak nesting events (arribadas) occurring between September and December. Nesting beaches can be characterized as relatively flat, midbeach zone, and free of debris.[7] Beach fidelity is common, but not absolute. Nesting events are usually nocturnal, but diurnal nesting has been reported, especially during large arribadas.[8] Exact age of sexual maturity is unknown, but this can be somewhat inferred from data on minimum breeding size. For example, the average carapace length of nesting females (n = 251) at Playa Nancite, Costa Rica, was determined to be 63.3 cm, with the smallest recorded at 54.0 cm.[8] Females can lay up to three clutches per season, but most only lay one or two clutches.[12] The female remains near shore for the internesting period, which is about one month. Mean clutch size varies throughout its range and decreases with each nesting attempt.[18]

A mean clutch size of 116 (30–168 eggs) was observed in Suriname, while nesting females from the eastern Pacific were found to have an average of 105 (74–126 eggs).[12] The incubation period is usually between 45 and 51 days under natural conditions, but may extend to 70 days in poor weather conditions. Eggs incubated at temperatures of 31 to 32 °C produce only females; eggs incubated at 28 °C or less produce solely males; and incubation temperatures of 29 to 30 °C produce a mixed-sex clutch.[12] Hatching success can vary by beach and year, due to changing environmental conditions and rates of nest predation.

Habitat

Most observations are typically within 15 km of mainland shores in protected, relatively shallow marine waters (22–55 m deep).[12] Olive ridleys are occasionally found in open waters. The multiple habitats and geographical localities used by this species vary throughout its lifecycle.[7]

Feeding

The olive ridley is predominantly carnivorous, especially in immature stages of its lifecycle.[21] Animal prey consists of protochordates or invertebrates, which can be caught in shallow marine waters or estuarine habitats. Common prey items include jellyfish, tunicates, sea urchins, bryozoans, bivalves, snails, shrimp, crabs, rock lobsters, and sipunculid worms. Additionally, consumption of jellyfish and both adult fish (e.g. Sphoeroides) and fish eggs may be indicative of pelagic (open ocean) feeding.[12] The olive ridley is also known to feed on filamentous algae in areas devoid of other food sources. Captive studies have indicated some level of cannibalistic behavior in this species.[8]

Threats

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Olive ridley entangled in a ghost net within the Maldives
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Taken in a drifting net in the Maldives
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Floating in the Arabian Sea, possibly killed by a boat propeller
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Dead olive ridley washed ashore and bloated with decomposition gases at Gahirmatha beach, Odisha, India
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Hatchlings in Chennai

Known predators of olive ridley eggs include raccoons, coyotes, feral dogs and pigs, opossums, coatimundi, caimans, ghost crabs, and the sunbeam snake.[12] Hatchlings are preyed upon as they travel across the beach to the water by vultures, frigate birds, crabs, raccoons, coyotes, iguanas, and snakes. In the water, hatchling predators most likely include oceanic fishes, sharks, and crocodiles. Adults have relatively few known predators, other than sharks, and killer whales are responsible for occasional attacks. On land, nesting females may be attacked by jaguars. Notably, the jaguar is the only cat with a strong enough bite to penetrate a sea turtle's shell, thought to be an evolutionary adaption from the Holocene extinction event. In observations of jaguar attacks, the cats consumed the neck muscles of the turtle and occasionally the flippers, but left the remainder of the turtle carcass for scavengers as most likely, despite the strength of its jaws, a jaguar still cannot easily penetrate an adult turtle's shell to reach the internal organs or other muscles. In recent years, increased predation on turtles by jaguars has been noted, perhaps due to habitat loss and fewer alternative food sources. Sea turtles are comparatively defenseless in this situation, as they cannot pull their heads into their shells like freshwater and terrestrial turtles.[8][22] Females are often plagued by mosquitos during nesting. Humans are still listed as the leading threat to L. olivacea, responsible for unsustainable egg collection, slaughtering nesting females on the beach, and direct harvesting adults at sea for commercial sale of both the meat and hides.[12]

Other major threats include mortality associated with boat collisions, and incidental takes in fisheries. Trawling, gill nets, ghost nests, longline fishing, and pot fishing have significantly affected olive ridley populations, as well as other species of marine turtles.[1][8] Between 1993 and 2003, more than 100,000 olive ridley turtles were reported dead in Odisha, India from fishery-related practices.[23] In addition, entanglement and ingestion of marine debris is listed as a major threat for this species. Coastal development, natural disasters, climate change, and other sources of beach erosion have also been cited as potential threats to nesting grounds.[8] Additionally, coastal development also threatens newly hatched turtles through the effects of light pollution.[24] Hatchlings which use light cues to orient themselves to the sea are now misled into moving towards land, and die from dehydration or exhaustion, or are killed on roads.

The greatest single cause of olive ridley egg loss, though, results from arribadas, in which the density of nesting females is so high, previously laid nests are inadvertently dug up and destroyed by other nesting females.[8] In some cases, nests become cross-contaminated by bacteria or pathogens of rotting nests. For example, in Playa Nancite, Costa Rica, only 0.2% of the 11.5 million eggs produced in a single arribada successfully hatched. Although some of this loss resulted from predation and high tides, the majority was attributed to conspecifics unintentionally destroying existing nests. The extent to which arribadas contribute to the population status of olive ridleys has created debate among scientists. Many believe the massive reproductive output of these nesting events is critical to maintaining populations, while others maintain the traditional arribada beaches fall far short of their reproductive potential and are most likely not sustaining population levels.[8] In some areas, this debate eventually led to legalizing egg collection.

Economic importance

Historically, the olive ridley has been exploited for food, bait, oil, leather, and fertilizer. The meat is not considered a delicacy; the egg, however, is esteemed everywhere. Egg collection is illegal in most of the countries where olive ridleys nest, but these laws are rarely enforced. Harvesting eggs has the potential to contribute to local economies, so the unique practice of allowing a sustainable (legal) egg harvest has been attempted in several localities.[18] Numerous case studies have been conducted in regions of arribadas beaches to investigate and understand the socioeconomic, cultural, and political issues of egg collection. Of these, the legal egg harvest at Ostional, Costa Rica, has been viewed by many as both biologically sustainable and economically viable. Since egg collection became legal in 1987, local villagers have been able to harvest and sell around three million eggs annually. They are permitted to collect eggs during the first 36 hours of the nesting period, as many of these eggs would be destroyed by later nesting females. Over 27 million eggs are left unharvested, and villagers have played a large role in protecting these nests from predators, thereby increasing hatching success.[8]

Most participating households reported egg harvesting as their most important activity, and profits earned were superior to other forms of available employment, other than tourism. The price of Ostional eggs was intentionally kept low to discourage illegal collection of eggs from other beaches. The Ostional project retained more local profits than similar egg-collection projects in Nicaragua,[18] but evaluating egg-harvesting projects such as this suffers from the short timeline and site specificity of findings. In most regions, illegal poaching of eggs is considered a major threat to olive ridley populations, thus the practice of allowing legal egg harvests continues to attract criticism from conservationists and sea turtle biologists. Plotkin's Biology and Conservation of Ridley Sea Turtles, particularly the chapter by Lisa Campbell titled "Understanding Human Use of Olive Ridleys", provides further research on the Ostional harvest (as well as other harvesting projects). Scott Drucker's documentary, Between the Harvest, offers a glimpse into this world and the debate surrounding it.

Conservation status

Photo of two small turtles crawling on beach
Two olive ridley hatchlings moving into the ocean after being released from a conservation site in Puerto Vallarta, Mexico.

The olive ridley is classified as vulnerable according to the International Union for Conservation of Nature and Natural Resources, and is listed in Appendix I of CITES. These listings were largely responsible for halting the large-scale commercial exploitation and trade of olive ridley skins.[1] The Convention on Migratory Species and the Inter-American Convention for the Protection and Conservation of Sea Turtles have also provided olive ridleys with protection, leading to increased conservation and management for this marine turtle. National listings for this species range from endangered to threatened, yet enforcing these sanctions on a global scale has been unsuccessful for the most part. Conservation successes for the olive ridley have relied on well-coordinated national programs in combination with local communities and nongovernment organizations, which focused primarily on public outreach and education. Arribada management has also played a critical role in conserving olive ridleys.[18] Lastly, enforcing the use of turtle excluder devices in the shrimp-trawling industry has also proved effective in some areas.[1] Globally, the olive ridley continues to receive less conservation attention than its close relative, Kemp's ridley (L. kempii). Also, many schools arrange trips for students to carry out the conservation project, especially in India.

Several projects worldwide seek to preserve the olive ridley sea turtle population. For example, in Nuevo Vallarta, Mexico, when the turtles come to the beach to lay their eggs, some of them are relocated to a hatchery, where they have a much better chance to survive. If the eggs were left on the beach, they would face many threats such as getting washed away with the tide or being poached. Once the eggs hatch, the baby turtles are carried to the beach and released.

Another major project in India involved in preserving the olive ridley sea turtle population was carried out in Chennai, where the Chennai wildlife team collected close to 10,000 eggs along the Marina coast, of which 8,834 hatchlings were successfully released into the sea in a phased manner.[25]

References

  1. ^ a b c d e f Abreu-Grobois, A.; Plotkin, P.; et al. (IUCN SSC Marine Turtle Specialist Group) (2008). "Lepidochelys olivacea". IUCN Red List of Threatened Species. 2008: e.T11534A3292503. doi:10.2305/IUCN.UK.2008.RLTS.T11534A3292503.en. Retrieved 12 November 2021.
  2. ^ "Appendices | CITES". cites.org. Retrieved 14 January 2022.
  3. ^ Fritz, Uwe; Havaš, Peter (2007). "Checklist of Chelonians of the World" (PDF). Vertebrate Zoology. 57 (2): 169–170. ISSN 1864-5755. Archived from the original (PDF) on 1 May 2011. Retrieved 29 May 2012. Alt URL
  4. ^ a b "Olive ridley Turtle". Retrieved 24 February 2018.
  5. ^ a b Biology and conservation of ridley sea turtles. Pamela T. Plotkin. Baltimore: Johns Hopkins University Press. 2007. ISBN 978-0-8018-8611-9. OCLC 71006746.{{cite book}}: CS1 maint: others (link)
  6. ^ a b c d "Olive ridley Turtle". wwfindia.org.
  7. ^ a b c "Lepidochelys olivacea" at the Encyclopedia of Life. Retrieved 16 April 2013.
  8. ^ a b c d e f g h i j k l m n o p q r s t u v "Recovery Plan for U.S. Pacific Populations of the Olive Ridley Turtle (Lepidochelys olivacea)". Silver Spring, MD: National Marine Fisheries Service. 1998. Retrieved 16 April 2013.
  9. ^ Ellis, Richard (2003). The Empty Ocean: Plundering the World's Marine Life. Washington: Island Press. ISBN 1597265993.
  10. ^ Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Lepidochelys olivacea, p. 221).
  11. ^ "Marine Turtle Newsletter" – Harold A. Dundee
  12. ^ a b c d e f g h i j k Ernst, Carl H.; Barbour, Roger W.; Lovich, Jeffrey E. (1994). Turtles of the United States and Canada. Washington [u.a.]: Smithsonian Inst. Press. ISBN 1560983469.
  13. ^ "Scan results 'good news' for health of stranded sea turtle", Retrieved on 26 January 2017.
  14. ^ "Olive ridley turtle found injured off Seaford beach". BBC News. 19 January 2020. Retrieved 19 January 2020.
  15. ^ a b "Lepidochelys olivacea – Olive Ridley Turtle, Pacific Ridley Turtle". Species Profile and Threats Database. Department of Sustainability, Environment, Water, Population and Communities. Retrieved 16 April 2013.
  16. ^ Carr, A. (March 1972). "Great Reptiles, Great Enigmas". Audubon. 74 (2): 24–35.
  17. ^ Spotila, James R. (2004). Sea Turtles: a Complete Guide to their Biology, Behavior, and Conservation. Baltimore: Johns Hopkins University Press. p. 132. ISBN 0801880076.
  18. ^ a b c d e f g Pamela T. Plotkin, ed. (2007). Biology and Conservation of Ridley Sea Turtles. Baltimore: Johns Hopkins University Press. ISBN 978-0801886119.
  19. ^ "Forging a Future for Pacific Sea Turtles" (PDF). Oceana. 2007. p. 6. Retrieved 16 April 2013.
  20. ^ "Rare turtles rescued in Ka'u". 9 February 2021.
  21. ^ Figgener, Christine; Bernardo, Joseph; Plotkin, Pamela T. (24 July 2019). "Beyond trophic morphology: stable isotopes reveal ubiquitous versatility in marine turtle trophic ecology". Biological Reviews. 94 (6): 1947–1973. doi:10.1111/brv.12543. ISSN 1464-7931. PMC 6899600. PMID 31338959.
  22. ^ "Jaguar v. sea turtle: when land and marine conservation icons collide". news.mongabay.com.
  23. ^ Shanker, K.; Ramadevi, J.; Choudhury, B. C.; Singh, L.; Aggarwal, R. K. (16 April 2004). "Phylogeography of olive ridley turtles (Lepidochelys olivacea) on the east coast of India: implications for conservation theory". Molecular Ecology. 13 (7): 1899–1909. doi:10.1111/j.1365-294X.2004.02195.x. PMID 15189212. S2CID 17524432.
  24. ^ Karnad, Divya; Isvaran, Kavita; Kar, Chandrasekhar S.; Shanker, Kartik (1 October 2009). "Lighting the way: Towards reducing misorientation of olive ridley hatchlings due to artificial lighting at Rushikulya, India". Biological Conservation. 142 (10): 2083–2088. doi:10.1016/j.biocon.2009.04.004.
  25. ^ "Over 8000 turtle hatchlings released", Deccan Chronicle, Chennai, 23 May 2014. Retrieved on 23 May 2014.
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Olive ridley sea turtle: Brief Summary

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The olive ridley sea turtle (Lepidochelys olivacea), also known commonly as the Pacific ridley sea turtle, is a species of turtle in the family Cheloniidae. The species is the second-smallest and most abundant of all sea turtles found in the world. L. olivacea is found in warm and tropical waters, primarily in the Pacific and Indian Oceans, but also in the warm waters of the Atlantic Ocean.

This turtle and the related Kemp's ridley turtle are best known for their unique synchronised mass nestings called arribadas, where thousands of females come together on the same beach to lay eggs.

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Tortue olivâtre

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Lepidochelys olivacea

Lepidochelys olivacea, la tortue olivâtre est une espèce de tortues de la famille des Cheloniidae[1].

Elle doit son nom à la couleur olive de sa carapace. Cette espèce est en voie de régression et fait l'objet localement d'un plan de restauration.

Distribution et lieux de ponte

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Distribution et lieux de pontes de la tortue olivâtre
Point rouge=lieux de pontes principaux
Point jaune=lieux de pontes secondaires

Cette espèce se rencontre dans les eaux inter-tropicales. Cependant, elles ne disposent pas de beaucoup de lieux de ponte sûrs. Un des plus importants, en Inde, est menacé par l'industrialisation. Bien que les États-Unis aient déclaré l’espèce comme étant en danger, sa population diminue en Atlantique Nord. Les populations stagnent ou sont en légère augmentation dans l'océan Pacifique. Les plus importants sites d'Inde, dans l’État d'Orissa, sont les plages de Devi, Rushikulya et Gahirmatha. Ce dernier site est gravement menacé par l'industrialisation[2].

Alors qu'on pensait qu'elles ne se reproduisaient pas en mer Rouge, on a découvert plusieurs sites de nidification dans la région de l'Érythrée[3],[4].

Description

La tortue olivâtre mesure entre 50 et 75 cm de long et a une masse d'environ 45 kg[5].

Sa dossière est plutôt plus bombée (la région nuchale surélevée) que celle de la tortue de Kemp. La dossière est verdâtre à ocre brun. Les bords sont légèrement retournés.

Alimentation

Cette tortue marine est une omnivore opportuniste : elle broute des algues[6] et mange des crustacés, des échinodermes, des méduses, des mollusques et des poissons[7].

Reproduction

La maturité sexuelle est atteinte entre 7 et 9 ans. Les pontes durent de 20 à 40 minutes. Cette espèce pond quelques fois seule. Le nid est creusé sur 50 à 60 cm de profondeur. Chaque ponte produit entre 30 et 170 œufs. La femelle pond de 1 à 3 fois par intervalles de 17 à 29 jours au cours d’une saison. L’incubation dure entre 46 et 62 jours selon la température du sol[8].

Systématique

Les principaux groupes évolutifs relatifs sont décrites ci-dessous par phylogénie[9] selon Hirayama, 1997, 1998, Lapparent de Broin, 2000, and Parham, 2005 :

--o Chelonioidea Bauer, 1893 |--o | |--o †Toxochelyidae | `--o Cheloniidae | |--o Carettini | | `-- Caretta Rafinesque, 1814 | |--o Natator McCulloch, 1908 | `--o Chelonini | |--o Eretmochelys Fitzinger, 1843 | `--o | |--o Lepidochelys Fitzinger, 1843 | | |--o Lepidochelys kempii (Garman, 1880) | | `--o Lepidochelys olivacea (Eschscholtz, 1829) | `--o Chelonia Brongniart, 1800 `--o Dermochelyidae 

Les deux espèces de Lepidochelys partagent le nom vernaculaire de « tortue bâtarde ».

Tortue olivâtre et l'Homme

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Une tortue olivâtre prise dans un filet abandonné aux Maldives.

Comme toutes les tortues marines, elle est principalement menacée par la disparition des plages due à l'industrialisation et à l'urbanisation ; mais aussi, dans une moindre mesure, par d'autres activités humaines : surpêche, filets abandonnés, déchets en mer et braconnage ainsi que des « prises involontaires » qu'elle subit. La pêche au chalut est particulièrement mortelle pour les tortues marines, mais ces prises involontaires peuvent être fortement réduites : par exemple, sur les côtes américaines, le dispositif d’exclusion des tortues limite les prises accidentelles par les chalutiers ; en ce qui concerne le braconnage, le ramassage des œufs, notamment en Amérique centrale, est encore très important.

En France, elle est concernée par un plan de restauration des tortues marines des Antilles françaises (plan local et régional qui concerne aussi d'autres tortues Marines des Antilles Françaises (tortue imbriquée, tortue verte, tortue luth, tortue olivâtre). Ce plan est subdivisé en :

  • - un Plan de Restauration des Tortues Marines de Guadeloupe,
  • - un Plan de Restauration des Tortues Marines de Martinique,
  • - un projet de programme de coopération internationale à développer à échelle géographique plus large, voire planétaire afin de mieux prendre en compte les métapopulations et la diversité génétique des espèces.

Une campagne de protection internationale a été lancée par June Haimoff pour la protection des tortues. Plusieurs projets sont menés par le WWF en Inde et Amérique du Sud pour limiter les prises accidentelles et protéger les sites de nidification[10] aussi bien en Inde qu'en Amérique du Sud.

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Un spécimen atteint d'albinisme ou de leucistisme à Kélonia, sur l'île de La Réunion

Publication originale

  • Eschscholtz, 1829 : Zoologischer Atlas, enthaltend Abbildungen und Beschreibungen neuer Thierarten, wehrend des Flottcapitains von Kotzebue zweiter Reise um die Welt, auf der Russisch-Kaiserlichen Kriegsschlupp Predpriaetiâ in den Jahren 1823-1826. (texte intégral)

Notes et références

  1. TFTSG, consulté lors d'une mise à jour du lien externe
  2. (en) « Turning Turtle », Greenpeace (consulté le 29 mai 2007)
  3. (en) Nicolas Pilcher; Sammy Mahmud; Steffan Howe; Yohannes Teclemariam; Simon Weldeyohannes, « An Update on Eritrea’s Marine Turtle Programme and First Record of Olive Ridley Turtle Nesting in the Red Sea », Marine Turtle Newsletter, vol. 111, no 16,‎ 2006 (résumé)
  4. « The Eritrean Turtle Team Finds Hatched ‘Oliver idly’ in Rastarma » (consulté le 6 mars 2006)
  5. Marie-Paul Zierski et Philipp Röhlich, La grande encyclopédie des animaux, Terres éditions, juillet 2019, 320 p. (ISBN 978-2-35530-295-4), Tortue bâtarde page 133
  6. Collectif (trad. Michel Beauvais, Marcel Guedj, Salem Issad), Histoire naturelle [« The Natural History Book »], Flammarion, mars 2016, 650 p. (ISBN 978-2-0813-7859-9), Tortue olivâtre page 374
  7. Alain Diringer (préf. Marc Taquet), Mammifères marins et reptiles marins de l'océan Indien et du Pacifique, Éditions Orphie, 2020, 272 p. (ISBN 979-10-298-0254-6), Tortue olivâtre pages 66-67
  8. « Tortue olivâtre », Réseau d'information sur les tortue d'Outre-mer
  9. (en) « Dermochelyoidea - leatherback turtles and relatives », Mikko's Phylogeny Archive (consulté le 17 mai 2007)
  10. « Olive ridley turtle », WWF (consulté le 29 mai 2007)
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Tortue olivâtre: Brief Summary

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Lepidochelys olivacea

Lepidochelys olivacea, la tortue olivâtre est une espèce de tortues de la famille des Cheloniidae.

Elle doit son nom à la couleur olive de sa carapace. Cette espèce est en voie de régression et fait l'objet localement d'un plan de restauration.

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Distribution

provided by World Register of Marine Species
cosmopolitan in warm water (not N Atlantic)
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bibliographic citation
van der Land, J. (ed). (2008). UNESCO-IOC Register of Marine Organisms (URMO). Xiong, W.; Shen, C.; Wu, Z.; Lu, H.; Yan, Y. (2017). A brief overview of known introductions of non-native marine and coastal species into China. <em>Aquatic Invasions.</em> 12(1): 109-115.
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