Threatenend Species of the NT - Olive Ridley turtle.... by Parks and Wildlife Commission Northern...
2
THREATENED SPECIES OF THE NORTHERN TERRITORY OLIVE RIDLEY PACIFIC RIDLEY Lepidochelys olivacea Conservation status Australia: Endangered. Northern Territory: Data Deficient. Description The olive ridley is the smallest Australian sea turtle, with a mean curved carapace length of 70 cm. Carapace colour is oliv e-grey. The carapace has a diagnostic six pairs of costal scales. Eggs are small in size (mean diameter = 3.6 cm) compared with all other marine turtles that breed in the NT. Olive ridley turtle. (Copyright: State of Queensland, reproduced with permission of the Environmental Protection Agency) Distribution Olive ridley turtles occur in tropical and subtropical waters throughout the world. The vast majority of the nesting population in Australian waters occurs in the Northern Territory. Nesting has been recorded from Melville Island to Groote Eylandt with the highest nesting occurring on Melville Island, islands to the east of Croker Island and some islands off northeast Arnhem Land (Chatto 1998). Conservation reserves where reported : Casuarina Coastal Reserve, Garig Gunak Barlu National Park, Kakadu National Park, Nanydjaka Indigenous Protected Area. Known locations of olive ridley ο = pre 1970 • = post 1970 Ecology Olive ridleys live in shallow protected waters and feed on benthic molluscs, crabs, echinoderms and gastropods. Studies elsewhere indicate some long- distance dispersal between feeding and breeding grounds. In the NT, olive ridleys breed at a wide range of sites on islands and, less commonly, mainland beaches. Olive ridleys often nest just above the high tide mark and may suffer more breeding losses through tidal inundation than do other species of marine turtle (Chatto 1998).
Transcript of Threatenend Species of the NT - Olive Ridley turtle.... by Parks and Wildlife Commission Northern...
8/8/2019 Threatenend Species of the NT - Olive Ridley turtle.... by Parks and Wildlife Commission Northern Territory
http://slidepdf.com/reader/full/threatenend-species-of-the-nt-olive-ridley-turtle-by-parks-and-wildlife 1/2
8/8/2019 Threatenend Species of the NT - Olive Ridley turtle.... by Parks and Wildlife Commission Northern Territory
http://slidepdf.com/reader/full/threatenend-species-of-the-nt-olive-ridley-turtle-by-parks-and-wildlife 2/2
Conservation assessmentIn recognition of world-wide trends,and a substantial array of threateningfactors, the olive ridley turtle isregarded as Vulnerable nationally
(Environment Australia 2003).
In the NT, there are no accuratepopulation estimates. The femalebreeding population in the NorthernTerritory is very roughly estimated tobe between 1,000 to 5,000. There areno substantial data on trends inpopulation; and the species remainscommon and widespread. There issome anecdotal evidence of at leastlocalised decline of marine turtles in
general (Kennett et al . 2004).
Given the presence of some threatsthat cannot be quantified and the lackof trend data the species is bestconsidered as Data Deficient.
Threatening processesAs with other marine turtles, manyfactors may that threaten this species.These include by-catch in commercialfisheries (Poiner and Harris 1996);
Indigenous harvest; predation of eggsand young by dogs, pigs and goannas;marine pollution, includingentanglement in ghost nets; anddisturbance at main breeding sites.
Mortality of animals does occur due tocapture in fishing nets. The worstrecorded occurrence was in Fog Bayin 1991 when an estimated 300 turtleswere killed in one incident. Of 100turtles examined from this kill, 85%were olive ridleys. However, this levelof mortality is exceptional and annualbycatch is likely to be normally muchlower.
Conservation objectives andmanagementA national recovery plan for thisspecies, and other marine turtles, wasimplemented in 2003 (EnvironmentAustralia 2003).
This plan includes actions that: (i) aimto reduce mortality of turtles(principally through ameliorativeactions within commercial fisheries,and maintenance of sustainableharvest by Indigenous communities),(ii) develop and integrate monitoringprograms; (iii) manage factors thataffect reproductive success (in thiscase, outside NT); (iv) identify andprotect critical habitat (including seagrass beds); (v) enhancecommunication of information; and (vi)enhance international actions andcooperation.
Increasing numbers of wild dogs on
Melville Island were thought to becausing unusually high levels of nestpredation. Since 2005, dog numberson this island have been controlledthrough joint actions of Tiwi and Parks& Wildlife rangers.
Compiled byRobert TaylorRay ChattoJohn Woinarski[May 2006]
ReferencesChatto, R. (1998). A preliminary overview
of the locations of marine turtlenesting in the Northern Territory. InMarine turtle conservation and management in northern Australia .(eds R. Kennett, A. Webb, G. Duff, M.Guinea and G. Hill.) pp. 33-40.(Northern Territory University,Darwin.)
Environment Australia (2003) Recovery Plan for marine Turtles in Australia .(Environment Australia, Canberra.)
Kennett, R., Robinson, C.J., Kiessling, I.,Yunupingu, D., Munungurritj, N., andYunupingu, D. (2004). Indigenousinitiatives for co-management ofMiyapunu/sea turtle. Ecological Management & Restoration 5, 159-166.
Poiner, I.R., and Harris, A.N.M. (1996).Incidental capture, direct mortalityand delayed mortality of sea turtles inAustralia's Northern Prawn Fishery.Marine Biology 125, 813-825.
