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Family : DERMOCHELYIDAE
Species : Dermochelys coriacea
Maximum carapace length : 2.5 metres
The unique Leatherback Turtle (or
'Leathery Turtle') is a widespread, but threatened, species listed
as 'Vulnerable' by
IUCN in 2013. Southeast Asia populations are
considered to be of two distinct subgroups comprising the Northeast Indian
Ocean group, and the West Pacific Ocean group. The latter are categorised as 'Critically Endangered'.
In Southeast Asia, the Leatherback Turtle occurs in parts of
Myanmar, Thailand, Cambodia, Malaysia, Indonesia, Brunei and the
Philippines.
These are oceanic turtles which migrate great distances from their nesting sites to
their feeding areas. They have been recorded diving to depths of greater
than 1200 metres. They mainly prey on soft-bodied animals such as jellyfishes, salps (a jellyfish-like
chordate) and siphonophores (which are floating, colonial hydrozoans).
Adults lack scales (scutes), however their dark, white-spotted, leathery carapace is
strengthened by 7 longitudinal ridges (the carapace of hatchlings do bear
tiny scales). Their long forelimbs and short hindlimbs lack claws.
Maturity and longevity estimates vary widely, but it seems
likely that they mature at around 20 years old, and live to around 30 or so.
Females return to nesting beaches every few years to deposit up to 10
clutches of eggs, with up to 90 eggs in a clutch.
Threats to this ancient turtle, whose early ancestors evolved over 100
million years ago, are numerous and include over-harvesting of eggs,
low hatching success, egg predation by feral dogs, exploitation of nesting females
for consumption and commercial
products, death due to fisheries bycatch,
marine pollution, climate change affecting sand temperatures, and loss
of nesting sites due to coastal development.
Despite decades of conservation efforts, the famed nesting beaches at Terennganu on the east coast of Peninsular Malaysia,
where there were around 5000 nestings in the 1960's, were rarely visited by
the 1990's (Chan & Liew, 1996): populations here are now considered to be 'functionally extinct'.
Hamann et al (2006) concluded that "... they did not protect soon enough
for the population (in Terennganu) to be able to cope with fisheries and other pressures in
the 1970s and 1980s". The establishment of the Rantau Abang Turtle Sanctuary
in 1988 was well meant, but clearly too late to help this species.
There is still some hope, however: in 2017 a Leatherback Turtle landed at Rantau
Abang after a 7-year absence (Straits Times, 11 Sep 2017), and in 2019
proposals were floated to attempt reintroduction by the purchase of eggs
from Papua New Guinea and Indonesia (The Star, 15 Jul 2019).
Figs 1 and 2 : Front and side view of adult, female Leatherback Turtle
(locations undisclosed).
Fig 3 : Typical turtle nesting beach on the east coast of Peninsular
Malaysia, in the state of Terennganu. Such beaches are typically long and steeply sloping, with coarse sand.
Fig 4 : Hatchlings making their first foray into the ocean.
References :
Chan, E.H. & Liew, H.C. (1996). Decline of the leatherback population in
Terengganu, Malaysia, 1956- 1995. Chelonian Conservation and Biology 2:
196-203.
Hamann, M., Ibrahim, K. & Limpus, C. (2006). Status of leatherback
turtles in Malaysia. M. Hamann, C. Limpus, G. Hughes, J. Mortimer, and
N. Pilcher (Comp.), Assessment of the Conservation Status of the
Leatherback Turtle in the Indian Ocean and South East Asia, IOSEA
Species Assessment, 1, 78-82.
Wallace, B.P., Tiwari, M. & Girondot, M. 2013. Dermochelys coriacea.
The IUCN Red List of Threatened Species 2013.
Links :
Endangered leatherback turtle returns to Rantau Abang in Terengganu
after seven-year absence
(Straits Times, 11 Sep 2017)
Terengganu plans to buy turtle eggs to boost population (The Star,
15 Jul 2019)
Thanks to Rushan Bin Abdul Rahman for assistance.
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