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RESEARCH INTERESTS
Ecology and ethology of vertebrates
Ecology of marine turtles
Radiotelemetry of terrestrial reptiles
Role of ecotourism in conservation
PUBLICATIONS
Historically and economically speaking, marine turtles
are the world's most valuable reptiles. However, all
seven species are now endangered or threatened. For
these and other reasons there is a surge of scientific and
public interest in these animals. My research has taken
me to 18 countries where nesting or feeding
aggregations are found. Local and international students
are involved in the research working on small, specific
projects in the laboratory or on more general, global
projects.
My current research interests are in the ecology
and migration of the green turtle (Chelonia mydas).
These are large turtles well adapted to marine life.
They are circumglobal, commonly occurring in warm,
tropical seas. They occur in offshore waters or on the
nesting beaches of at least 139 countries and territories.
The green turtle is a morpho-species, made up of several
distinct populations and metapopulations. The total
range of a population encompassing the nesting beach,
epipelagic habitat, feeding ground and migrations can be
extensive. Hatchlings and small juveniles are chiefly
carnivorous while subadults and adults are mainly
herbivorous. Trophic level changes are associated with
ontogenetic habitat shifts.
Much more is known about the females than males
because the former are easily studied on the nesting
beaches. Females are characterized by slow growth,
delayed sexual maturity, high fecundity, iteroparity and a
relatively long reproductive life (under natural
conditions). My colleagues, students and I have reams of
data on several nesting populations in the Pacific and
Indian Ocean areas and these data are now being
analyzed. Long range demographic data on a couple of the
nesting beaches have disclosed significant annual
fluctuations in nesters. A green turtle survivorship
curve is roughly concave, under natural conditions.
Some major gaps (and potential research projects) in our
knowledge of green turtles are speciation rates, natural
sex ratios, ecologies of hatchlings and juveniles and
biology of males.
Because of many decades of overexploitation, most green
turtle populations are endangered or threatened today.
Conservation of any one population will almost certainly
involve regional cooperation (and herein lies potential
conservation type research projects).
My lab has all the necessary equipment to carry out
short and long range projects. Over the years,
international contacts have been established in areas
where sea turtles are still somewhat abundant. In these
areas, local and international students are engaged in
collaborative research.
Selected Publications
Balazs, G., H. Hirth, P. Kawamoto and E. Nitta. 1992.
Recovery plan Hawaiian sea turtles. NMFS/SWFC, 76 pp.
Hirth, H. and D. Rohovit. 1992. Marketing patterns of the
green and hawksbill turtles in Port Moresby, Papua New
Guinea. Oryx 26:39-42.
Hirth, H., M. Huber, T. Frohm and T. Mala. 1992. A natural
assemblage of immature green and hawksbill turtles on
reef of Wuvulo Is. Papua New Guinea. Micronesica
25: 145-153.
Hirth, H., J. Kasu and T. Mala. 1993. Observations on a
leatherback turtle nesting population near Pigua, Papua
New Guinea. Biological Conservation 65:77-
82.
Hirth, H. 1993. Marine turtles. In: Nearshore marine
resources of the South Pacific. (ed. A. Wright and L.
Hill) pp. 329-370. (International Center Ocean
Development, Canada)
Hirth, H. 1994. A leatherback sea turtle nesting
population in Papua New Guinea. Proceedings Second
World Congress of Herpetology 1:20, University of
Adelaide, Australia.
Hirth, H.F. 1997. Synopsis of biological data on the green
turtle. U.S. Dept. Interior. 120 pp., 17 tables, 15 figures.
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