To successfully recover populations, the complex life histories of
long-lived marine turtles must be understood.
This complex life history begins as
hatchling sea turtles leave their natal beach. There they traverse
the beach, enter the sea, and migrate into the open where they will
spend several years feeding at the surface and being transported by
currents.
After this pelagic phase, immature sea turtles of most species
occupy what are termed developmental habitats. This may be one or a
series of habitats, usually in coastal waters, where adult turtles
may or may not be present. Adults occupy one or more feeding
grounds which may be distinct from areas inhabited by immature
turtles. From these foraging grounds, adults undertake periodic
breeding migrations to nesting beaches that may be hundreds of
miles away. Taken together, the various life history stages of
turtles from a single population take place over vast expanses of
ocean, in some cases entire ocean basins.
Studies underway at five locations in
Florida and adjacent waters are attempting to identify and
characterize distinct life history stages for four species of
marine turtles: green turtles, loggerheads, Kemp's ridleys, and
hawksbills.
Turtles are captured at sea by various methods, measured, tagged
(if possible), and released. Blood samples are collected for DNA
sequencing, to determine genetic identity (nesting beach origin),
and to allow sex determination of immature animals.
Identification of life
history stages is assisted by laparoscopic and histological
studies. Other data gathered allow determination of diet, habitat
preferences, extent of residency within an area, behavioral
strategies, and seasonality. All of these data are used for stock
identification, population modeling, management decisions with
bearing on sex ratios (hatcheries and nest relocation) and for
development of field techniques for sexing sea turtles to be used
by other investigators.
Objectives
The objectives of these studies are to identify and characterize
life history stages of marine turtle species that occur in Florida
waters, to identify habitats specific to life history stages, and
to identify threats to specific life history stages. Population
biology data (i.e., population structure and dynamics, sex ratio,
genetic identity, size at maturity, and so on), and ecology and
behavior data (i.e., dietary preferences, habitat requirements,
"home ranges," seasonality, and behavioral strategies) are
necessary for understanding the numerous complexities of these life
history stages.
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