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In-Water Research Studies

To successfully recover populations, the complex life histories of long-lived marine turtles must be understood.

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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.