Movements of leatherback turtles in the Pacific Ocean from nesting to feeding areas
NOAA scientists found that most adult leatherback sea turtles in the Pacific Ocean return to the same feeding areas between nesting seasons--something that was unknown prior to this study.
The research team found that turtles moving into the South China Sea and to the North Pacific Transition Zone nearly all had low stable nitrogen (d15N) signatures, while those crossing to the eastern Pacific had high stable nitrogen (d15N) signatures. Turtles integrate specific isotopic signatures from the areas they eat, and the signatures are retained in their body tissues for several months.
Initially, researchers conducted isotope analyses on non-satellite tracked nesting turtles in the western Pacific. They found a bimodal stable nitrogen (d15N) distribution (yellow bars in graph). Remotely-sensed ocean color data showed high levels of nitrogen fixation in the western Pacific (believed to decrease d15N signals) and high levels of denitrification in the eastern Pacific (believed to increase d15N signals). By integrating stable isotope analysis with satellite tracking, scientists revealed the movements of leatherback turtles feeding in the Pacific Ocean.
By examining isotopes to determine feeding area before nesting and using satellite tracking after nesting, the research team's results indicate that most adults return to the same feeding areas between nesting seasons.
These results provide the first-ever evidence of fidelity to specific feeding areas by leatherback turtles and underscores the relative importance of different Pacific regions for leatherbacks nesting in Indonesia.
When linked with information on fisheries effort, data from this study can also reveal the ocean regions in which leatherbacks are most susceptible to fisheries interactions.
Jeffrey Seminoff and Scott Benson from NOAA Fisheries' Marine Turtle Ecology & Assessment Program in the Southwest Fisheries Science Center in La Jolla, CA, led this research. Results of the study were published in the journal PLoS ONE:
An oceanic whitetip shark swims near the surface of the water. Photo courtesy of John Carlson.
Veteran intern Antonio Jones at an oyster farm in Drayton Harbor, Washington, checking traps for European Invasive Green Crab. Credit: Northwest Straits Commission
A bidder checks the quality of tuna at the Honolulu Fish Auction. Credit: NOAA Fisheries
