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Inter-nesting Patterns and Migration Pathways of Green Turtles at Raine Island

 

Raine Island in far north Queensland, Australia, is the world’s largest green turtle nesting rookery. Turtle biologists are alarmed about three signs that show the nesting turtle population is stressed:

  •  the size of nesting turtles on the island has decreased in the last 10 years, suggesting younger and less fit females are having to make the breeding migration as larger females are lost from the population due to threats such as hunting;
  • >20% of the turtles arriving each year are breeding for the first time, which also suggests that larger, experienced female turtles have been lost;
  • there has been an increase in the number of years between nesting events as turtles are not fit enough to breed as often due to lack of food and stress at their feeding grounds.

These signs give us clear warning of a significant problem for green turtles in the western Pacific. To understand the problem, we need to know more about the nesting turtles at Raine Island.

These turtles may also use other islands in the area. However, we don’t know very much about the movements of turtles between nesting at Raine Island and surrounding coral cays. Sea Turtle Foundation used satellite transmitters to collect data on turtle movements between Raine Island and other islands and the habitat they used whilst in the area. This will let us understand the threats to turtles while they are breeding and the type of habitat they prefer to use in between nesting events.

Green turtles do not live where they nest. This study also let us follow the migration paths of females from Raine Island back to their home or feeding ground. This information will help improve regional and international conservation management strategies.

This project was sponsored by Australian Geographic, who kindly raised money to allow Sea Turtle Foundation to buy satellite transmitters to attach to four green turtles at Raine Island.

Four Townsville schools named the turtles that were tracked:

  •  Belgian Gardens State School’s turtle was called ‘BG Ranger
  •  Currajong State School’s turtle was called ‘Jong Jong
  •  Kelso State School’s turtle was called ‘Kelso
  •  The Willows State School’s turtle was called ‘Squirtle