Reef Report for Tuesday, January 16, 2007
Sea Turtle Hatching Season Begins along the Great Barrier Reef
Residents and visitors urged to help protect hatchlings.
The Great Barrier Marine Park Authority announced the start of the Sea Turtle hatching season this past week, which locals know means that it’s time to help protect these small hatchlings.
The Great Barrier Reef is unique in that 6 of the seven species of the world’s sea turtles both live in the water and nest on mainland and island beaches adjacent to the reef.
We commonly see them just offshore from our home in Trinity Beach, where they graze on the algae covered rocks and sea grass beds. It’s a part of a very unique life cycle, which culminates in the nighttime hatching of sea turtles from January through April.
Adult females spend their time feeding throughout the year on their feeding grounds, which for some species may be hundreds, even thousands of miles from their nesting areas. Weight gain and environmental cues trigger the nesting response, whose first step is migration back to their nesting grounds. About a month before the laying eggs the adult females will mate with one or more of the males that they encounter. Sea Turtles are extremely faithful to their nesting sites, returning to the place they hatched years ago, to crawl onto the beach, dig a shallow pit, and lay their eggs in the pit. They then cover the pit, and crawl back into the ocean, leaving the sun to incubate the eggs.
Temperature of the eggs must be in a specific range for them to hatch. The temperature of eggs in the nest must be between 23 ° and 33 °C, temperatures outside this range will cause the eggs to die. Within the 23 ° and 33 °C range eggs that incubate in the lower parts of this range become males, eggs incubating in the upper range become females. Seven to ten weeks later the turtles hatch from their eggs by tearing through the egg’s leathery shell, and then claw up through the sand to the surface. By instinct they move towards the brightest horizon, which is usually the ocean, where they are on their own.
Less than one in a thousand eggs ever hatches and grows into an adult, which is why any unnecessary additional death of a hatchling can have an impact on their populations which can grow only very slowly.
So the locals know how to protect hatchlings, we hope you follow these guidelines as well, and are lucky enough to someday see sea turtles along the reef.
-Don’t disturb nests or hatchlings
-No lights or flashlights on hatchlings (this disorients them and can cause them to move away, rather than towards the ocean.
-Reduce outdoor lighting during laying and hatching seasons.
-Follow directions given on signage posted on nesting beaches.
-Refuse to buy sea turtle products (tortoiseshell jeweler, souvenirs, meat and eggs).
-Turn off street lights and screen house lights adjacent to sea turtle rookeries.
-Keep dogs from nesting beaches.
-Do not throw plastic bags, fishing line and other rubbish into the sea or onto the beach.
-Follow the turtle watching guidelines whenever you encounter a nesting sea turtle or hatchlings.
-Support international conservation agencies that are trying to reduce turtle harvests to ecologically sustainable levels.
-Assist turtle research and conservation by reporting dead or injured turtles to the turtle hotline (in Australia phone: 008 801 500).
-Volunteer on sea turtle conservation projects.
While sea turtle populations in Australia are relatively stable, all six species are considered sensitive here, and are threatened or endangered elsewhere in the world. Many things contribute to their precarious status, including destruction and alteration of nesting and foraging habitats; incidental capture in commercial and recreational fisheries; entanglement in marine debris; pollution, and vessel strikes. Global warming may also start to impact sea turtles, especially the temperatures of their nesting beaches. In increase of just a few degrees can both upset the gender balance of the hatchlings or kill the eggs.
Turtle Hatching Season begins at Mon Repo beach.
Turtle Hatching Season begins in Cape York.
Cape York Turtle Rescue, the organization that operates the Mapoon project, and their opportunities for you to participate.
More information about sea turtles in Australia.
The weekly reef report is written by Joel Groberg of DiveTheReef.com,
who compiles them from the many conversations he has with dive staff in the area, as well as many other local sources in the dive
Index of all reef reports.