Description and Status

Scientific Name: Chelonia Mydas
Common Name: green sea turtle
Chamorro Name: Haggan or Haggan Bedi

Green sea turtles were once a common species of sea turtles found in Guam’s waters. They can still occasionally be seen around the island where rich sea grass beds are found, including channel areas, harbors, lagoons and also in shallow reef areas while the turtles are foraging for sea grass and marine algae.

An endangered and threatened species

Prior to the 1978 Endangered Species Act listing of green sea turtles, there were no regulations controlling the taking of the turtles on Guam, although regulatory measures had been under discussion by the local government since at least 1973. When the Endangered Species Act of Guam was passed in 1979, green sea turtles were given full legal protection at the local government level consistent with Federal regulations.

World wide concern for over harvesting of these turtles also resulted in the green sea turtle being listed on the Federal Threatened Species List and the Guam Endangered Species List. The Federal and Guam Endangered Species acts state that it is illegal to capture, harass, possess, buy, sell, or transport the sea turtles or any part of the turtles including the eggs, shells, shell jewelry and meat.

Description

Green sea turtles can grow to approximately 1.2 meters (four feet) in shell length and can weigh up to approximately 136 kilograms (300 pounds). Being marine reptiles, the green sea turtles have slow growth rates. In the wild, the green sea turtles grow approximately 0.4 inches (1 centimeter) per year until maturity, then 0.2 inches (0.5 centimeters) after.

These turtles can live to be about eighty years old.

Characteristics of the green sea turtle include a set of prefrontal scales between the eyes, a single claw on each front flipper, fused shell plates on the carapace, and rounded edges on the carapace. The male sea turtle has a longer, thicker tail than the female.

The start of sexual maturity is believed to be twenty-three years of age at thirty-two inches in length of carapace (back shell). This sea turtle can deposit forty to 140 eggs in a single clutch (nest) depending on the size of the female and the amount of eggs she can contain. The female can lay as many as six clutches in a season, however, only returning every three to five years later to again nest in the sand and sandy vegetation.

The incubation of the eggs range from fifty to ninety days and is dependant on weather conditions. The hatchlings, usually two inches in length, crawl up from the inside of the sandy mound towards the top of the nest and generally emerge before sunrise. It may take as long as two days to complete the process of hatching. Once hatched, the hatchlings head towards the ocean and feed on marine vegetations such as saragassum (seaweed) and other algae while adrift.

Species management

Biologists at the Division of Aquatic and Wildlife Services at the Department of Agriculture on Guam track green sea turtles by tagging them with electronic devices paid for by the U.S. Navy through a grant to the National Oceanic and Atmospheric Administration (NOAA). This program, started in 2000, is called the Guam Sea Turtle Recovery Program. The satellite time to track the tagged turtles is estimated at $15,000 per year, and each tag cost $3,000.

The Government of Guam Department of Agriculture, Dvision of Aquatic & Wildlife Resources (DAWR) is responsible for performing baseline population studies on the sea turtles. Additionally, a Haggan Watch volunteer project was created in 2005 to minimize the threats to sea turtles and enhance successful nesting events by having volunteers sit on the beach and keep a protective eye on the turtles as they nest.

Only three adult female green sea turtle nesters have been captured, tagged and released since the program began in 2000. The first turtle to be tagged in this program was an adult female green sea turtle spotted crawling on the beach on Andersen Air Force Base in June 2000. A team of military and local biologists named the turtle Pati, measured it, tagged it and then let it go. Pati’s shell measured 110 centimeters in length. She was tracked swimming to the Sulu Archipelago, Philippines. Pati was last heard from in Kulisi-An, Pangutaran, Province of Tawi-Tawi, south, within the Sulu Sea, in an area called the Turtle Islands. These islands are important feeding areas for green sea turtles.

Two other nesting female turtles were captured and tagged in April 2007 by Government of Guam’s Department of Agriculture Division of Aquatic and Wildlife Resources Sea Turtle Recovery team along with Haggan Watch volunteers. One of the turtles, referred to as Sea Turtle 66746, rendered it’s last transmission off the shores of Mindanao in the Philippines on July 11, 2007. The last transmission of the other turtle, known as Sea Turtle 66748, was off the shores of Kume Shima Island near Japan on September 9, 2007.

Whether the tagged turtles will return to nest on Guam again is only guesswork at this time. They face many hurdles such as drift and other fishing nets deep at sea, plastic debris, sharks and hunters in places where catching turtles is not prohibited.

Historical significance

Green sea turtles have had an intricate historic role in Chamorro culture and diet. Turtle was traditionally eaten at feasts in the past, including weddings, funerals and other ceremonial events. Both the meat and eggs were served as delicacies.

Chamorros used turtle shells to craft jewelry including bracelets, necklaces, and pendants. Turtle shells were also used to make children’s wealth called guinahan fama’guon which was worn as a necklace.

Turtle bones were traditionally used to make tools as well.

Current threats

Predators for turtle eggs and hatchlings on the shore are rodents, monitor lizards, birds, wild pigs, deer, stray cats, and dogs. Use of vehicles on the seashore creates an additional threat to eggs and hatchlings. Driving on the beach can compress the mound or nest which can trap hatchlings, creating a barrier between the nest and the ocean. Litter on the shore can also be a threat as it gets worked into the nest by the female as she covers the clutch (nest).

Another threat to green sea turtles is habitat loss as the island becomes more populated.

Once in the ocean, hatchlings may succumb to predators such as fish, octopus, sharks, birds, and crabs. Additional threats include debris such as balloons, plastic bags, and other non biodegradable items that can be ingested by the sea turtle causing respiratory complications. Drifting ropes and nets can entangle a sea turtle causing it to drown and die.

The migration route of green sea turtles also causes concern among scientists as the sea turtle migrates into an area where the harvest of the species is legal and or acceptable. This harvesting is expected to contribute to the decline of the sea turtles on Guam and the region.

By Shawn Wusstig
Haggan Watch Volunteer Project Supervisor
Guam Sea Turtle Recovery Program, Division of Aquatic and Wildlife Resources
Department of Agriculture, Government of Guam

For further reading

“Green sea turtle migrates over 2,000 km from Guam to Okinawa.” Japan Today, May 8, 2008.

Guam Department of Agriculture. Annual Report 2002 Government of Guam Department of Agriculture. Mangilao, Gu:Guam Division of Aquatic & Wildlife Resources, 2002.

Guam Department of Agriculture. Annual Report 2007 Government of Guam Department of Agriculture. Mangilao, Gu:Guam Division of Aquatic & Wildlife Resources, 2007.

National Marine Fisheries Service. Subsistence Use of Sea Turtles at Pacific Islands Under the Jurisdiction of the United States. Southwest Fisheries Center Administrative Report H-83-17, Honolulu: U.S. Department of Commerce National Oceanic and Atmospheric Administration, September 1983. Also available online at Pacific Islands Fisheries Science Center (accessed 1 September 2017)

Weekly Japan Update. “Pacific Traveling Sea Turtle Tracked to Kume Island.” May 16, 2008. Available online at Weekly Japan Update (accessed 1 September 2017)

“My Haggan Dream.” Vimeo, 2016. Featuring Kaya Rain S. Rasa. Produced by Sisbro Studios and Open Boat Films. Funded by NOAA. https://vimeo.com/180350366.

Resources for teachers

Below are some websites featuring educators’ guides that teachers can use in classrooms for lessons on turtle conservation:

Other resources can be found by visiting the following organizations’ websites: