……objective science for conservation…….

The Pacific WildLife Foundation is a non-profit coastal and marine research and education society  that inspires an appreciation for objective scientific research and conservation of the ocean. We conduct original research, develop novel education programs, and inspire an appreciation for conservation of the ocean. 

Hawksbill Sea Turtle Eretmochelys imbricata

By Jean Wai Jang

Hawksbills are considered to be the most tropical of all sea turtles. They prefer to feed in areas near coral reefs and rocky outcroppings in shallow coastal areas. The distribution of the Hawksbill turtle is circumtropical, occurring from 39^oEN to 30⁰ES latitude in the Atlantic, Pacific and Indian Oceans and the surrounding bodies of water. In the eastern Pacific Rim, 50 years ago, hawksbills found in near shore waters from Mexico to Ecuador were common to abundant. Today, hawksbills are rare in most areas and there are no known nesting beaches remaining on the Pacific coast of Mexico. In the Central Pacific nesting is widely distributed and scattered. Foraging areas have been reported in almost all the island groups of Oceania from the Galapagos Islands in the eastern Pacific to the Republic of Palau in the western Pacific. Hawksbills are also found to nest in the far western and southwestern Pacific islands and mainland of Southeast Asia, from China, Japan, Philippines, Malaysia, Indonesia, Papua New Guinea, the Solomon Islands and Australia.

Hawksbill Sea Turtle Identification

• two pairs prefrontal scales

• a beak-like mouth, hence the name and the lower jaw is V-shaped.

• Shell length: 30-35 inches (75-88cm)

• Hard carapace (shell) with large scutes (shell plates)

• 4 costal (lateral) scutes. First costal scute does not touch nuchal

• Shell is imbricated, overlapping scutes, serrated along the posterior edge

• Mass: 95-165 lbs (43-75 kg) record weight of one animal was 127 kg and was reported by Archie Carr in 1952.

• Color: carapace is dark amber with radiating streaks of brown or black and plastron is whitish-yellow.

• two claws on each flipper

• Hawksbill has an alternating gait, when they walk on land. 

• Sea turtle identification key can be found at: http://swr.nmfs.noaa.gov/pir/stid.htm

Helpful Links

• Identification Chart by Seaturtle.org http://www.seaturtle.org/documents/ID_sheet.pdf

• Recovery Plan for U.S. Pacific Populations of the U.S. Department of Commerce National Oceanic and Atmospheric Administration National Marine Fisheries Service U.S. Department of the Interior U.S. Fish and Wildlife Service Hawksbill Turtle (Eretmochelys imbricata), August 2007 http://www.nmfs.noaa.gov/pr/pdfs/recovery/turtle_hawksbill_pacific.pdf

• Animal Diversity Web: University of Michigan Museum of Zoology http://animaldiversity.ummz.umich.edu/site/accounts/information/Eretmochelys_imbricata.html

• Hawksbill Sea turtle: Pacific Whale Foundation, Maui Hawaii http://main.maui.net/~pacwhale/childrens/fshawksbill.html

• Hawksbill Incredible Journey: The Nature Conservancy http://www.nature.org/magazine/fall2002/turtles/

Hawksbill Sea Turtle Conservation

Populations Estimates for Areas with Major Hawksbill Colonies in the Pacific Ocean

Threats

Tortoiseshell objects such as combs, jewelry, furniture decoration and collectables are typically made from Hawksbill sea turtle shells. The shell has been described as the “world’s fist plastic.” These products are still produced even though there is an international ban on trafficking them.

Turtle meat and eggs have provided as food to many inhabitants and cultures that surround the Pacific. Turtle meat is considered a delicacy in some countries. Commercial and subsidence harvesting are both contributing to the depletion of the populations. Sea turtles are prized for their ability to stay alive for long periods after they are captured. In areas where there is no refrigeration, sea turtles are highly sought after as a feast food.

Tools were made from the turtle bones. Some parts of the turtle were used to make medicine. Turtles have been and still are on some islands the focus of important religious or ceremonial practices.

Status

The hawksbill sea turtle is considered threatened with extinction in all its range. The International Union for the Conservation of Nature (IUCN) red Data Book considers the hawksbill as endangered. The Convention on International Trade in Endangered Species of Wildlife Fauna and Flora (CITES) considers hawksbill as most endangered. Hawksbill sea turtles are protected under the U.S. Endangered Species Act (ESA) for Pacific territories (Guam, American Samoa) and commonwealths (CNMI) of the United States and for certain independent states.

Some of the direct causes to the population decline of hawksbills are the increased access to remote nesting beaches by indigenous fishermen equipped with spear guns and motorboats, SCUBA and advanced fishing gear. The tortoiseshell trade continues in Southeast Asia and Indonesia and has received market pressures from Asia.  In 1994 the once lucrative Japanese markets were closed.

Hawksbill Sea Turtle Behaviour

Diet and Life Cycle

Hawksbills eat sponges and other invertebrates found on coral reefs, which is likely why hawksbills are the most exclusively tropical of all sea turtles.

Females come ashore on nesting beaches every 2 to 5 years. After digging a nesting pit, they deposit up to 180 eggs. The eggs hatch in about 60 days, then the tiny hatchlings make their way to the beach and swim for up to three days to the relative safety of deep water, where they drift for years. Upon reaching a size of 8 to 12 inches, they return to shallower water, where they spend many years foraging and growing. At sexual maturity, both the male and the female return to the area where they were born to mate and begin the cycle again. Females lay from 2 to 4 clutches of eggs at two-week intervals before returning to their feeding grounds.

Foraging populations in the ocean do not always reflect the potential for nesting on adjacent beaches. Juveniles in their foraging habitat and adult females on their foraging home range may be from the same genetic stock but are likely to be geographically distant from each other and their natal beach. Further research with tagging and genetic surveys is needed to determine the relatedness of proximal groups in the foraging and nesting sea turtles. 

Hawksbill Sea Turtle Science

References

Animal Diversity Web. University of Michigan Museum of Zoology 2006. http://animaldiversity.ummz.umich.edu/site/accounts/information/Eretmochelys_imbricata.html

Busch Entertainment Corporation. Sea turtle Distribution and Habitat. SeaWorld/Busch Gardens ANIMALS. http://www.seaworld.org/animal-info/info-books/sea-turtle/habitat-&-distribution.htm (July 2007).

Incredible Journey: Hawksbill Sea turtles, 2007. The Nature Conservancy http://www.nature.org/magazine/fall2002/turtles/ (July 2007)

Recovery Plan for U.S. Pacific Populations of the U.S. Department of Commerce National Oceanic and Atmospheric Administration National Marine Fisheries Service U.S. Department of the Interior U.S. Fish and Wildlife Service Hawksbill Turtle (Eretmochelys imbricata), (July 2007) http://www.nmfs.noaa.gov/pr/pdfs/recovery/turtle_hawksbill_pacific.pdf

Spotila, Jim R. 2004. Seaturtles A Complete Guide to Their Biology, Behavior, and Conservation. The Johns Hopkins University Press, Baltimore, Maryland

Turtle Trax, July 2007. http://www.turtles.org/hawksd.htm

 Hawksbill Sea Turtle Photos

 Hawksbill Sea Turtle Photo Courtesy Dave Gibson. Used with permission.