Hawksbill turtle (Eretmochelys imbricata)

Hawksbill turtle (Eretmochelys imbricata)

The has a distinctly narrow heart-shaped shell, and often has a distinct vertebral keel.

Also known as: Hawksbill Turtle

Local Names: Taku

Description

The Hawksbill turtle has a distinctly narrow heart-shaped shell, and often has a distinct vertebral keel. Like the Green turtles, Chelonia mydas, the Hawksbill turtles belong to the family of hard-shelled turtles, Cheloniidae. The average length of an adult Hawksbill turtle’s shell or carapace is 70cm, and can grow up to 1m in length. The carapace is dark brown in colour with mottled lighter and darker patterning. The scutes are strongly overlapping in adults, and not in hatchlings and juveniles. The edge of the carapace is serrated posteriorly. On the carapace are 5 vertebral plates, and 4 inframarginal plates on the bridge and four costal plates on each side of the carapace.

Hawksbill turtles typically have a small head, distinguished by the hooked, parrot-like beak of the projecting upper jaw, and the two pairs of prefrontal scales on the top of the head. By comparison, the Green turtles do not have a hooked beak jaw, and have only one pair of prefrontal scales on the top of the head. The head is dark brown to black in colour.

For identification of the turtles, you may refer to the following website:

Sea Turtle ID Sheet

Male hawksbill turtles have long thick tails that extend beyond the posterior carapace margin; tails of females on the other hand, do not pass the margin. The dorsal surface of the Hawksbill turtle is olive-green or brown in colour, variegated with reddish brown, dark brown and black. The ventral surface is whitish. Hatchlings have a blackish dorsal surface and a dark ventral surface.

 Hawksbill turtle (Eretmochelys imbricata)

Hawksbill turtle (Eretmochelys imbricata)

 Hawksbill turtle - Eretmochelys imbricata map

Hawksbill turtle - Eretmochelys imbricata map

Distribution

Hawksbill turtles have a tropical and subtropical Indian, Pacific and Atlantic Ocean distribution. They are the most common turtle species in Fiji and have been recorded from much of the Fiji waters; however, the nesting sites are now restricted to small islets and cays. These are: Namena-lailai, the offshore islands off in Macuata, Laucala Island, Leleuvia Island, Tavarua, Yadua island, the sacred island in Rotuma, Makuluva, Makogai, Koro, Gau, Nananu-i-ra, most Mamanuca islands, the Yasawas, Heemskereq Reef, Ringgold Reef and Qelelevu Atoll.

Habitat Ecology and Behaviour

Adult hawksbill turtles are primarily carnivorous, feeding on a variety of marine animals such as fish, crabs, various mollusks, certain species of sponges and jellyfish. They usually feed in the early morning or late afternoon, and are usually seen browsing and resting either on the reef or at the surface at other times of the day. Hawksbill turtles nest at least four times per breeding season; with 15-20 days between each nesting effort. They lay 150 or more eggs per clutch. Nesting seasons in Hawksbill turtles have been shown to occur every two to three years. Hawksbill turtles can live up to more than a hundred years; they have a very slow growth rate, and in its adult stage they have an average of 80.9 cm carapace (curved) length. Like the other turtles recorded from Fiji waters, Hawksbills are migratory; satellite tracking has shown that they can travel up to 1600 km.

Threats

It has been suggested that the commercialisation of the turtle trade in the 1800’s has led to the demise of the populations here in Fiji, and the Pacific. Thousands of turtles have been harvested for their meat and for their shells. The international turtle trade was already in existence in Fiji in 1840, when traders came in to buy turtle shells to be sold in Manila. In the 1940s, the trade of Hawksbill turtle shells was thriving, being used for toilet seats, cigarette cases and jewellery boxes. Between 1984 and 1989, more than 5, 000 Hawksbill turtles were killed in Fiji for export of the shell.

Conservation Status

The plight of the Hawksbill turtle in Fiji and the Pacific and the conservation efforts following echoes that of the other two turtles mentioned in this project: Green turtles and the Leatherback turtles. In the 1980s, there were 140 Hawksbill turtles found to be nesting on Namena-lala Island; between 1993 and 1994, this had decreased to 14; and rose again to 19 between 1994 and 1995.

The establishment of the Fiji Sea Turtle Working Group in 1997 (see the Green turtle species account) has led to much of the conservation efforts of turtles here in Fiji.

In 1998, there was a record of 2,000 to 3,000 Hawksbill turtles in the Fiji waters, of which only 120 to 150 were locally breeding populations. The turtles were sighted around the Astrolabe lagoon (Kadavu), Heemskereq and Ringgold Reef, Namena Island, Laucala Island, Nananu-i-ra, Tavarua, Yadua and Vatulele.

More recent data (MacKay, personal communication) suggests that probably 200-300 females nest annually in Fiji waters. There is on-going documentation on the current state of turtles nesting in Fiji by a USP graduate and Ministry of Fishery staff, Neema Nand. According to Dr. Mackay of the IMR, her research will undoubtedly update the status of Fiji’s nesting turtles.

Remarks and Cultural Significance

The plight of the Hawksbill turtle in Fiji and the Pacific and the conservation efforts following echoes that of the other two turtles mentioned in this project: Green turtles and the Leatherback turtles. In the 1980s, there were 140 Hawksbill turtles found to be nesting on Namena-lala Island; between 1993 and 1994, this had decreased to 14; and rose again to 19 between 1994 and 1995.

The establishment of the Fiji Sea Turtle Working Group in 1997 (see the Green turtle species account) has led to much of the conservation efforts of turtles here in Fiji.

In 1998, there was a record of 2,000 to 3,000 Hawksbill turtles in the Fiji waters, of which only 120 to 150 were locally breeding populations. The turtles were sighted around the Astrolabe lagoon (Kadavu), Heemskereq and Ringgold Reef, Namena Island, Laucala Island, Nananu-i-ra, Tavarua, Yadua and Vatulele.

More recent data (MacKay, personal communication) suggests that probably 200-300 females nest annually in Fiji waters. There is on-going documentation on the current state of turtles nesting in Fiji by a USP graduate and Ministry of Fishery staff, Neema Nand. According to Dr. Mackay of the IMR, her research will undoubtedly update the status of Fiji’s nesting turtles.

References

Boyle (1998);
Ernst et al (1994);
Guinea (1993);
Mackay, K. (personal communication);
McCoy (2000);
Sue (1996);
Wilkes (1845).

Front Page Photo: Joe Leqa