Chelonia mydas (Linnaeus, 1758)
Family: Cheloniidae Green Sea Turtle Status Indigenous Description: The green sea turtle is a large species reaching up 153 cm in carapace length. The shell is “heart shaped” and the posterior margin in serrated. The skin of the head neck and flippers is generally a shade of brown to dark grey while the carapace itself is generally darker and is often mottled or patterned with irregular lines (Ernst and Barbour 1989). In the Mariana Islands it is most likely to be confused with the hawksbill sea turtle which is smaller, has a “tortoise shell” pattern on the carapace and a distinct beak. Biology: Chelonia mydas is predominantly an herbivore feeding mostly on various sea grasses but also occasionally on other plants, algae, mollusks, crustaceans, sponges, and jellyfish (Ernst and Barbour 1989). It takes at least 25 years for females to reach maturity (NMFS & USFS 1998a) at which point a females will nest every 2-3 years (Ernst and Barbour 1989). Nesting occurs at night at which time females come ashore, dig a nest and deposits between 12 and 238 eggs. Eggs generally incubate for 45-60 days before hatching. (Earnst and Barbour 1989) Juveniles may not emerge from the nest until up to three days post hatching and invariably do so at night (NMFS & USFS 1998). The incubation temperature largely determines the sex of the juveniles with cool nests producing mostly males and warm nests producing mostly females (Ernst and Barbour 1989). The pacific population is considered threatened under the U.S. Endangered Species Act. The IUCN considers the green sea turtle endangered citing “extensive sub-population declines in all major ocean basins over the last three generations as a result of overexploitation of eggs and adult females at nesting beaches, juveniles and adults in foraging areas, and, to a lesser extent, incidental mortality relating to marine fisheries and degredation of marine and nesting habitats” (iucnredlist.org accessed 18 Feb 2013)” In the Mariana Islands the greatest threats to green sea turtles are directed take (harvest), increased human presence, coastal construction, nest predation, and sea-grass/reef degradation (FWS 1997). Distribution: The green sea turtle is found throughout the tropical waters of the Atlantic, Pacific, and Indian Oceans (Ernst and Barbour 1989). This turtle is the most frequently seen sea turtle in the region. Kolinski et. al. (2004) predicted that between 1000 and 2000 Chelonia inhabit the waters of the CNMI, though most are juveniles and sub-adults. Green sea turtles have been observed in the Marianas in every month of the year but seems particularly common between December and February and May to June (NMFS & USFS 1998a). In Guam, nesting occurs at low levels. Fewer than ten individuals nest on Saipan, Tinian, and Rota each year. It is unknown whether green sea turtles nest on other islands of the Marianas and to what extent (NMFS & USFS 1998). Ernst C. H. and R.W. Barbour. 1989. Turtles of the World. Smithsonian Institute. 313 pp. NMFS & USFWS. 1998. Recovery Plan for U.S. Pacific Populations of the Green Turtle (Chelonia mydas). National Marine Fisheries Service, Silver Spring, MD. 84 pp. |