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Scientific name: Chelonia mydas
Pacific Island names: honu (Hawaiian), haagan (Chamorran) laumei ena'ena (Samoan)
Stock Assessment / Estimated Breeding Population
Despite an overall declining trend globally, green turtle population growth rates are variable among nesting populations and regions. The Hawaiian green turtle population is actually increasing in abundance and has increased 53% over the last 25 years. Low levels of green turtle nesting also occur in Guam, American Samoa, the Northern Mariana Islands, and other U.S. island territories. Information on population trends for green turtles in the region other than the Hawaiian stock is limited.
- Endangered Species Act (ESA)
- Hawaii state law
Green turtles are found throughout the world, occurring primarily in tropical, and to a lesser extent, subtropical waters. The Hawaiian green turtle is genetically distinct from the other green sea turtle populations, nesting primarily in the French Frigate Shoals of the Northwestern Hawaiian Islands and feeding in the coastal areas of the main Hawaiian Islands. This species was in a steep decline as of the 1970s because of direct harvest of both turtles and eggs by humans. The population has grown steadily over the last thirty years after protection began in 1978. Greens are the most common species of sea turtle found in Hawaiian waters.
- A typical adult green turtle has a carapace length of 40 inches and can weigh from 200-500 lbs.
- Green turtles exhibit counter-shading with a carapace (shell) that can range from olive brown to black in color and a much lighter yellow plastron (underside).
- Green turtles have five vertebral scutes running down the middle of their shell and four costal scutes on each side. (Unlike the hawksbill turtle which has the same number of scutes, the scutes of the green turtle do not overlap).
- Another distinguishing characteristic of this species is their two large prefrontal scales located between the eyes.
Adults primarily eat algae. Over 275 different species of seaweed have been found in the stomachs of Hawaiian green turtles. In order to deal with this diet of roughage, green turtles have microflora living in their large intestine that help breakdown the cellulose that is otherwise undigestible. Other food items they consume in lesser amounts include jellyfish, salps, mollusks, sponges, and tubeworms. East Pacific green turtles tend to eat more animal prey than other populations.
The lifespan for sea turtles in generally unknown but for green turtles is thought to be around 60-70 years.
Green turtles become sexually mature at 25-35 years, and some may be as old as 40 before being able to reproduce.
The length of reproductivity has been estimated to range from 17 to 23 years.
They return to nesting beaches to lay eggs every two to three years and will deposit three to six clutches per nesting season with an average of twelve days in between. Each clutch consists of about 100 eggs that will incubate for 60 days.
More than 90% of the Hawaiian population of green turtles nests at French Frigate Shoals in the Northwestern Hawaiian Islands. They migrate to feed mainly in the coastal areas of the Main Hawaiian Islands. Limited nesting locations and important coastal foraging areas for green turtles are found throughout the Pacific islands.
Local Cultural Significance
Historically, green turtles have played a large role in Polynesian and Micronesian cultures. In addition to being used as a food source, native peoples all over the Pacific utilized all parts of the turtle making tools and jewelry out of the bones, and containers and utensils out of the carapace. Turtle fat was sometimes used for medicinal purposes to treat burns and other skin disorders. Turtles were often considered the property of the tribal chief and their utilization was regulated by some form of island council.
In the Hawaiian Islands, there were families that considered the green turtle a personal family deity or aumakua, not to be eaten or harmed. One legendary example is the story from the Big Island of Hawaii of the turtle named Kauila. She was believed to be able to change at will into human form to watch over the village children playing near the shore. Artistic elements of green turtles have also been featured prominently in some cultures of the region, such as petroglyphs and tattoo designs.
- Disease - Disease is considered the primary threat to green turtles in Hawaii. Fibropapillomatosis causes tumor growth on the exposed soft tissue including flippers, head, and neck areas. While the tumors do not appear to be accompanied by any other symptoms or negative effects, their location could be detrimental to the survival of an individual. For example, if a tumor obstructs a turtle's mouth or eyes enough, it may starve due to inability to locate and/or ingest food. Tumors around the eyes may also impair vision so that a turtle's ability to avoid predators is reduced.
- Harvest - In a American Samoa, Guam and the Commonwealth of the Marianas Islands, direct harvest remains a serious threat to green turtle populations. Hawaiian green turtles have been sucessfully protected from these threats for over 25 years and their population growth is evidence of the success of such protection.
- Incidental take in fisheries
- Indestions of marine debris
- Habitat loss
- Nest and hatchling predation
Current Management Issues
On February 16, 2012, a petition to classify the green sea turtle (Chelonia midas) in Hawaii as a distinct population segment (DPS) and delist the DPS under the ESA was received from the Association of Hawaiian Civic Clubs.
On August 1, 2012, NOAA Fisheries made a positive 90-day finding (77 FR 45571), determining that the petitioned action may be warranted. A comprehensive status review is underway to inform the 12-month finding.
For more information on the green sea turtle, please see the NOAA Fisheries Office of Protected Resources’ green sea turtle page
Frequently Asked Questions (FAQ) about the natural history and ecology of Hawaiian green sea turtles
- Hawaiian Green Turtle - Life History (Feb 2011, pdf 265.4 kB)
- Hawaiian Green Turtle - Nesting (Feb 2011, pdf 314.5 kB)
Important Phone Numbers
If you encounter an entangled or stranded sea turtle, please call: (808) 725-5730 or view see Marine Turtle Stranding Contact Information for more numbers.