Green Turtle

Chelonia mydas

The top shell (carapace) is smooth with shades of black, gray, green, brown, and yellow; their bottom shell (plastron) is yellowish white. Green turtles are the largest of all the hard-shelled sea turtles, but have a comparatively small head.

Though subadults and adults are common, the number of green turtles living and foraging within Midway's lagoon is undetermined at this time. Many of Midway's turtles have been tagged, providing a useful tool for monitoring the population.

Adults migrate from foraging grounds throughout the Hawaiian Islands to breeding grounds. Males appear to migrate every year, arriving ahead of the females. Females return to the same beaches where they were born every 2-4 years to lay eggs, generally in the summer months. Disturbing turtles basking on the beach may result in them avoiding those beaches as they do not feel "safe".

Ninety percent of all Hawaiian green turtles breed and nest at French Frigate Shoals (FFS), a cluster of sand islets located at the approximate midpoint of the Hawaiian Archipelago. Nesting at FFS occurs from late April through September with a peak in June-July. Each female deposits 1-5 egg clutches (average 1-2) at 11-18 day intervals.

Hatchlings emerge en-masse, usually at night, from a sandy 2-ft deep nest after about 60 days. After emerging from the nest, hatchlings swim to offshore areas, where they are believed to live for several years, feeding close to the surface on a variety of pelagic plants and animals. Once the juveniles reach a certain age/size range, they leave the pelagic habitat and travel to nearshore foraging grounds.

The principal cause of the historical, worldwide decline of the green turtle is long-term harvest of eggs and adults on nesting beaches and juveniles and adults on feeding grounds. These harvests continue in some areas of the world and compromise efforts to recover this species. Incidental capture in fishing gear, primarily in gillnets, but also in trawls, traps and pots, longlines, and dredges is a serious ongoing source of mortality that also adversely affects the species' recovery. Green turtles are also threatened, in some areas of the world, by a disease known as fibropapillomatosis.

In the U.S., NOAA Fisheries and the U.S. Fish and Wildlife Service (USFWS) have joint jurisdiction for green turtles, with NOAA having the lead in the marine environment and USFWS having the lead on the nesting beaches. Both federal agencies, and a number of state agencies, have promulgated regulations to eliminate or reduce threats to sea turtles.

Facts About Green Turtle

Adult green turtles are unique among sea turtles in that they eat only plants; they are herbivorous, feeding primarily on seagrasses and algae. This diet is thought to give them greenish-colored fat, from which they take their name.
Life Span
Unknown, but sexual maturity occurs anywhere between 20-50 years
Adults: length 1 m (3 ft), weight 135-160 kg (300-350 lbs); hatchlings: length 50 mm (2 in), weight 25 g (0.05 lbs)