The Hawaiian green sea turtle (Chelonia mydas) is named for the greenish color of its body fat. Adult green sea turtles average 3 to 4 feet in length and 400 pounds in weight. The color of their carapace (shell) varies from black to brown or dark green. Green sea turtles can live up to 80 years of age. They live near coral reefs and rocky shorelines where algae is plentiful.

Diet
Adult green sea turtles are herbivores, and their diet consists mainly of seagrass and macro algae. Juvenile green sea turtles are omnivorous; their diet consists of plankton, fish eggs, jellyfish and other invertebrates.

Reproduction
Hawaiian green sea turtles reach breeding age at approximately 25 years old. Females return to the same beach where they hatched to lay their eggs. Ninety percent of all Hawaiian green sea turtles breed and nest on the sandy islands of the French Frigate Shoals. Thirty years ago, George Balaz, Hawaii's green sea turtle expert, counted only 67 nesting females at East Island, French Frigate Shoals. At that time, turtles were being hunted for their meat, shell, and eggs. Now the turtles are protected by law and their numbers are steadily increasing. A recent count of nesting turtles on East Island found 467 nesting females in a season -- a nearly 600 percent increase.

Nesting occurs from late April through September with a peak in July. Adult turtles migrate from their feeding grounds along the main Hawaiian Islands and travel over 600 miles to the French Frigate Shoals. While males appear to migrate every year, females migrate and breed only every 2-4 years. Copulation occurs in shallow waters near nesting beaches. Each female may lay 1-5 egg clutches approximately every 10-14 days. During the cool of the night, the female turtle pulls herself up the beach using her front flippers. Upon reaching the high-tide mark, she uses her front flippers to dig a wide pit, and then carefully digs an egg chamber using her rear flippers. She lays approximately 100 leathery-skinned ping-pong-ball-sized eggs in the chamber. The female turtle covers the eggs carefully and then flings sand over the entire nest, disguising the location. Once finished, the female turtle returns to the sea, leaving her eggs and future hatchlings to fend for themselves.

Hatchling sea turtles begin to emerge in July after about 60 days of incubation. The two-inch hatchlings emerge from a nest en masse, since one hatchling is not strong enough to dig out of the nest by itself. They emerge from the nest at night and head for the water immediately. At this time, ghost crabs and reef fish pose a primary threat to the hatchlings. Only a few baby turtles from each nest will survive into adulthood.

Population Status and Conservation
Tiger sharks are the primary predator for large sea turtles. Turtles also become entangled in marine debris and nets, or ingest plastics and other marine debris. Since the 1980s, Hawaiian green sea turtles have been afflicted with a type of tumor called fibropapillomatosis (FP). In certain areas of the main Hawaiian Islands, up to 50 % of the turtles have FP. Currently, scientists believe FP is the most common cause of death in free-ranging green turtles in Hawaii.

Until recently, humans were killing Hawaiian green sea turtles for its meat, shell, and eggs. The turtle population dwindled to perilously low numbers. As a result, the Hawaiian population of the green turtle was listed as threatened under the U.S. Endangered Species Act in 1978. Now it is illegal to kill, capture, or harass sea turtles. The turtle population is recovering and it is estimated that Hawaii now has as many as 35,000 mature green sea turtles and perhaps 250,000 juveniles age 6 or under.

Because sea turtles live at sea and nest on land, responsibility for their conservation is shared between the National Marine Fisheries Service and the U.S. Fish and Wildlife Service. If you are in Hawaii and see a turtle that has been killed or harmed, you can call the National Marine Fisheries Service at 800-853-1964.