Hawaiian green sea turtles, or honu, are native to Hawaii. They are the largest hard-shelled sea turtle in the world, reaching lengths of four feet and weights over 300 pounds. Out of the seven types of sea turtle, the Hawaiian green sea turtle is the most common turtle in Hawaii.
The color of their carapace (upper shell) ranges from brown with yellow and light brown streaks to black. The color of their plastron (bottom shell) is a light yellow. As adults, honu mainly eat algae and sea grasses, which turn their fat layer green, giving them their common name.
With lungs two-thirds as long as their carapace, it is believed they can stay underwater for many hours depending on the animal’s size. The longest recorded downtime was five hours. Eyesight underwater is excellent while above water they are reported to be nearsighted.
Hawaiian Green Sea Turtle Educational Loan Program
In partnership with Sea Life Park Hawaii (SLPH), the sea turtles at Maui Ocean Center (MOC) are part of the Hawaiian Green Sea Turtle Educational Loan Program, authorized by the U.S. Fish and Wildlife Service (FWS) and conducted under scientific supervision by the National Marine Fisheries Service – Pacific Islands Fisheries Science Center.
This program is specifically designed as an educational outreach program geared towards education, conservation, and the enhancement of the public’s awareness of the oceans and its inhabitants. The juvenile turtles at MOC were hatched at SLPH on O‘ahu. SLPH is home to a colony of adult Hawaiian green sea turtles which produces approximately 200-800 hatchlings each year, most of which are released into the wild, except those kept at collaborating institutions to be released at a later date as juveniles.
When the juveniles reach the ages of 2-3 years, under the authority and approval of the U.S. FWS, they are released into Hawaiian waters at a location approved by the agency. SLPH replaces those turtles released with new hatchlings if available in order to maintain each facility’s educational display program.
Hawaiian Green Sea Turtle Reproduction
The Hawaiian green sea turtle typically reaches sexual maturity after reaching 20 years of age, with some turtles in a study over 40 before mating the first time. At this time, males grow long thick tails but females’ tails stay short. Females may mate every two years and after doing so, over ninety percent will swim from the main island chain westward to the French Frigate Shoals, a distance of nearly 600 miles (Maui to the shoals), to lay her eggs. According to George Balazs, this journey for a Maui female could take more than two months since they ‘island hop’, grazing on seaweed off each island along the way.
Upon reaching their destination, the females laboriously haul themselves out of the water getting as far away from the tide line as possible. They dig a pit called a nest chamber and lay an average of 75 to 100 eggs per nest digging as many as six nests in one season. Typically done in the early summer months, about two months later the hatchlings emerge. Sex is determined by temperature – the cooler the sand, the more males.
Life doesn’t come easily for small sea turtles. The first few years of their lives, also called “the lost years”, are spent roaming the open ocean or pelagic zone where it is believed they find mats of algae, seaweed, or debris for protection. With an omnivorous diet, they feed upon sea jellies, crustaceans, and fish. But the real challenge is making it to the open ocean as the sandy shorelines and shallow reefs pose a high threat. Animals like crabs, dogs, mongoose, and even people take these young hatchlings. Seabirds frequently spot them from the air and many species of fish prey on hatchlings. Juveniles return to their coastal grazing areas after five to ten years, where they mostly graze on seaweed (limu).
Significance in Hawaiian Culture
In old Hawaii, green sea turtles were thought to be the property of the ali‘i, or chiefs, and were sometimes raised in loko i‘a, or fishponds, according to Maui Ocean Center’s Hawaiian Cultural Advisor Kahu Dane Maxwell. The meat was eaten, bones used for ornaments or fishhooks, and shells used for containers. Some individuals or families did not take or consume honu, rather they were thought as family deities (aumākua) and were worshipped and cared for.
A Protected Species
All sea turtles are listed as endangered species in the United States, meaning it is a federal offense to harm, harass, or even touch a sea turtle. Whether the turtle is in the water or resting on a beach, any physical contact is prohibited. Current research in Hawaii shows the Hawaiian green turtle population is increasing since they have been protected by federal law.
*Due to the constant rotation of animals back to the ocean, the presence of any specific animal cannot be guaranteed.