Information

Turtles in the Hawaiian Islands

Sea turtles have graced our oceans for more than 75 million years. These ancient reptiles are among the most fascinating of all marine inhabitants. Here in Hawaii, three species of sea turtles are considered native: the green (Honu), the hawksbill (Honu’ea) and the leatherback. Two other species, the loggerhead and the olive ridley, are sometimes observed in Hawaiian waters.

The Hawaiian green sea turtle (Chelonia mydas) is the most common sea turtle in Hawaiian waters. It feeds on marine plants in shallow coastal waters throughout the Islands. Green sea turtles are primarily vegetarian and eat limu (algae) growing underwater on coral reefs and rocks in shallow waters. The upper shell (carapace) of the adult is dark with olive or gold flecks. Green turtles received their name from the color of their body fat. The honu grows to an adult breeding size of 200 pounds or more. Every 2-5 years, the adult Honu migrates hundreds of miles to mate and nest in the Northwestern Hawaiian Islands at isolated French Frigate Shoals.

Small numbers of the rare Hawksbill (Honu’ea) are found around the islands of Oahu, Molokai, Maui and Hawaii, where a few females have nested in recent years. Mature Hawksbills measure about three feet long and weigh up to 200 pounds. Hawksbills use their long, narrow beaks to probe for food. They feed on invertebrates, including sponges that are toxic to most other animals. The meat of the Honue’ea is poisonous to humans.

The Leatherback (Dermochelys Coriacea) is the world’s largest turtle and can grow up to eight feet long and weigh 2000 pounds. Leatherback turtles are seen in Hawaii’s deep offshore waters, where they feed on jellyfish and other invertebrates. Leatherbacks do not normally nest on Hawaii’s beaches, although a rare nesting was documented on Lanai in 1977. The Leatherback is the only sea turtle that lacks a hard shell. Fortunately, the laws in place to protect these marine species are effective and we are seeing an increase in the once dwindling numbers.

Did You Know?

The Hawaiian Green Sea Turtle…

  • is called “honu” in the Hawaiian language.
  • is a reptile and, hence, is ectothermic (cold blooded).
  • is a threatened species and is protected under the Federal Endangered Species Act and Hawaii state law.
  • has a shell (or carapace) that is made of many thin layers of keratin (similar to human finger nails) and can grow to 40” long or more. Its body can weight more than 400 lbs.
  • has a life expectancy of between 70 and 80+ years.
  • can swim in short bursts up to 20 mph.
  • feeds primarily on algae, seaweed and sea grass (“limu” in Hawaiian) as an adult.
  • does not have teeth, but does have a serrated lower jaw for tearing algae from rocks. It can inflict a serious bite!
  • has excellent underwater vision and can distinguish colors (its favorite is orange). On land they are nearsighted because the shape of their lenses are adapted for seeing underwater. It also has an acute sense of smell.
  • has no external ears but can hear low frequency sounds underwater as a result of vibrations through its skull that are sensed by the inner ear. Hearing on land is poor but low frequency vibrations are sensed through its shell and backbone.
  • gets its name from the greenish color of its internal body fat.
  • breathes air and must surface to do so (every 4-9 minutes when active; every 2 to 4 hours when inactive).
  • is hypo-osmotic, able to drink sea water, excreting excess salt through special salt glands near the eyes.
  • is the only species of sea turtle that basks on the beach to raise its body temperature and avoid predators.
  • is primarily preyed upon by large Tiger Sharks.
  • becomes reproductively mature around age 25-35 years old. Only at that point can males, having much longer and thicker tails, be distinguished from females.

Here at Laniakea Beach…

  • turtles have been recorded as basking ashore since 1999. They can be found here year round, feeding on limu and getting warm on the beach. Late morning through early afternoon is the most frequent time turtles haul out onto the beach. Marine scientists believe the honu come here for the abundance of food and the safety of the cove.
  • during the past 2 years, we have been tracking 20 turtles (5 males, 8 females, 5 sub-adults and 2 juveniles) basking at Laniakea. 
  • scientists periodically place satellite tags and time-depth recorders on the shells of the turtles. These devices provide insight into the movements, exposure to potential hazards at sea, and activity while under the water of the honu as they travel around in the ocean. One of our honu (Hiwahiwa) has been recorded as diving to a depth of 570 feet (173.7 meters).
  • all the honu have been given Hawaiian names; some also have English nicknames.

SHOW TURTLES ALOHA!
State and Federal laws prohibit harassment of sea turtles.
Observe sea turtles from a distance of not less than 10 feet (3 meters).
Do NOT touch, feed, harass or tease sea turtles.

Viewing Hawai'i Wildlife

Ocean recreation in Hawai'i can include encounters with marine wildlife. For their protection and your safety, view them responsibly!

Sea turtles, monk seals, dolphins and whales are wild animals and protected under state and federal laws.

Responsible Viewing

  • View from a distance. Use binoculars or your camera's zoom for a close up.
  • Do not disturb sea turtles or monk seals sleeping on the beach.
  • Never touch, chase, or feed. Animals are wild, unpredictable and protected.
  • Limit viewing time to a few minutes.
  • Never swim with spinner dolphins - they rest and nurture their young during the day.
  • View dolphins and whales from a boat or from shore.

Viewing Distances

  • Sea Turtles: View from at least 10 feet (3 meters) - on land and in water.
  • Hawaiian monk seals: Stay behind any signs or barriers. Stay back 50 feet (15 meters), if no barriers.
  • Dolphins: Stay back at least 50 yeards (45 meters).
  • Humpback whales: Do not approach within 100 yards - federal law.

Turtle Migration

When honu mature between the ages of 25-35 years, they begin to have the urge to breed. They leave their home reefs and swim to their birthplace for mating and nesting.

Between mid-March and mid-May, Laniakea honu begin their nesting migration to the Northwest Hawaiian Islands. Most honu prefer East Island of the French Frigate Shoals. Not every mature honu will migrate, and the annual cycle of migration for a particular honu is irregular and unpredictable. Most wait from two to four years between nesting migrations, but there are exceptions.

NOAA has tagged all of the adult honu basking at Laniakea with an ID chip so they can be identified both at their Laniakea foraging ground as well as at their nesting ground in the French Frigate Shoals. Over the years some honu have been tagged temporarily with a Time Depth Recorder (TDR), and some have been tagged with a satellite GPS. The TDR has provided data about the turtles’ dive depths, dive durations, ascent and descent rates, bottom time, and behavioral variables. The satellite tag provides data about migration routes.

The chart below tracked the 2010 migration of L-2, Hiwahiwa, when she made her second migration to East Island at the French Frigate Shoals. Hiwahiwa made a third migration in 2017 but had no tracking devices affixed to her carapace. 

map_12

All maps and data provided by:

NOAA, National Marine Fisheries Service
Pacific Islands Fisheries Science Center

Links to current Sea Turtle Conservation News

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