Learn & Explore/Species/Sea Turtles/Hawksbill Sea Turtle
Hawksbill Sea Turtle
Hawaiian name: Honu ʻea (or ʻea)
Scientific name: Eretmochelys imbricata
Description and Natural History
- Medium-sized marine turtle with a hawk-like beak.
- Adults can be about 3 feet in shell length and weigh 250 pounds (a little smaller than green sea turtles).
- Shell has a “tortoise-shell” pattern, historically prized for making jewelry, strong fishing hooks, and other ornamental objects.
- Heavy hunting caused population decline.
- In Hawai‘i, called honu‘ea or ‘ea.
- Studies suggest hawksbills in Hawai‘i represent a distinct genetic stock and nesting population, but a distinct population segment has not yet been established for these turtles.
The Hawksbill Sea Turtle
QUICK FACTS
LENGTH
About 3 feet
LIFESPAN
Up to 50+ years
THREATS
Climate Change & Habitat Loss, Predation, Fishing Gear & Marine Debris, Illegal Harvest & Other Human Impacts
Status and Protection
Hawksbill sea turtles are protected federally by the ESA and locally by HRS Chapter 195D and HAR 13-124. Because distinct population segments have not been established for this species, hawksbills are listed as endangered throughout their global range under the ESA. The IUCN lists them globally as critically endangered meaning they face an extremely high risk of extinction. Like green sea turtles, the state shares the management for hawksbill turtles within state jurisdiction with the USFWS and NOAA NMFS. Hawksbills are rare in Hawaiʻi, compared to the green sea turtle, which outnumbers hawksbills by about 100 to one [10].
Diet and Habitat
- Foraging sites in Hawai‘i are along the eastern (Hāmākua) coast of Hawai‘i island and the waters of west Maui.
- Diet varies but commonly includes marine sponges, invertebrates (like crabs and fireworms), and algae.
- Hawksbill meat can be harmful to humans because they consume sponges, making the meat potentially toxic and capable of causing disease or even death.
- Hunting hawksbills for consumption has been illegal since 1973.
Reproduction and Nesting
- Sexual maturity: Hawksbill sea turtles are estimated to reach sexual maturity between 20–35 years.
- Nesting in Hawai‘i: Nesting appears to be exclusive to the Main Hawaiian Islands, primarily along the southeast shoreline of the island of Hawai‘i (Kaʻū coastline), with a smaller number of nests on isolated beaches of Maui, Moloka‘i, Lāna‘i, and Kauaʻi. About 20–25 females nest annually.
- Nesting season: May–December.
- Clutch size: Approximately 130–160 eggs.
- Hatchlings: Generally emerge after about two months of incubation and head to the ocean, where little is known about their pelagic, early-life stage.
- Temperature-dependent sex determination: Cooler incubation temperatures produce males, while warmer temperatures produce females.
Threats
Predation
- Eggs and hatchlings in the Main Hawaiian Islands face threats from non-native animals such as cats, dogs, mongooses, rats, and pigs.
- Dense non-native vegetation can block hatchlings from emerging.
Fishing Gear/Marine Debris Entanglement
- Hawksbills are vulnerable to entanglement in debris or discarded fishing gear, including fishing lines, hooks, and nets, which can prevent them from surfacing to breathe, swimming effectively, avoiding predators, feeding, or reproducing.
- Ocean currents concentrate debris, increasing risk.
- Fishing lines, hooks, and nets pose the greatest danger.
- Public tip: Remove fishing gear or debris from shorelines to help save turtles.
Climate Change and Habitat Loss
- Loss of beach area from coastal erosion and sea-level rise limits nesting space for Hawksbills in Hawai‘i.
- Coral bleaching and increased ocean acidity reduce the availability of marine sponges and other invertebrates that Hawksbills feed on.
- Warming temperatures may skew sex ratios due to temperature-dependent sex determination, potentially producing more females than males and risking future population declines.
Intentional Take and Accidental Bycatch
- Hawksbill turtles in Hawai‘i are still threatened by intentional killing, harvesting, harassment, and other disturbances despite federal and state protection.
- Even non-lethal interactions like touching, feeding, or approaching turtles, as well as recreational shore-based fisheries, can cause stress, injury, entanglement, or death.
Literature Cited
1. NOAA Fisheries. (2023, July). Green Turtle.
2. Maui Ocean Center. (2023). Hawaiian Green Sea Turtle.
3. Seminoff, J.A et al. (1970, January). Status Review of the green turtle (Chelonia mydas) under the Endangered Species Act.
4. NOAA Fisheries. (2019, August). There and Back Again: A Turtle Biologist’s Tale.
5. NOAA Fisheries. (2017, April). What causes a sea turtle to be born male or female?
6. NOAA Fisheries. (2015, June). A sea turtle listicle. Fascinating Facts.
7. NOAA Fisheries. (2021, January). Fibropapillomatosis and Sea Turtles – Frequently Asked Questions.
8. NOAA Fisheries. (2023, October). Hawksbill Turtle.
9. Gaos, Alexander R. et al. (2020, June). Conservation Genetics Hawaiian hawksbills: a distinct and isolated nesting colony in the Central North Pacific Ocean revealed by mitochondrial DNA.
10. NOAA Fisheries. (2020, July). Hawksbill sea turtles are truly Hawai’i locals.
See Another Turtle
Green Sea Turtle
Hawaiian name: Honu
Scientific name: Chelonia mydas