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Hurricanes and rising tides are moving turtles back to main Hawaiian Islands

One way the project is tracking individual turtles is through radio transmitters attached to the turtle's shell.
Lindsey Bull
/
NOAA Fisheries
File - Turtles huddle up with about 40 other adult turtles, basking on the remnants of Trig Island. Trig was once one of the main nesting beaches for Hawai'i’s green sea turtles. Now, waves lap at their hind flippers, even at low tide.

Sea turtles are returning to nest on the main Hawaiian Islands for the first time in decades.

The U.S. Fish and Wildlife Service reported that about one or two turtle nests appear on Oʻahu per year. In 2020, about 57 nests were accounted for and scientists believe that the nests will continue to increase.

They say that due to the destruction of the Northwestern Hawaiian Islands from Hurricane Walaka in 2018, turtles are instead beginning to find their way to the main Hawaiian islands.

Turtles nest on the island they are born. Lalo (Kānemilohaʻi/French Frigate Shoals) was the most popular nesting ground for honu before Hurricane Walaka and rising sea levels made it difficult for the reptiles to return.

A turtle deposits a clutch of eggs and scientists add a tiny data logger to monitor the nest temperature throughout incubation. These data will allow scientists to predict the sex ratio of hatchlings produced based on the temperatures recorded during the second trimester of incubation.
Marylou Staman
/
NOAA Fisheries
A turtle deposits a clutch of eggs and scientists add a tiny data logger to monitor the nest temperature throughout incubation. These data will allow scientists to predict the sex ratio of hatchlings produced based on the temperatures recorded during the second trimester of incubation.

Sea turtles used to nest throughout the Hawaiian archipelago until commercial fishing reduced their populations until their only nesting colony was on Lalo. Harvesting turtles became illegal in 1978 when they received protection under the Endangered Species Act.

FWS coastal program coordinator Sheldon Plentovich said there are several hypotheses as to why the sea turtles are choosing to nest on the main Hawaiian Islands and specifically on Oʻahu.

"Some of (Oʻahu's) historical nesting grounds are starting to support nesting sea turtles again," said Plentovich.

As the turtles find their way to the main Hawaiian Islands to nest, Plentovich said residents must be cautious about turning on their lights after dark.

"People don't know how easily baby turtles are disoriented by light. For example two years ago at James Campbell National Wildlife Refuge, which is quite a dark place, we had several nests up on the sand dunes and almost all the hatchlings went mauka, and we went out there at night to try to figure out what was going on," Pentovich said.

"And there was a single unshielded light on the ridge line by the wind farm miles away, and that single unshielded light caused the deaths of over 100 hatchling sea turtles," Plentovich told HPR.

Properties close to the beach may consider purchasing turtle-friendly lights.

Turtles are less attracted to lights with longer wavelengths of no less than 560 nanometers since they emit warmer colors like amber. Plentovich asks bystanders to keep the lights low to the ground and surround it with the shield.

Additionally, FWS warns against driving all-terrain vehicles on the beach. Driving on the beach is not only illegal in most areas, but the tire ruts can trap the hatchlings.

The public can also distinguish the difference between an adult turtle's basking and nesting behavior to know if there are any turtle eggs to watch out for.

Basking sea turtles typically lie closer to the water. They move the sand with their front flippers and sleep on the beach.

Nesting sea turtles dig with their rear flippers. They typically lay their eggs at night or under coastal vegetation away from the high tide line.

If you see a sea turtle, keep a distance of more than 10 feet. Do not touch, feed or chase them. If the turtle is nesting, call the NOAA Fisheries Marine Wildlife Hotline at 1-888-256-9840.

Zoe Dym was a news producer at Hawaiʻi Public Radio.
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