Scientists: Rise in sea turtle population unrelated to reduced tourism

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A honu (green sea turtle) swims over the reef in Kahaluu Bay. (Chelsea Jensen/West Hawaii Today)
A honu (green sea turtle) swims over the reef in Kahaluu Bay. (Chelsea Jensen/West Hawaii Today)
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While tourism in Hawaii has declined during the COVID-19 pandemic, sea turtle populations have increased — but scientists say the two are unrelated.

The global decrease in travel throughout 2020 has led to speculation that lockdowns and quarantines have allowed the environment to partially recover from human activity. But while endangered sea turtle populations have seen a rebound in Hawaii this year, experts caution against correlating the two factors.

“It’s true that there has been a large increase in the number of green sea turtle nests,” said Ryan Jenkinson, head of the state Department of Land and Natural Resources’ Aquatic Resources Division Protected Species Program. “But that’s totally independent of what’s happening with COVID.”

Sea turtles, Jenkinson said, do not reproduce so quickly that a single summer can reverse their declining population, and there is not enough data to suggest what impact, if any, the global lockdown has had on their population.

While Danielle Bass, sustainability coordinator for the state’s Office of Planning, told the state House of Representatives Tuesday that green sea turtle nests on Oahu have been particularly successful over the summer — Marine Corps Base Hawaii reported more than 13 nests on Bellows Beach on Oahu in June, and that 95% of hatchlings survived — Jenkinson said it would be hasty to attribute that success to COVID impacts.

“Turtles don’t make annual schedules,” Jenkinson said.

Jenkinson explained that green sea turtles tend to nest where they themselves hatched, but if that site is unavailable — for example, if there are too many people on a beach between the ocean and the nesting site — they simply find other sites. A high number of turtle nests on one beach, therefore, does not indicate that the number of sea turtles has increased, merely that a greater-than-average number of turtles chose that beach to nest, for whatever reason.

Jenkinson pointed out that certain nesting sites on the minor Hawaiian islands and reefs have been irrevocably lost to climate change, necessitating a search for other sites on the larger islands.

Alex Gaos, research biologist for the National Oceanic and Atmospheric Administration’s Pacific Fisheries Science Center, said a decrease in human activity could potentially benefit specific sea turtle nests — “there could be fewer lights to confuse the hatchlings, or maybe there’s fewer drivers running over nests or something,” he said — he pointed out that the lack of human activity could just as easily create false positives.

“If there’s fewer people on the beach, that means hatchlings’ tracks couldn’t be obscured as much, so it might look like there’s more of them,” Gaos said.

In short, Jenkinson said, any increase in the green sea turtle population around Hawaii this year is more likely attributable to years of conservation work dedicated to the recovery of the endangered species, rather than a single summer with fewer tourists than average.

As for hawksbill sea turtles, the critically endangered species also found in Hawaii’s waters, even less can be concluded. Jenkinson said the DLNR researchers monitoring hawksbill populations were unable to make observations this year — ironically, because of COVID.

Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.