With the newly expanded Papahanaumokuakea Marine National Monument taking center stage at the World Conservation Congress in Honolulu, a conservation group is warning of a “dangerous drop” in the number of nesting Hawaiian green sea turtles in the Northwest Hawaiian islands.

The Turtle Island Restoration Network on Tuesday pointed to new research from NOAA’s Marine Turtle Biology and Assessment Program that shows an 84 percent reduction of nests compared to last year and calling for action to reduce green sea turtle deaths.

“An 84 percent decline should trigger emergency actions to protect green sea turtles,” Turtle Island’s Peter Fugazzotto said in a news release. “No. 1 on that list should be reducing adult mortality from industrial fishing. With this recent information, we cannot afford the death of even one more green sea turtle.”

But National Oceanic and Atmospheric Administration scientists said they don’t believe the turtle species is in trouble. They said the sharp decline likely is a natural variation precipitated by El Nino.

“Of course, we’ll pay attention to what we see next year,” said Frank Parrish, director of the Protective Species Division of NOAA’s Pacific Islands Fisheries Science Center. “Being (an El Nino) year, we fully expected to have lower numbers.”

NOAA researchers monitored green sea turtles at French Frigate Shoals for more than two months this summer and counted only 88 nesting turtles compared to 492 last year.

Turtle Island last month released a report describing the impacts of sea-level rise on major sea turtle nesting beaches around the world, including French Frigate Shoals, where more than 90 percent of all Hawaiian green sea turtles nest.

The low-elevation atoll is extremely vulnerable due to sea-level rise. Already, one island, Whaleskate, a popular nesting site in the 1960s, is now submerged, according to the report.

Turtle Island is calling for the creation of a secondary nesting colony to spread the risk and for efforts to reduce the impact of longline fishing.

According to the California-based conservation group, an estimated five green sea turtles were killed by the Hawaii longline fishery in 2015 and an estimated five green sea turtles have already met the same fate in 2016.

“While researchers try to determine whether this nesting decline is related to a population decline, common sense dictates a precautionary approach,” Fugazzotto said. “That approach is one that greatly reduces the death of adult green sea turtles.”

But Parrish said this year’s low numbers probably have less to do with a population decline and more to do with the affects of a strong El Nino, in which warm waters in the equatorial Pacific change weather patterns around the globe.

In previous El Nino years, he said, the green turtle population bounced back in record numbers in subsequent years.

“The sky is not falling in!” added veteran sea turtle researcher George Balazs, who also works for NOAA. “Extreme fluctuations in numbers of nesting turtles annually are well known worldwide everywhere the green turtle occurs. That’s how they conduct their lifestyle, and it’s worked very well for a long time — back to the age of dinosaurs.”

The International Union for Conservation of Nature’s Red List identifies the Hawaiian subspecies of the green sea turtle as a species of least concern, saying an analysis of the science indicates that the population is “approaching full recovery to pre-exploitation levels, continues to grow, and anthropogenic (man-made) hazards do not appear to be restricting population recovery.”

The Hawaiian green turtle remains “threatened” under the the Endangered Species Act despite a petition last year that sought to remove the animal from the list.

A 2015 study by Balazs found that the Hawaiian green turtle population numbers roughly 4,000 breeding females, “having rebounded from its near extinction in the early 1970s.”

The Papahanaumokuakea Marine National Monument was thrust into the spotlight after President Barack Obama increased its size fourfold just before the 10-day World Conservation Congress, which concluded Saturday in Honolulu.

The remote monument is now the largest protected conservation area in the United States.

The coral reefs and atolls of Papahanaumokuakea are home to more than 7,000 marine species, one quarter of which are endemic to the northwest islands, including the green turtle, Hawaiian monk seal, 14 million seabirds and four endemic land birds, including the world’s most endangered duck.

Scientists continue to discover new underwater species there, including a new deep-reef butterfly fish announced Tuesday.