HOUSTON, United States

A string of mysterious whale deaths along the US East Coast has prompted a group of mayors in the state of New Jersey to call for an "immediate moratorium" on offshore wind farms. 

The announcement from 12 mayors came Monday following reports that another humpback whale was found dead off the New Jersey and New York coastline.

The whale washed ashore in Lido Beach, New York, bringing the total to at least six dead whales, but possibly eight, in the region in the past two months, according to the mayors. That brings the total to 18 dead whales along the US East Coast in that time, according to a report from the USA Today newspaper.

The mayors want to stop the current offshore wind energy development until federal and state scientists can assure the public that ocean noise related to wind farms poses no threat to whales.

"While we are not opposed to clean energy, we are concerned about the impacts these projects may already be having on our environment," they wrote in a letter to Washington, D.C. officials.

A dead humpback was spotted Saturday off the coast of Long Beach Island. Officials said it was not clear if the Lido Beach whale could be the same.

"This is the sixth stranded humpback whale reported in New Jersey, and the 18th large whale stranding along the East Coast, since December 1," said Andrea Gomez, a spokesperson for the Greater Atlantic Regional Fisheries Office at the National Oceanic and Atmospheric Administration (NOAA), in an interview with USA Today's Asbury Park Press.

NOAA said ship strikes and fishing gear entanglements are among the most common causes of death in humpback whales. The agency said the unusually high number of whale deaths among humpbacks dates to 2016 before offshore wind energy exploration began in the Atlantic Ocean.

The environmental activist group Greenpeace said caution is the best way to approach the whale deaths.

“There is a lot at stake, and we need answers to ensure we are doing what’s best for people and the planet," Arlo Hemphill of Greenpeace USA said in a statement. "At this time, due to the lack of evidence suggesting harm from offshore wind development, Greenpeace’s position remains that the best way to protect whales is to create ocean sanctuaries, eliminate single-use plastics at the source, and stop our dependency on oil and gas."