Dozens of East Coast mayors representing cities in three Democratic-led states — New Jersey, Delaware and Maryland — are calling for an offshore wind development moratorium in light of recent marine wildlife deaths.

In an open letter to Congress sent Tuesday, 50 mayors from across the three states said offshore wind development should immediately cease until a thorough investigation is conducted. The mayors expressed concern that the increasing number of whale and dolphin deaths is negatively impacting the ocean ecosystem their communities rely upon.

"Our coastal economies rely on a healthy ocean ecosystem to function, and we are increasingly concerned about the environmental impacts offshore wind may already be affecting our communities," the mayors wrote to Congress.

"The current level of marine mammal mortality is unacceptable, and we need answers," the letter continued. "In the absence of scientific evidence explaining the increase in marine mortality, we believe the connection between offshore wind activity and marine mammal mortality must be investigated now."

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A deceased whale stranded on a New York beach

A dead whale is found on a New York beach on Feb. 17. (Fatih Aktas/Anadolu Agency via Getty Images)

According to the mayors, since December, at least 39 whales and 37 dolphins have been found stranded on East Coast beaches near where energy developers have been conducting offshore wind surveys. Over the past five days alone, a humpback whale and six dolphins have been beached near such acoustic surveys which some environmentalists argue disturb wildlife.

For months, local leaders, Republican lawmakers and environmental groups have called for a moratorium on offshore wind development and an investigation into wildlife deaths. Their concerns have butt heads with clean energy proponents and Biden administration officials pushing offshore wind.

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Days after taking office, President Biden issued an executive action ordering his administration to expand opportunities for the offshore wind industry as part of his aggressive climate agenda to curb greenhouse gas emissions and stop global warming. Months later, he outlined goals to deploy 30 gigawatts of offshore wind energy by 2030, the most ambitious goal of its kind worldwide.

President Joe Biden points to a wind turbine size comparison chart during a meeting about the Federal-State Offshore Wind Implementation Partnership on June 23, 2022.

President Joe Biden points to a wind turbine size comparison chart during a meeting about the Federal-State Offshore Wind Implementation Partnership on June 23, 2022. (Drew Angerer/Getty Images)

"Two years ago, President Biden issued a bold challenge to move America towards a clean energy future," Interior Secretary Deb Haaland said in April. "The Interior Department answered that call and is moving rapidly to create a robust and sustainable clean energy economy with good-paying union jobs."

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And federal officials have thrown cold water on claims that offshore wind is causing whale deaths.

During a press briefing in January, officials with the National Oceanic and Atmospheric Administration noted there has been an unusual mortality event in relation to whale deaths along the East Coast dating back years and that recent whale deaths couldn't be attributed to energy operators.