A minke whale has beached and died at Portstewart Strand in County Londonderry.
The Department of Agriculture, Environment and Rural Affairs (DAERA) said it happened on Sunday evening.
A spokesperson from the department said officials had been in touch with the National Trust and that assessments would be made on Monday.
The National Trust has asked the public to keep a distance from the carcass while it works with other agencies and experts “to determine next steps”.
“Until this process is safely complete, we urge the public to continue to follow all signage and keep a safe distance,” a spokeswoman said.
Dog walkers are being asked to keep their pets on a lead and under control if walking on the strand.
The National Trust spokeswoman added: “Decaying marine mammals pose a serious health risk. They can carry a range of diseases that are transmissible to humans and dogs.”
While minke whales are known to be among the smallest, they can grow to about 35 feet (10m) and weigh up to 20,000 pounds (9,000 kg).
The species can usually be seen between July and October in UK waters and live for up to 50 years.
Whales can come ashore for many reasons, including injury, illness, bad weather and navigational errors leading them into shallow water.
