A dead porpoise, suspected to have been carrying a stillborn calf, was discovered in Hong Kong waters on Tuesday.

The Agriculture, Fisheries and Conservation Department said it had retrieved the carcass, which was identified as a finless porpoise, in the waters near Ap Chau, one of the city’s outlying islands, on Tuesday evening.

It added that a necropsy would be conducted by veterinarians, with the Ocean Park Conservation Foundation to also investigate. The park confirmed it would assist with the case.

The mammal was spotted by boat captain Vincent Tong Chi-kin near Ap Chau in the morning. His vessel was conducting coastal clean-up work for the Food and Environmental Hygiene Department.

“We spotted a grey-black object when steering from Lai Chi Wo to Ap Chau. It turned out to be the body of a mammal when we got close,” he said.

He added that the six-foot (1.8 metres) carcass was intact, with no visible scratches.