The two dolphins, both adult males, were found stranded on the Onsala peninsula south of Sweden’s second city Gothenburg.
“Normally, you’d find [this species] in tropical and temperate waters, so it’s unclear how they ended up here in February. Perhaps they were following a shoal of fish and lost their way,” Anders Nilsson, biologist at the Gothenburg Museum of Natural History, tells news agency TT.
Speaking to Swedish Radio News, Nilsson says that neither dolphin had scars from propellers or fishing nets.
“They both looked as though they were in good shape. It’s a bit of a mystery,” he says.
The dolphins’ bodies have been taken to the Gothenburg Museum of Natural History, and will subsequently be sent to the natural history museum in Stockholm for examination.