Timmy the whale died just days after release in North Sea

The humpback whale known as "Timmy" that washed up on a Danish beach likely died just days after it was hauled to the North Sea in a rescue attempt, German authorities said on Friday. 

Till Backhaus, the environment minister for the north-eastern German state of Mecklenburg-Vorpommern, said the animal is believed to have died on May 6 or 7, based off an analysis of data from a tracking sensor that was attached to the whale before it was released on May 2. 

The fate of Timmy the whale - who was later revealed to be a female - gripped Germany for months earlier this year after the mammal repeatedly stranded itself on the country's Baltic Sea coastline. 

After authorities failed to free the animal, a private initiative funded by millionaires stepped in to transport it back to the North Sea despite warnings from environmentalists that the whale was already severely weakened and likely to suffer greatly in the process. 

Two weeks after Timmy was released around 70 kilometres from Skagen, a port on Denmark's northern coast, she washed up dead on the Danish island of Anholt. 

Tracking data revealed the humpback whale had travelled some 215 kilometres back towards the Baltic Sea, which is not its natural habitat, before it died.

Backhaus said that once there, it slowed down again and was no longer diving as deep as previously. 

He added that it was sad how things turned out for the animal. "It wasn’t able to make the most of the opportunity."

The whale’s badly decomposed carcass was examined following its stranding on the Danish island, initially without yielding any concrete findings as to its cause of death. 

Timmy's remains were to be recycled into biodiesel in Denmark, although some of its bones are set to end up at the Natural History Museum in Copenhagen.