Humpback Stranded

A young humpback whale is thought to have been the first of the creatures to strand in London’s River Thames.

The 9.5m-long juvenile was first spotted by volunteers from British Divers Marine Life Rescue (BDMLR), floating dead off Gravesend. Three days later it came ashore near Dartford Bridge, and was removed by Port of London Authority (PLA).

A post mortem revealed that the whale, a male estimated at about two years old, had died of starvation. This indicated that it had entered the river, where there would have been little or no suitable food, before it had died.

Rob Deaville, a zoologist at the Zoological Society of London, hoped that more tests would “provide additional information about what happened to this whale”. They also represented a “rare opportunity to examine a truly extraordinary animal at close quarters”.

When whales get into the river system it is, said Deaville, “very difficult” for them to retrace their route back out to sea. They become confused by the river’s topography and assorted noise from boats and other activity.

Initial entry into the river can be caused by navigational error, possibly compounded again by noise confusion once near busy shipping lanes; or sickness.

An increase in such incidents over time might mean that general migration routes are being altered, perhaps by changing sea conditions caused by climate change.

Only 12 humpbacks have stranded, alive or dead, around the UK over the past 20 years. Before the Thames stranding, the last was at Port Talbot in Wales, in 2007.