Why are sperm whales getting stranded in the UK?

In the past fortnight 29 sperm whales have washed up on the shores of the UK and Europe.

The North Sea is too shallow for whales which need at least 400 metres of water to dive. But why are the mammals entering the shallow waters?

Sally Hamilton, Head of ORCA, tells ITV News what may have happened.

  • Why are whales in the North Sea?

The most likely explanation is that they are following a food source - their favourite of which is deep water squid and octopus.

Whales' favourite food is octopus and squid. Credit: PA

Once they get into the North Sea, the water averages around 300 metres deep and moving south it becomes narrower and even shallower and they end up getting stuck.

  • Why can't the whales navigate their way out of shallow waters?

Whales start to lose their bearings in shallow water because they can't echolocate - communicate through sonar - effectively.

The mud flats and sloping banks cause the whales' navigational cues to become disorientated.

Sonar from ships and submarines is also known to have an effect on dolphins and whales but it is unclear if this was an issue in this case.

Windfarms could be causing vibrations which affect whales. Credit: PA
  • Could vibrations from offshore windfarms also be a factor?

It has been suggested that offshore wind farms causing vibrations in the water may also be confusing the whales.

Ms Hamilton said that it "is an established fact" that seismic activity and naval sonar does impact whales and dolphins.

"Whether or not that is what happened in this case, it is still is a theory, and needs to be examined," she said.

  • Could global warming be a factor?

Ms Hamilton said that there has been discussion about currents and warmer temperatures of the seas.

"That will certainly impact the availability of prey," she said. "So if the seas are getting warmer around our coast line, that will then affect the productivity of the prey and whales will follow their food."

A team of experts carry out a post-mortem on the whale which beached in Norfolk. Credit: PA
  • Can we expect any more strandings?

It depends how big the pod was and if they all followed each other into the North Sea.

At the moment, 29 have stranded. If the bachelor pod was bigger than that, there may be more strandings to come.

The whale at Hunstanton before it died. Credit: UK Coastguard
  • Can stranded whales be saved?

One sperm whale died on Thursday night after becoming stranded in Hunstanton beach in Norfolk.

Another five have died in the past fortnight after washing up along the Norfolk and Lincolnshire coasts.

Once beached, Ms Hamilton explained it was very hard to save the whales as it is the stranding itself which kills them.