orca-shutterstock-full-width

Image: Janelle Lugge/Shutterstock.com

More whales and dolphins than ever spotted in the UK

It has been a record year for cetacean sightings in the waters around Britain.

The Sea Watch Foundation conducts an annual two-week count of whales, dolphins and porpoises across the country. The data collected helps to develop a snapshot of the distribution of these animals.

This year, more of these species than ever have been spotted by the public, including orcas, minke whales, humpback whales, bottlenose dolphins, and harbour porpoises. Thirteen species and more than 500 sightings have been reported.

Strandings data from the Museum also shows that more whales and dolphins are washing up along the UK coastline, possibly suggesting more animals are paying the country a visit.

Dr Chiara Giulia Bertulli, organiser of this year's national event, reported that 527 sightings were submitted after the nine-day count. Species numbers are up 50% on last year. 

She says, 'Cetacean data collection is strongly weather dependant. Factors such as sea state, swell height and visibility to the horizon affect how easily animals can be detected during a watch. Heavy rain and wind can even cause watches to be cancelled altogether. For these reasons, every year, we rely heavily on good weather conditions.

'The weather forecast at the beginning of the event was very poor…however, once the weather stabilized and the temperature increased the number of sightings increased dramatically and it showed.'

Gigantic visitors

Harbour porpoises can be seen virtually anywhere in the UK, and several dolphin species are regular visitors to our waters. Occasionally, members of the public can also catch sight of something larger.

During this summer's count, at least 30 minke whale sightings were reported, mostly off the western coasts of Scotland. Humpback whales were also spotted off the Aberdeenshire and East Yorkshire coasts.

Humpbacks are rarely seen in Britain but their numbers have been rising in recent years, according to the Sea Watch Foundation. They have mostly been recorded in northern Scotland, although there were also unconfirmed sightings in Wales in 2016.

 

In 2013, a humpback was seen in Norfolk for the first time since records began in the eighteenth century.

Humpbacks have been visiting UK waters more and more since 2004, and there is evidence that some of them may be returning individuals. They pass each year as part of their migration between feeding grounds in the North Atlantic and breeding grounds in the Caribbean and Azores.

Experts think the rise in UK sightings could be linked to a general increase in their population sizes, which have been recovering globally since last century's commercial whaling bans.

A rise in strandings

Cetacean numbers are also monitored by the Museum, and researchers have noticed the number of strandings is rising.

Officers at the Cetacean Strandings Programme investigate reports of dead or stranded animals along the coastline - usually hundreds each year. Since the programme began in 1913, there have been more than 12,000 logged reports of whale, dolphin and porpoise strandings, ranging from blue whales to harbour porpoises.

risso-dolphin-stranded-two-column

The Risso's dolphin that was found on 12 May 2018. Image by Gorleston Coastguard.

 

Research assistant Kate Swindells says, 'We continually receive more reports year on year, which is excellent and shows a real increase in public engagement and citizen science, particularly for ocean conservation.

'Whether or not there is an increase in sightings due to more people reporting, or actually an increase in cetaceans in UK waters remains unclear.'

Recent notable animals that have died on UK beaches include a sperm whale that washed up in Skegness, Lincolnshire in 2016, and a fin whale that stranded in Kent in October 2015.

Various species of dolphin and porpoises also wash up regularly.  A Risso's dolphin appeared in Norfolk in May, much further south than the usual range for this species.

In Scotland, the Scottish Marine Animal Strandings Scheme recently reported a stranded juvenile harp seal, a usually Arctic species that has rarely been spotted this far south. This raised concerns that this ice-dependent species may be changing their behaviour because of climate change and melting sea ice.

If you spot a stranded cetacean on the beach, contact the Stranding Programme.

Kate says, 'Even though it is extremely sad to see cetaceans dead, it can help us monitor distribution, abundance and threats to their populations, just like live sightings.'

A harbour porpoise just underneath the surface of green-coloured water.

Harbour porpoises are often seen all over the UK © By Erik Christensen (CC BY-SA 3.0), via Wikimedia Commons

Why are more cetaceans being seen?

It is possible that high temperatures and warmer waters attracted have species that normally stay away, like striped dolphins, and created the conditions for plankton fronts to develop. These would have encouraged fish, whales and dolphins to gather.

Chiara says, 'We are seeing a general longer term trend for warm water species to be extending their range further north - species like the short-beaked common dolphin, the Risso's dolphin and the striped dolphin. Since a greater number of species live in warm waters, the effects of climate change can actually be positive at mid latitudes such as around the British Isles.'

It's not good news for every species though. If waters warm, there is a risk we could lose other animals from our fauna, such as the Atlantic white-sided dolphin and white-beaked dolphin.

As well as that, if species that are used to tropical temperatures start making regular visits to the UK, they face a much wider range of human pressures along the industrialised coastlines of northern Europe.

Cetaceans Strandings Investigation Programme

Dive deeper

Find out more about life in the ocean, and explore the Museum's pioneering marine science.