‘Partying’ dolphins and rare sea slug resembling glowing lump of coal found in UK waters

Highlights of Wildlife Trusts’ 2020 marine review include shoal of Atlantic bluefin tuna up to 10ft long and swimming at speeds of over 40 mph spotted chasing mackerel, sardines and herring from Cornwall to Kent, writes Tom Batchelor

Bottlenose dolphins spotted off the coast of Redcar (Simon Wilcock)

An extremely rare sea slug, sand lizards and 30 bottlenose dolphins seen “partying” off the Teesside coast are among the creatures to feature in an annual review of marine life spotted in UK waters in the past 12 months.

Thousands of Atlantic bluefin tuna were witnessed in a rare “run” up the English Channel from Cornwall to Kent and a baby Risso’s dolphin was filmed being born in Wales.

The Wildlife Trusts’ 2020 marine review also reported an “explosion” in Arctic terns – up by 2,900 per cent – as well as increasing numbers of grey seals.

However the charity warned that marine wildlife was in “greater peril than ever” from plastic, litter, discarded fishing gear and disposable personal protective equipment.

Sir David Attenborough, president emeritus of the Wildlife Trusts, said: “The seas around the UK are home to the most extraordinary wildlife.

“We’re fortunate that our seas are protected by a blue belt of marine protected areas but sadly this does not prevent damaging activities still occurring in these special places.

“Bottom-towed dredging and trawling destroys fragile sea fans and soft corals on the seabed, while dredging to install cables to offshore wind farms changes the seabed and its wildlife forever.

“For too long we have taken from the sea with little regard for the consequences. We are all aware of the problems presented by plastic litter, but some pollutants and impacts are hidden from view, beneath the surface of the waves. Our government needs to tackle these problems but we can all do our bit too.”

Among the highlights of the review was a shoal of Atlantic bluefin tuna measuring up to 10ft long and swimming at speeds of over 40 mph, which were spotted chasing mackerel, sardines and herring from Cornwall and Devon in the west as far east as Folkestone in Kent.

At some points, the bluefin tuna were accompanied by porpoise, minke whale and dolphins, in a huge feeding frenzy.

Abby Crosby, marine conservation officer, Cornwall Wildlife Trust said: “No one who saw this intense display of the power, aggression and athletic prowess of bluefin tuna says they will ever forget it.”

A rare miniscule orange and black sap sucking sea slug called Placida cremoniana measuring just millimetres in length was also observed in Cornwall.

The species resembles a glowing lump of coal – but one covered in spikes – and is more usually found in the Pacific or Mediterranean.

Two orcas – killer whales – were seen in Strangford Lough for the first time in at least 50 years in May, while the Cumbria Wildlife Trust reported 412 grey seals and five pups at South Walney nature reserve.

The recorded population has increased dramatically, from only a couple of seals seen using the nature reserve in the 1980s.

In early August, more than 30 bottlenose dolphins were observed on just one day frolicking off Saltburn Pier.

The dolphin group was also spotted off Redcar and Hartlepool, again visible from the coastline.

Jacky Watson, wilder coast officer at Tees Valley Wildlife Trust, said: “The sight of dolphins off Teesside was a complete revelation for lots of local people and a gift for photographers. 

"Many people had no idea bottlenose dolphins could be seen in UK waters, let alone here. 

“This partying pod of dolphins were highly visible, playing, breaching vertically, racing along at top speed with fin after fin arcing through the waves.”

Lancashire Wildlife Trust also revealed a new sand lizard population in August – the most northerly population of rare sand lizards in England – which the charity said was thriving for the first time since the 1960s.

Jessica Newman, was involved in the Fylde Sand Dunes Project, said: “England can now boast sand lizard populations from our southern counties all the way up to Fylde Sand Dunes in Lancashire. It may still be our rarest lizard, but this bright green jewel of a creature deserves to be back home in the north.”

In December 2020, new Marine Protected Areas were announced in Scotland, for species including basking sharks and minke whales, alongside 12 new Special Protection Areas for marine birds.

Joan Edwards, director of living seas at the Wildlife Trusts, said: “In 2020 people flocked to the sea as soon as lockdown restrictions were lifted – they needed the coast as never before.

“Wildlife Trusts around the country were reporting a surge of public interest in marine life and coastal species. From the Risso’s dolphins in Wales and minke whales off Yorkshire, to the partying bottlenose dolphins off Teeside and the bluefin tuna racing up the south coast – people delighted in seeing marine life and it lifted the hearts of millions in this difficult year.

“However, we have taken these wonders for granted for too long and it’s vital we recognise that the future of life on earth is inseparable from the health of the sea.

“Our oceans are in trouble and the UK will not achieve its climate and environmental targets without restoring marine habitats. That’s why The Wildlife Trusts are appealing for £30m to help put 30 per cent of land and sea into recovery for nature by 2030.”

Ruth Williams, a marine conservation manager with the Cornwall Wildlife Trust, added: “Disposable PPE gloves and face masks were everywhere this summer and our beach cleans find it every time.

“Littered PPE not only looks unsightly. If left lying around it poses a risk as it could injure wildlife too.”