The Wildlife Trusts’ annual round-up of life in UK seas presents tales of hope and heartache through spectacular encounters, conservation successes and challenges for marine and coastal wildlife. The highs and lows for 2023 include:

• Bait ball feeding frenzies dominated by Atlantic bluefin tuna, humpback and fin whales
• First ever Highly Protected Marine Areas designated in the UK
• Danger from human disturbance, pollution and avian flu

Wildlife enthusiasts were treated to a bumper year for Risso’s dolphins in the South West, including in the Wembury Voluntary Marine Conservation Area. There were multiple reports of super-pod feeding frenzies off south-west England, with common dolphins and fin whales joining in.

A rise in sightings of Atlantic bluefin tuna, fin whales and humpback whales could be a sign that these species are recovering. There were multiple reports of bait ball feeding frenzies involving whales, dolphin, and tuna – from Scotland to Scilly. A bait ball is formed when a predator forces fish to group together into a dense ball – then gannets, cetaceans and tuna dive in to feed, creating a ‘boiling’ sea of activity.

Dr Lissa Batey, Head of Marine Conservation at The Wildlife Trusts, witnessed this phenomenon off the Devon coast. She says:

“I went on a family dolphin-watching trip and spotted large numbers of diving gannets. We sailed nearer and as we approached the water appeared to be ‘boiling’ with activity. An extraordinary number of dolphins appeared all around us feeding on a giant fish bait ball below. Bluefin tuna began to leap high out of the water in the middle of the turmoil. Suddenly fin whales appeared and blew high columns in the air before lunging beneath to gorge on the fish. It was an incredibly exciting spectacle and one that I’ve heard other people have enjoyed off the UK coast this summer.”

Atlantic bluefin tuna, which grow to over 10ft and weigh more than 1,000lbs, were once common in UK waters. Overfishing caused numbers to plummet during the 20th century. Sightings became rare and the fish had all but vanished by the 1990s. A 15-year recovery plan launched in 2007 saw numbers improve and eventually, bluefin tuna was removed from IUCN’s Red List of Endangered Species. Witnesses recorded many sightings in 2023 from Devon, Cornwall, Isles of Scilly, Scotland, Alderney to Dorset where the local Wildlife Trust recorded a 9ft-long bluefin tuna washed up at Kimmeridge Bay.

Pete Burgess, Devon Wildlife Trust's Director of Nature Recovery, says:

"Regulation is vital for protecting the natural world and reversing wildlife declines. The end of commercial whaling has brought humpbacks and fin whales back to UK waters, and we’re now seeing bluefin tuna return to our coasts after being decimated by industrial scale fishing practices. This stunning fish has returned from the brink of extinction and there is a genuine risk it may suffer the same fate again.

Bluefins can reach 250kg in weight – similar in size to our largest dolphins. Now is the time to celebrate their return and provide more opportunities for people to see the amazing scenes of bluefins from our coastlines. We also need to understand more about this species and how we can ensure their populations thrive – not to mark their return by opening-up new fisheries. When we give nature space, wildlife can recover – it’s as simple as that. We must act faster to protect the UK target of 30% of seas by 2030."

Other exciting wildlife encounters this year include:

• Flying fish in Plymouth Sound – while an Atlantic species, these are rarely seen in UK coastal waters.
• Very unusually, a pod of 60 porpoises was seen hunting in a line in Bigbury Bay, off the south coast of Devon, in July.
• Osprey have become regular passage visitors to Devon on their migration to and from Africa. This spectacular bird was spotted flying above DWT's Meeth Quarry nature reserve this summer. Having been driven to extinction through persecution in the Victorian era, they have made a remarkable comeback thanks to conservation efforts!
• DWT's Wembury Marine Centre has had a fantastic year engaging people with life below the waves, spotting a range of marine life including lobsters, sea hares, St Piran’s hermit crabs and wrasse. Night-time rockpools using UV touches revealed spider crabs and luminous anemones, while further down the coast, multiple sightings of large octopus were also reported by scuba divers in Plymouth. However, invasive species have also been spotted, including Devil’s tongue weed, leathery sea squirts, slipper limpets and Pacific oysters.

Sea champions

UK marine conservation would not be possible without the support of fantastic staff and volunteers.

• John has been a dedicated volunteer at DWT’s Wembury Marine Centre for 20 years, and so DWT has given him a 20 years of service award. John does many different things at Wembury, and we are very grateful to him for his 20 years and hope for many more!
• 60 volunteers are now trained and ready to record key information about marine strandings on Devon's coasts.
• Devon's Shoresearch network had an amazing year of surveys, with 163 people recording around 200 species, and a total of 962 records!

Wembury Marine Centre’s summer season closed with a massive beach clean in September. 49 volunteers joined Devon Wildlife Trust staff to remove litter and other objects from 500m of the popular beach and rocky shoreline. 599 foreign objects weighing nearly 24kg were found and bagged. Unsurprisingly plastic pollution topped the finds list accounting for 85% of the pollution. Plastic bags, bottles, fishing line/nets and dog poo bags all featured heavily.

The worldwide pandemic of avian flu continued to devastate UK seabirds. While there are signs that some birds are showing immunity, vast numbers have been lost. A seabird survey by the Isles of Scilly Wildlife Trust and RSPB painted a worrying picture for one of the most significant seabird colonies in England. Findings include:

• Overall declines of 20% of seabirds since the last survey in 2015
• A loss of almost half of the islands’ seabirds in the last 30 years
• Common terns lost as an annual breeder, with kittiwakes likely to follow
• Steep declines of the greater black-backed gull, 38%, and lesser black-backed gull, 58%, and the red-listed herring gull, 40%

Read more about avian flu and what The Wildlife Trusts are calling for.

New legal protection and marine conservation projects offer hope for the sea

2023 was a historic year for marine conservation as the first ever Highly Protected Marine Areas (HPMAs) were designated in English waters. Three places were chosen: Allonby Bay, Cumbria, Dolphin Head, Sussex and North-East of Farnes Deep in the North Sea, are now protected from all damaging activities. The Wildlife Trusts welcome the designations but warn that these only cover 0.4% of English seas – and many more HPMAs are needed to protect marine wildlife and tackle climate change.

Dr Lissa Batey, head of marine conservation at The Wildlife Trusts, says:

“2023 has been a historic year for marine conservation with the creation of the first Highly Protected Marine Areas in English waters. This is a huge milestone which was achieved thanks to years of campaigning by our sea-loving supporters. This new gold-standard of protection will stop all damaging activities such as trawling and enables marine wildlife to recover, benefiting fishers and carbon storing habitats. These special places cover less than half a percent of English seas – so it’s a tiny first step towards more designations."