2025 is ‘year of the octopus’ as record numbers spotted off England’s south coast | Marine life
Record sightings of one of the world’s most intelligent invertebrates over the summer have led the Wildlife Trust to declare 2025 the “year of the octopus” in its annual survey of British seas.
A mild winter followed by an exceptionally warm spring caused unprecedented numbers of Mediterranean octopuses to establish themselves along the south coast of England, from Penzance in Cornwall to south Devon.
“The scale of capture [recorded by local fishers] Matt Slater, marine conservation officer from Cornwall Wildlife Trust, said: “When we added up the figures, around 233,000 octopuses were caught in UK waters this year, which is a huge increase from what you would normally expect.”
Common or Mediterranean octopus, octopus vulgarisIt is endemic to UK waters but is normally rarely seen in such small numbers. A sudden increase in population – the bloom – is caused by the combination of a warm winter followed by a warm breeding season in the spring. Slater said the ideal conditions meant that most larvae of the common octopus were likely to survive, perhaps driven in part by the large numbers of spider crabs recorded off the southern coast in recent years.
An octopus explosion of the magnitude observed in 2025 was last recorded in 1950. Records of the Marine Biological Society of the United Kingdom It shows that the last recorded bloom before this was in 1900.
The large numbers of octopuses off the south coast meant they could be easily seen in shallow waters for the first time in recent history. Video footage from divers shows octopuses congregating in groups (they are usually solitary) and “walking” on the tips of their limbs along the seabed. One was even filmed looking at an underwater camera.
“On my first dive off the Lizard peninsula this year, I saw five octopuses,” Slater said. “And they’re big. There are two species of octopus in UK waters. There’s the coiled octopus, which is quite small, only reaching the size of a football, but these common octopuses can get up to a meter and a half wide.”
Another mild winter heading into 2026 means a second bloom could be possible next year, Slater said, because historically blooms under those conditions have repeated themselves for two consecutive years.
“But judging by past events, this is unlikely to continue for long,” he said. “But the sea continues to give us surprises at the moment, so it’s quite an unpredictable situation.”
The Wildlife Trust noted that some of the other “surprises, successes and joyful moments” along the UK coastline included a record number of gray seals observed by the Cumbria Wildlife Trust, as well as a record number of puffins on Skomer, an island off the coast of Wales famous for its birds.
Other wildlife has been recorded in unusual places. A volunteer from Shoresearch, the Wildlife Trust’s national citizen science research programme, recorded the first capellinia fustifera The Yorkshire sea slug is a 12mm mollusc that resembles a gnarled root vegetable and is commonly found in the south-west. Also a variable blenny, a Mediterranean fish, It was first discovered off the coast of Sussex. Populations were previously limited to the West Country.
But it wasn’t all good news. “The year has been one of environmental disaster,” said Ruth Williams, head of marine conservation at the Wildlife Trusts. “[There was] tanker collision in the North Sea in March and the release of tonnes of biobeads off the Sussex coast in November. “Our Wildlife Trust staff and volunteers work hard to protect and restore our coastlines.”
