2025 Declared 'The Octopus Year' Along Britain's South Coast.

Unprecedented observations of one of the world's most intelligent invertebrates during the summer season have led to the designation of 2025 as the octopus's year in an annual review of UK coastal waters.

A Confluence of Factors for a Population Boom

An unusually warm winter coupled with an exceptionally warm spring triggered a huge population of common octopuses (*Octopus vulgaris*) to establish themselves along England’s south coast, from Penzance in Cornwall to south Devon.

“The volume of octopuses caught was approximately 13 times what we would typically see in the waters around Cornwall,” commented an ocean conservation expert. “Based on the totals, approximately 233,000 octopuses were found in British seas this year – that’s a huge increase from historical averages.”

*Octopus vulgaris* is native to UK waters but typically so rare it is seldom observed. A population bloom is attributed to a combination of a mild winter and favorable spring temperatures. Such favorable circumstances meant a higher survival rate for young, possibly in part fuelled by large numbers of spider crabs seen in the area.

A Historic Event

The most recent occasion, an octopus bloom of this size was documented in the 1950s, with historical records indicating the one before that occurred in the turn of the 20th century.

The remarkable abundance of octopuses meant they could be readily observed in coastal areas for a rare occurrence. Video footage show octopuses being sociable – unlike their typical solitary behavior – and moving along the ocean floor on the tips of their limbs. One individual was even seen investigating an underwater camera.

“On my initial dive there this year I saw five octopuses,” the specialist continued. “They are large specimens. Two kinds exist in these waters. One species is rather small, football-sized, but the *Octopus vulgaris* can be up to a metre and a half wide.”

Future Prospects and Other Surprises

If conditions remain mild going into 2026 could lead to a second bloom next year, because in the past, under these conditions, populations have surged again for two years running.

“Still, the chances are low, looking at history, that it will become a permanent fixture,” they cautioned. “But the sea keeps giving us surprises at the moment so it’s quite an unpredictable situation.”

The annual review also highlighted other “surprises, successes and joyful moments” around the UK coastline, including:

• Highest-ever counts of gray seals seen in one northern region.
• Peak numbers of the iconic seabirds on Skomer.
• The first recording of the *Capellinia fustifera* nudibranch in Yorkshire, typically a southwestern species.
• A variable blenny discovered off the coast of a southern county for the first occasion.

A Note of Caution

Not everything was good news, however. “The period was framed by environmental disasters,” noted a conservation leader. “A significant shipping incident in the North Sea and an accidental discharge of plastic pollution off the southern coast were serious issues. Dedicated individuals are putting in immense work to safeguard and rehabilitate our marine habitats.”