2025 Declared The Year for Octopuses Off Britain's Southern Shores.

Unprecedented encounters of one of the world's most intelligent invertebrates over the summer months have resulted in the naming of 2025 as the octopus's year in an annual review of Britain’s seas.

A Confluence of Factors for a Population Boom

A gentle winter coupled with a remarkably hot spring triggered a huge population of *Octopus vulgaris* to take up residence along the southern coastline of England, spanning the Cornish and Devonian coasts.

“The volume of octopuses caught was of the order of about over a dozen times what we would normally expect in the waters around Cornwall,” stated a marine life specialist. “Calculating the figures, around 233 thousand octopuses were caught in UK waters this year – that’s a huge increase from historical averages.”

The Mediterranean octopus is indigenous to these waters but typically so rare it is infrequently encountered. An explosive growth is caused by the dual effect of a mild winter and a warm breeding season. Such favorable circumstances meant increased juvenile survival, potentially supported by abundant stocks of spider crabs seen in the area.

A Rare Phenomenon

The last time, a population surge of this scale comparable was observed in 1950, with archival data indicating the one before that occurred in 1900.

The remarkable abundance of octopuses meant they could be easily spotted in nearshore environments for the first time in recent history. Video footage show octopuses gathering in groups – they are usually solitary – and ambulating along the bottom on their tentacle tips. One creature was even filmed grabbing submarine recording equipment.

“On my initial dive in that area this year I saw five octopuses,” the specialist continued. “And these are big. There are two types in the region. One species is quite small, the size of a ball, but the *Octopus vulgaris* can be up to a metre and a half wide.”

Looking Ahead & Coastal Highlights

If conditions remain mild going into 2026 could lead to another surge next year, because based on records, in similar situations, the blooms have repeated for two years running.

“However, it is unlikely, looking at history, that it will persist indefinitely,” they said. “The ocean is full of surprises at the moment so it’s quite an unpredictable situation.”

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

• Unprecedented numbers of grey seals recorded in one northern region.
• Exceptional populations of puffins on a Welsh island.
• The first recording of a rare sea slug in a northern county, usually found in the south-west.
• A type of blenny found off the coast of Sussex for the first time.

Environmental Concerns

Challenges were also present, however. “The year was bookended by marine incidents,” noted a conservation leader. “A major tanker collision in March and the release of industrial pellets off the Sussex coast served as stark reminders. Staff and volunteers are working tirelessly to protect and restore our coasts.”