2025 Proclaimed 'The Octopus Year' Off England's Southern Shores.
Unprecedented observations of one of the world's most intelligent invertebrates this past summer have resulted in the designation of 2025 as “the year of the octopus” in an annual review of Britain’s seas.
Ideal Conditions Leading to an Explosion
A gentle winter coupled with a very warm springtime catalyzed unprecedented numbers of Mediterranean octopuses to establish themselves along the shores from Cornwall to Devon, across the southwestern peninsula.
“The reported landings was approximately over a dozen times what we would usually anticipate in the waters around Cornwall,” commented an ocean conservation expert. “Calculating the figures, approximately 233,000 octopuses were present in British seas this year – that’s a huge increase from what is typical.”
*Octopus vulgaris* is native to these waters but usually so scarce it is infrequently encountered. A population bloom is caused by the dual effect of gentle winter conditions and favorable spring temperatures. These ideal conditions meant increased juvenile survival, possibly in part fuelled by significant populations of spider crabs seen in the area.
A Rare Phenomenon
The most recent occasion, a population surge of this scale comparable was observed in the 1950s, with archival data indicating the one before that was in the turn of the 20th century.
The sheer quantity of octopuses meant they could be readily observed in nearshore environments for a rare occurrence. Underwater recordings show octopuses gathering in groups – unlike their typical solitary behavior – and “walking” along the seabed on their tentacle tips. One individual was even recorded reaching for submarine recording equipment.
“On my initial dive there this year I saw multiple octopuses,” they noted. “They are large specimens. Two kinds exist in UK waters. One species is rather small, about the size of a football, but these common octopuses can be reaching impressive sizes.”
Looking Ahead & Coastal Highlights
Another mild winter heading into next year could lead to another surge in 2026, because in the past, with such patterns, populations have surged again for two years running.
“However, it is unlikely, looking at history, that it will persist indefinitely,” they said. “But the sea keeps giving us surprises at the moment so it’s a very uncertain scenario.”
The annual review also celebrated further encouraging coastal sightings across British shores, including:
- Highest-ever counts of grey seals seen in Cumbria.
- Peak numbers of the iconic seabirds on a Welsh island.
- The first recording of a rare sea slug in Yorkshire, typically a southwestern species.
- A type of blenny discovered off the coast of Sussex for the inaugural time.
Environmental Concerns
Not everything was good news, however. “The period was framed by ecological challenges,” said a head of marine conservation. “A major tanker collision in the North Sea and an accidental discharge of industrial pellets off the southern coast served as stark reminders. Staff and volunteers are putting in immense work to defend and heal our coasts.”