2025 Proclaimed the 'Year of the Octopus' Off Britain's South Coast.

Exceptionally high sightings of a remarkably clever cephalopod this past summer 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 a remarkably hot spring prompted unprecedented numbers of Mediterranean octopuses to settle along the shores from Cornwall to Devon, spanning the Cornish and Devonian coasts.

“The volume of octopuses caught was roughly over a dozen times what we would usually anticipate in Cornish waters,” explained a marine life specialist. “When we added up the numbers, around 233 thousand octopuses were caught in UK waters this year – which is a significant rise from historical averages.”

The common octopus is found in UK waters but ordinarily in such small numbers it is rarely seen. A sudden increase is attributed to the dual effect of a mild winter and favorable spring temperatures. Such favorable circumstances meant more larvae, possibly in part fuelled by abundant stocks of other marine life noted in recent years.

A Rare Phenomenon

The most recent occasion, such an octopus proliferation this significant was documented in the mid-20th century, with historical records indicating the one before that happened in the turn of the 20th century.

The huge numbers of octopuses meant they could be easily spotted in nearshore environments for a rare occurrence. Underwater recordings show octopuses congregating together – they are usually solitary – and “walking” along the seabed on their tentacle tips. A curious octopus was even filmed grabbing submarine recording equipment.

“During a first dive there this year I saw five of these creatures,” they noted. “They are sizeable. There are two types in UK waters. One species is quite small, about the size of a football, but the *Octopus vulgaris* can be up to a metre and a half wide.”

Predictions and Marine Joy

A second gentle winter going into 2026 could lead to a second bloom in 2026, because in the past, in similar situations, populations have surged again for two years running.

“Still, the chances are low, from previous blooms, that it will become a permanent fixture,” they said. “Marine life is unpredictable at the moment so it’s hard to forecast.”

The assessment also highlighted additional positive marine news along the coast, including:

• Unprecedented numbers of grey seals recorded in Cumbria.
• Record numbers of puffins on Skomer.
• A first-ever sighting of the *Capellinia fustifera* nudibranch in a northern county, typically a southwestern species.
• A Mediterranean fish species spotted off the coast of a southern county for the inaugural time.

A Note of Caution

Not everything was good news, however. “The period was framed by marine incidents,” noted a conservation leader. “A major tanker collision in March and an accidental discharge of industrial pellets off the Sussex coast served as stark reminders. Dedicated individuals are putting in immense work to defend and heal our shorelines.”