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

Exceptionally high sightings of one of the world's most intelligent invertebrates during the summer season have led to the declaration of 2025 as the year for octopuses in a seasonal assessment of Britain’s seas.

A Perfect Storm Driving a Surge

A mild winter followed by a remarkably hot spring triggered a huge population of *Octopus vulgaris* to establish themselves along the southern coastline of England, from Penzance in Cornwall to south Devon.

“The scale of the catch was roughly over a dozen times what we would typically see in Cornish waters,” commented a marine conservation officer. “Based on the totals, approximately 233,000 octopuses were found in these waters this year – representing a massive jump from the norm.”

*Octopus vulgaris* is native to these waters but usually so scarce it is seldom observed. A population bloom is caused by the dual effect of a mild winter and favorable spring temperatures. These ideal conditions meant a higher survival rate for young, possibly in part fuelled by significant populations of spider crabs also recorded.

A Rare Phenomenon

Previously, a population surge of this scale of this size was observed in the 1950s, with archival data indicating the one before that was in 1900.

The huge numbers of octopuses meant they could be readily observed in nearshore environments for a rare occurrence. Underwater recordings show octopuses gathering in groups – they are usually solitary – and “walking” along the bottom on their tentacle tips. One creature was even seen investigating a diver's camera.

“During a first dive there this year I saw multiple octopuses,” the specialist continued. “They are sizeable. There are two types in the region. One species is smaller, the size of a ball, but these newcomers can be up to a metre and a half wide.”

Looking Ahead & Coastal Highlights

Another mild winter going into 2026 could lead to a second bloom the following year, because in the past, in similar situations, events have occurred consecutively for two years running.

“But, it's improbable, from previous blooms, that it will become a permanent fixture,” they cautioned. “Marine life is unpredictable these days so it’s quite an unpredictable situation.”

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

• Highest-ever counts of gray seals observed in one northern region.
• Exceptional populations of puffins on an island off Wales.
• The initial discovery of the *Capellinia fustifera* nudibranch in a northern county, typically a southwestern species.
• A type of blenny discovered off the coast of a southern county for the first time.

Environmental Concerns

Challenges were also present, however. “The year was bookended by marine incidents,” stated an expert. “A major tanker collision in the North Sea and the release of tonnes of plastic biobeads off the southern coast highlighted ongoing threats. Conservation teams are working tirelessly to protect and restore our marine habitats.”