Record-breaking observations of one of the world's most intelligent invertebrates over the summer months have prompted the declaration of 2025 as “the year of the octopus” in an annual review of UK coastal waters.
Ideal Conditions Driving a Surge
An unusually warm winter and then an exceptionally warm spring prompted a huge population of Mediterranean octopuses 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 normally expect in the waters around Cornwall,” explained a marine conservation officer. “When we added up the numbers, approximately 233,000 octopuses were caught in UK waters this year – representing a massive jump from historical averages.”
*Octopus vulgaris* is native to these waters but typically so rare it is infrequently encountered. An explosive growth is attributed to a combination of gentle winter conditions and favorable spring temperatures. Such favorable circumstances meant increased juvenile survival, potentially supported by large numbers of spider crabs noted in recent years.
A Historic Event
The last time, an octopus bloom of this size was recorded in 1950, with past documentation indicating the previous major event occurred in the turn of the 20th century.
The remarkable abundance of octopuses meant they could be readily observed in coastal areas for the first time in living memory. Underwater recordings show octopuses being sociable – unlike their typical solitary behavior – and moving along the ocean floor on the tips of their limbs. One creature was even filmed grabbing an underwater camera.
“On my initial dive off the Lizard peninsula this year I saw five octopuses,” they noted. “They are sizeable. There are two types in these waters. One species is smaller, about the size of a football, but these common octopuses can be reaching impressive sizes.”
Predictions and Marine Joy
A second gentle winter going into 2026 could lead to another surge next year, because in the past, with such patterns, populations have surged again for two years in a row.
“Still, the chances are low, from previous blooms, that it will go on for a long time,” they cautioned. “But the sea keeps giving us surprises these days so it’s quite an unpredictable situation.”
The annual review also highlighted additional positive marine news across British shores, including:
- A record number of gray seals recorded in Cumbria.
- Peak numbers of puffins on a Welsh island.
- The initial discovery of an unusual mollusc in a northern county, normally residing farther south.
- A type of blenny spotted off the coast of a southern county for the first time.
Environmental Concerns
Not everything was good news, however. “The year was bookended by environmental disasters,” stated an expert. “A significant shipping incident in March and an accidental discharge of tonnes of plastic biobeads off the southern coast were serious issues. Dedicated individuals are putting in immense work to protect and restore our marine habitats.”
