Warmer seas are driving an unprecedented surge in octopus populations along the UK’s southwest coast, with 2025 being dubbed “the Year of the Blooming Octopus” by wildlife observers. The Wildlife Trusts’ latest marine review confirms that octopus numbers are at their highest since 1950, a change directly linked to warming winter temperatures caused by climate change.
Dramatic Population Increase
Fishermen have reported a record catch of over 1,200 tonnes of octopus in UK waters this summer – a staggering increase compared to previous years. The most common species observed is Octopus vulgaris, typically found in warmer Mediterranean waters, suggesting a northward shift in its range. Volunteer sightings in Cornwall and Devon show a more than 1,500% rise in octopus encounters compared to 2023.
Matt Slater of the Cornwall Wildlife Trust describes the behavior as “exceptional”, noting octopuses are actively jet-propelling, camouflaging, and even walking on two legs underwater.
Implications for Fisheries and Ecosystems
The rapid population growth raises concerns about the impact on existing marine ecosystems. Octopuses are voracious predators of shellfish like lobster, crabs, and scallops, potentially disrupting fishing industries and altering consumer habits. Ruth Williams, head of marine for The Wildlife Trusts, emphasizes that adjustments will be necessary. “They are having an impact on those species around our shores. And as a consequence, they will be having an impact on our fishing industry.”
Government data shows crab landings declining while lobster, crawfish, and scallop catches remain stable. The situation highlights the need for fisheries to adapt to changing conditions – a process some are already beginning to explore.
Wider Environmental Trends
The octopus boom occurs against a backdrop of broader environmental challenges. The Wildlife Trusts’ review details a year marked by pollution incidents: a North Sea oil tanker collision releasing plastic resin pellets and a water treatment plant spill of bio-beads.
However, there are positive developments. Skomer Island, Pembrokeshire, recorded a record 46,000 puffins, and the Isle of Muck saw black and white bird numbers rebound thanks to rat removal efforts.
The surge in octopus populations serves as a stark reminder of how climate change is reshaping marine ecosystems. It remains unclear whether this bloom is a short-term phenomenon or a lasting trend, but it underscores the urgent need for adaptive fisheries management and continued monitoring of shifting species distributions.
