DEVON — A recent study indicates an increase in octopus numbers off England's south-west coast, with populations expanding into Scotland and Wales. The octopus catch saw a 7,700% increase in 2025, according to a researcher, and Brixham market in Devon recorded sales of 100 tonnes of octopus in one day.
Observations from recreational divers and snorkellers, scientific surveys, and underwater monitoring form the basis of the study. This research found octopuses have spread along the north coasts of Devon and Cornwall. Octopus sightings have also been noted in Wales, Dorset, East Sussex, and Scotland. The common or Mediterranean octopus, Octopus vulgaris, is native to UK waters but typically exists in small numbers and is rarely observed.
Researchers say the increasing octopus numbers in UK waters are likely linked to warming seas and broader changes in the marine environment. Bryce Stewart, a senior researcher at the Marine Biological Association, said: "It is pretty extraordinary. We have had blooms before but everything I am seeing is telling me this is the biggest bloom we have seen, it is quite different." A sudden increase in the octopus population, known as a bloom, is caused by a combination of a mild winter followed by a warm spring breeding season. Stewart added: "Now we have warmer waters much more suited to these animals, we are seeing a huge increase in numbers."
Hundreds of divers and snorkellers assisted scientists in surveying the octopus population. Octopuses are known to target crabs and lobsters found in fishers' pots, and they also prey on shellfish and some other fish in the region. Stewart stated: "Some fishermen have had to sell their boats because of the impact on crab and lobster populations, while others are doing extremely well."
Octopuses serve as a food source for seals, conga eels, and rare Risso's dolphins. Stewart also noted: "It is a shake-up of the whole ecosystem."