Octopus Surge Threatens UK Fishermen

Unprecedented Octopus Bloom Threatens UK Shellfish Industry

Veteran fisherman Brian Tapper recently faced a series of unexpected challenges while checking his 1,200 crab pots in the waters off southwest England. During this year’s crabbing season, he encountered an unusual pattern: initially, the pots were nearly empty, then filled with octopuses starting in May, and finally returning to near emptiness over the past month.

This phenomenon has been observed along the UK's Devon and southern Cornwall coastlines, where rising sea temperatures have triggered what is being called the largest octopus bloom in British waters in 75 years. The situation has had a significant impact on the shellfish industry, as these tentacled mollusks are known for their voracious appetite, often consuming crustaceans like crabs and other shellfish.

Tapper’s wife has already closed her dockside crab processing factory due to the reduced catch, and Tapper himself is uncertain about the future of his business. “It's like a perfect storm for us,” he said from Plymouth Harbour, where his three purpose-built crab fishing vessels remain idle. He estimates that his catch has dropped by half and could fall by as much as four-fifths in 2025.

An 18-month marine heatwave in the region is believed to be the primary cause of the octopus bloom. Climate scientists attribute global warming, driven by human activities such as burning fossil fuels, to the rising ocean temperatures. Tapper, who has fished for 39 years, described the situation as unprecedented. “I've never seen octopus like this. I've never seen an instant change like this. It's so quick. They're a plague.”

Rising Octopus Landings and Falling Shellfish Catch

According to data from the Marine Management Organisation, a government agency, UK fishermen landed more than 1,200 tonnes of octopus in the first six months of this year. This compares to less than 150 tonnes in the same period in 2023 and less than 80 tonnes in those months last year. Meanwhile, landings of shellfish, such as brown crab, have significantly declined in 2025.

Sue MacKenzie, owner of Passionate About Fish, expressed concern over the impact of the octopus bloom on local species. “They’re eating our indigenous species at a rate that nobody can anticipate — it’s quite scary,” she said.

While decent market prices for octopus helped offset some losses, this advantage was short-lived. By July, the numbers of octopus began to drop considerably. Beshlie Pool, executive officer at the South Devon and Channel Shellfishermen cooperative association, noted that some members have struggled to catch even a single octopus this season.

Chris Kelly, a fisherman who uses pots, nets, and lines from his seven-metre vessel "Shadow," has benefited from the high demand for octopus. However, he worries about the long-term impact on other species. “But then we're catching no lobsters, and long-term, you're thinking 'what's it going to do to the stocks?'” he said.

Adapting to the New Reality

The shift in seafood availability has also affected restaurants and food retailers. Caroline Bennett, owner of Sole of Discretion, said her company has had to source octopus from further down the coast due to the lack of crab. “This is the first year we've bought it. We didn't have any crab at all to sell,” she explained.

Local and national officials have responded by commissioning an urgent study into the situation, with an initial report expected in October. Bryce Stewart, a marine scientist at the University of Plymouth leading the research, pointed out that past octopus blooms in Britain, such as those in 1950, the 1930s, and 1899, were all linked to warmer-than-usual waters.

However, Stewart suspects that octopuses are now breeding in local waters, which could explain their sudden increase and subsequent decline. Both male and female Atlantic longarm octopus typically live for about 18 months and die shortly after breeding. “They eat everything, they're ferocious, and they start to breed. It's like the ultimate live fast, die young life cycle,” he said.

Despite the uncertainty, Tapper remains pessimistic about the future. “The crab won't come back in my working lifetime,” he predicted. “The reproduction of a crab would probably take five to 10 years to get to its marketable size, and I haven't got five to 10 years (to) pay the bills.”