Why are we seeing more octopuses along the South West coast?
There has been a noticeable rise in the number of octopuses in South West waters in recent months, but why is that and what threat does it pose to other marine animals?
The species of octopus that is being spotted in Devon is the Common Octopus. It is the species most likely to be seen by divers and snorkellers around the UK.
But while their name implies they are nothing out of the ordinary, marine experts have told us the more frequent sightings in the region could reveal interesting insight into the state of our natural world.
"The increased sightings could reflect the changing sea conditions in our region", marine officer at the Devon Wildlife Trust, Carli Cocciardi, said.
"South West England is near the northern edge of the Common Octopuses' typical range.
"Recent increases of the octopuses could be linked to climate change, better prey availability and ocean currents."
'The octopus plague'
Experts say octopus population booms in the West Country have happened periodically since the late 1800s.
Dr Keith Hiscock, Associate Fellow at the Marine Biological Association, said there was a "plague" of Common Octopuses in the late 1800s and early 1900s.
"In recent years, we have reported a greater persistence of the species from high numbers in 2022, but then fewer numbers in 2023.
He added: "Now, in 2025, the 'outburst' being reported by fishermen and divers suggests larger numbers being a more persistent feature of our waters.
'We will have to wait and see if this year's abundance of common octopus is - like the 1900 and 1950 outbursts - just a one year wonder.
"However, they have stuck around the last few years and the finding of a dead female with her hatched eggs in a deep fissure at Porthkerris two year ago was significant - they are breeding in our waters.'
A 'highly intelligent predator'
Octopuses are known for being effective hunters, with unique biological adaptions.
Ms Cocciardi said: "Octopuses are highly intelligent predators. "They have a parrot-like beak that can break into the shells of crabs and lobsters.
"They also inject venom that paralyses their prey and breaks down the soft tissue, turning it into a soup that they can suck out."
"They're also known for their ability to squeeze into tiny spaces and change colour to blend into their surroundings.
"They can instantly change colour from grey to yellow, brown, or green, blending into rocky coasts, shallow waters, and hide 200 metres below the water's surface."
Octopuses are climate change 'winners'
Alix Harvey, Ecology Laboratory and Research Aquarium Manager at the Marine Biological Association, said:"Globally cephalopods (Cephalopoda such as a squid, octopus, cuttlefish) are generally 'winners' when it comes to changing seas, even with issues like climate change and overfishing.
"Their short lifespan, rapid reproduction and intelligence allows them to exploit new environments."
What impact does the rising number of octopuses have on marine life?
Fishers in the region are reporting that their shellfish catch has plummeted, primarily due to the octopuses entering their crab pots, eating the shellfish and then exiting, leaving them with little to no catch.
A unique Devon bylaw requires some crab pots to have "escape holes" to protect young shellfish.
These holes typically allow young shellfish to escape but they are also providing a gap for octopuses to enter pots, consume the catch, and escape,The Devon and Severn Inshore Fisheries and Conservation Authority (IFCA) who is responsible for this unique bylaw, has responded with emergency measures, temporarily allowing fishermen to close escape hatches when specifically targeting octopus, provided they release any captured crabs or lobsters.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
BBC News
8 hours ago
- BBC News
How Devon and Cornwall warming seas are altering the food chain
Beneath the surface of the ocean is a world filled with a vast array of fauna and flora but scientists say "somewhat unusual" changes are taking place. Intensified by a marine heatwave in May, they say waters off the south coast of England are getting warmer and disrupting the food chain. "I'm not a scientist or anything like that," said Cornish snorkeler and underwater photographer Heather Hamilton."But because I've been in the sea so much over the last 20-odd years, I have seen changes, especially in the last two years." Ms Hamilton runs a a blog and Instagram page documenting the different species she sees in Cornwall, including different species of jellyfish as well as increases in octopus said the changes had also left her with a "mixture of emotions" from excitement to concern."You've got in the back of your mind, 'Is this a good thing?'" she said."It's a little bit worrying to think why is this happening all of a sudden in the last few years?" Ms Hamilton's observations in the sea are part of what marine ecologist Dr Bryce Stewart, from the Marine Biological Association in Plymouth, said were "dramatic changes" to the marine Stewart, who helped create the latest Sir David Attenborough documentary, said he was "very confident" changes in the marine environment were being caused by the warming of the recent months he said there had been some "somewhat unusual" changes off the coast of Devon and Cornwall, where a marine heatwave was most intense in have reported an "invasion" of octopus which is "decimating" the Devon shellfish octopus, usually found in the Mediterranean, are being increasingly found in lobster and crab pots off the is thought the octopuses are coming from Morocco, as fishermen there are reporting a shortage of the creatures. Dr Stewart said: "So there's a lot of species either turning up that we haven't had before or increasing abundance... and then of course we have other species that were more adapted to cooler water decreasing in abundance... and we see those changes right from the base of the food chain in the plankton to right to the top, to the tuna and sharks."He said the number of blue sharks off the south coast of England was currently the highest anglers had ever seen."We've been working with anglers, and they have datasets going back to the 1950s about their catch rates of blue sharks, they all let them go so don't worry about that, but the numbers now are the highest we've ever seen," he Stewart said changes were happening in the ocean "more dramatically" than anyone had predicted. Dr Stewart said a trip off the coast of Falmouth a couple of years ago was "one of the greatest days at sea" he had ever had – having travelled all over the the trip, he saw two fin whales, "thousands of dolphins", and also snorkelled with blue fin whale is the second-largest species of Stewart added: "It's the biggest creature I have ever seen, we estimated probably 70ft long, which is enormous right?"These things are now just off the coast, and I would encourage as many people as possible to go out and see them." The Devon Wildlife Trust said it was seeing changes closer to the shore, including colourful species of sea Cocciardi, marine nature recovery officer at the trust, said one citizen science project involved surveying rock pools at Wembury beach, in the South Hams, on a monthly basis. "That gives us a good indication of what changes year-on-year and month-on-month," she said."So for example, what we're seeing more in Wembury is... furrowed crabs, and sometimes hermit crabs - and those are more Mediterranean species, that are seen here more and more often." This spring has been the second sunniest spring on record. With sunshine levels high, and the vertical mixing of water limited by the predominance of easterly and north-easterly winds, a marine heatwave was recorded in the waters to the west of Ireland and through the Irish and Celtic seas in mid-MayThe phenomenon is defined as sea temperatures which exceed the seasonal threshold for more than five consecutive days. In the UK the marine heatwave threshold for May is 11.3C (52.34F). On 19 May, the average sea surface temperature reached 12.69C (54.84F). For Ms Hamilton, the sea is a "very special place" and growing up in the Isles of Scilly meant it was "kind of inevitable" she would be captivated by the ocean."Going in the sea and snorkelling is kind of like an escape from the world above, you're kind of putting your head under the water and you forget about all your worries in life," she said."It's just very calming and peaceful."Dr Stewart said if people engaged with marine environment more, they would be more likely to become passionate about protecting it."I'm going to echo the recent Ocean with David Attenborough film here," he said."What that showed us and what I've seen as well in my own research is that when we look after the marine environment, it has an amazing ability to bounce back."
BBC News
28-05-2025
- BBC News
Octopus boom in UK waters
Despite being called the common octopus, it's actually not very common to see these eight-legged creatures in UK fishers on the south west coast of England have noticed an increase in both the numbers and size of the cephalopods over the past few has meant there are fewer lobsters, crabs and shellfish for the fishers to catch and sell, because the octopuses feed on think it could be due to rising sea temperatures or that there aren't as many predators in the water, but say more research is needed. Why is this a problem? Fishers in the UK catch lobsters, crabs and shellfish using pots which they then pull up from the sea floor. But these pots have small openings which the octopuses can squeeze themselves into to feast on the animals inside for themselves. It means there are fewer crabs, lobsters and shellfish for the fishers to sell, but they can still get a decent price for the octopuses they catch. The main concern comes from scientists who are trying to figure out why this is happening and if there are any other consequences. What do the experts say? Carli Cocciardi, from the Devon Wildlife Trust, said: "We typically see two species in the UK, the common octopus and the curled octopus."The south-west of England is really the northern edge of the common octopus's range, so sightings here are significant."These are the species most likely to be involved in the recent increase.""This isn't the first time we've seen a spike. Similar increases were recorded in 1899, 1948, and again in 2022."The most likely cause is rising sea temperatures, which make our waters more suitable for species like the common octopus."Other factors could include changes in ocean currents or increased prey availability. "It's interesting that the gaps between these events are shortening, perhaps it's no longer a rare cycle but a sign of more permanent change."
The Guardian
22-05-2025
- The Guardian
‘Unprecedented' marine heatwave hits waters around Devon, Cornwall and Ireland
The sea off the coast of the UK and Ireland is experiencing an unprecedented marine heatwave with temperatures increasing by as much as 4C above average for the spring in some areas. Marine biologists say the intensity and unprecedented nature of the rise in water temperatures off the coasts of Devon, Cornwall and the west coast of Ireland are very concerning. As human-induced climate breakdown continues to raise global temperatures, the frequency of marine heatwaves is increasing. 'This is unprecedented because it is happening so early in the year,' said Dr Manuela Truebano, from the school of biological and marine sciences at the University of Plymouth. 'To see these temperature rises around UK waters at this time of year is quite sobering. Each time it happens we use the word 'unprecedented', and I am very concerned at the increase in prevalence and intensity of these marine heatwave events.' Temperatures in the sea off the south coast of Devon, Cornwall and Ireland have risen by between 2C and 4C above average temperatures for this time of year. Dr Dan Smale, of the Marine Biological Association, said the usual springtime water temperatures would be 11C-12C, but the waters were now at absolute temperatures of 15C-16C. The UK is increasingly being hit by marine heatwaves, with sea temperatures in June 2023 reaching their highest levels since records began. At the time the warming was labelled as 'unheard of'. Truebano said the rise in sea temperatures so early in the spring was even more concerning. The marine heatwave began in March and has continued for almost two months. If the sea temperatures continue to rise into the summer months there are fears of mass die-offs of fish and other marine life. Marine biologists say the impacts of the spring marine heatwave could be profound, including changes in the reproductive patterns of plankton, which in turn could lead to reductions in fish numbers later in the year. Smale said: 'It is a concern that these warming events are happening more and more in the UK and Ireland. Traditionally UK waters have not been affected, but these events are starting to happen more frequently and the associated temperatures are increasing. 'If this continues through the summer we would expect to see widespread biological impacts. This is a significant warming event.' Sign up to Down to Earth The planet's most important stories. Get all the week's environment news - the good, the bad and the essential after newsletter promotion The Met Office said the marine heatwave had lasted more than two months, from early March and continuing into May. 'It is significant due to its intensity and persistence,' it said. It said the increase in heat was the result of several overlapping factors including prolonged high-pressure systems which brought a dry, sunny spring and weak winds and waves, creating ideal conditions for warming. The sea began to warm from mid February – one month earlier than usual – and rose in temperature from a warmer baseline as the waters around the UK were already warmer than usual coming out of winter. Data shows marine heatwaves are increasing in frequency. A 2019 study found the number of heatwave days rose by more than 50% in the 30 years to 2016, compared with the period from 1925-54. Scientists said at the time the heat destroyed swaths of sea life 'like wildfires take out huge areas of forest'. Dr Jonathan Tinker, a marine climate scientist at the Met Office, said: 'With projections suggesting UK summer sea temperatures could rise by up to 2.5C by 2050, such events are likely to become more frequent, intense and longer-lasting. Marine heatwaves offer a glimpse into how changing ocean conditions could shape future weather conditions.'
