20-05-2025
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.
