Octopuses have long captivated humans with their alien-like appearance and bizarre anatomy.
This spring, the cephalopods have been baffling, delighting and enraging fishers in English waters as an unprecedented marine heatwave has led to a surge in their numbers.
The boom in octopus catches began to be seen in March in east Cornwall and Devon – as sea temperatures rose by between 2C and 4C above average spring temperatures.
The hauls have been a boon for fishers. At Brixham market, where most of the catch is sold, tens of tonnes of octopus is being traded every day. Octopus fever has taken over the town; Octavia the octopus, a cephalopod-shaped light usually switched on at Christmas, is being turned on every night; while a nearby cafe has decorated itself with an octopus mural.
Barry Young, the managing director of Brixham Trawler Agents, said 36 tonnes of octopus came through the market on Thursday – compared with about 200kg this time last year.
“It’s a financial bonus for the fishermen,” Young said. “They’re grabbing it with two hands while they can. The boats, they fish for certain species, we fish for ‘bottom fish’, which is called a demersal species. We would catch plaice, dover sole, brills, turbots, anything sort of bottom-dwelling.
“Luckily for us and the fleet that we deal with, the octopus seems to be a bottom-dwelling fish as well.”
Ian Perkes, who has owned a fish merchant in Brixham harbour for 49 years, said it was the first time in his career he had seen the giant molluscs.
“It’s down to climate change because it’s only this year that they’ve been here,” he said. “We’ve not seen them before, this time last year, they were on the French side of the water and the French were filling up with them.”
Perkes said octopuses were normally caught off the coast of Morocco and Mauritania, where it is a “massive, massive business” but they have been coming north as the water off the coast of England was much warmer.
The surge in octopus numbers has been a bonus for English fishing because there is no quota and a big market, especially in Spain, fetching £8 a kilogram at auction. The 22-tonne catch brought in on Tuesday would be worth about £170,000, Perkes explains. Approximately 70-80% of the fish and seafood caught is sold abroad.
“They’re a shot in the arm for the fishermen, like a massive bonus, because there’s no quota. They’re making incredibly good money,” Perkes said, adding that the octopuses were being swept up across the industry.
“They’re getting caught in all methods of fishing,” he said. “Caught in cuttlefish pots, in crab pots by trawlers, by the beamers. The seabed is full of them.”
The flip side to the boom in the UK is that the industry is struggling in Spain, where many companies have processing facilities and employ hundreds of people in Morocco and Mauritania.
And not everyone in the UK industry is pleased. There was some tension among fishers specialising in crab and lobster when they discovered the octopuses entering the pots and eating the shellfish inside.
The octopus – which has nine brains and three hearts – uses its beak to break the crab or lobster shell. It then injects enzymes that help dissolve the meat before sucking it out.
“Some of the boats have seen that, where the octopuses are prolific in certain areas, they have seen a dramatic drop off in crab and lobster,” Young said.
The Devon and Severn Inshore Fisheries andConservationAuthority (D&S IFCA) enforce a bylaw requiring “escape gaps” to be fitted to crab and lobster pots to enable undersized shellfish to escape – a conservation measure to protect juvenile crabs and lobsters and allow them to escape.
It is through these escape hatches that the fishers believe the octopuses are entering and leaving after they have eaten the creatures within. The D&S IFCA said the holes could be closed if fishers were trying to catch octopuses only, and it was working on trying to find a long-term solution.
Marine biologists said the spike in marine temperatures this spring was unprecedented. It began in early March and is continuing into the end of May.
As human-induced climate breakdown continues to raise global temperatures, the frequency of marine heatwaves is increasing, with the UK being subjected to spikes in sea temperature more frequently.
According to Dr Marta Marcos, at the Mediterranean Institute for Advanced Studies in Mallorca, Spain, who led a study into marine heatwaves, half of the sea warming since 2000 would not have happened without global heating.
Carli Cocciardi, a marine nature recovery officer at DevonWildlifeTrust, said there had been a surge in octopuses in English waters recorded in the 1900s, the 1950s and briefly in 2022.
“We’re unsure why this surge is happening,” she said. “But the main reason seems to be warmer waters, so climate change, a sea temperature rise. It could be also changes in prey availability or ocean currents.”
Cocciardi said they were medium to large octopuses that could grow up to 1.3 metres in length and were “very intelligent animals”.
She said there was no quota and as it was a new phenomenon it was uncertain what would happen in terms of management. But she added the authorities would “make sure it was sustainable” if it became a permanent feature in English waters.
“We’re just going to have to keep an eye on it,” she said.