'Are they going to take over?' - Spider crabs multiply off Norfolk coast

A spider crab on the wreck of the Rosalie off the coast at Weybourne in north Norfolk.

A spider crab on the wreck of the Rosalie off the coast at Weybourne in north Norfolk. - Credit: Mark Crame

North Norfolk fishermen have been catching unprecedented numbers of a species of crab native to warmer southern waters - in another sign of the impact of climate change on the county.

The spiny spider crab, normally found in the Mediterranean Sea, the northeast Atlantic and on the south and west coasts of England, has been migrating northwards due to warmer sea temperatures.

Catching one in the North Sea used to be a rare occurrence - but this year they have been turning up in fishermen's pots from Cromer to Weybourne.

John Davies, 57, a Cromer fisherman, said: "It's quite a new phenomenon. We'd had the odd one or two before but this year there seem to be quite a lot more.

Cromer fisherman John Davies.PHOTO: ANTONY KELLY

File photo of Cromer fisherman John Davies, who said the appearance of spiny spider crabs on the north Norfolk coast is "quite a new phenomenon". - Credit: ANTONY KELLY

"I've caught numbers in the mid-teens where before you never saw one at all."

Henry Randell, another Cromer fisherman, said: "A spider crab caught off the coast used to be extremely rare.

"You might get one or two along the coast. If you caught one people would be talking about it."

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Mr Randell, who is 28-years-old and has been fishing for 12 years, had never seen one before.

"But I've caught eight myself this year," he said.

Spiny spider crab

One of the spiny spider crabs caught this year by Cromer fisherman Henry Randell. - Credit: Henry Randell

"The gear we use isn't for spider crabs, they can't get in the pots so easily, so what we're catching is only a fraction of what's down there," he added.

In southwest England there is a commercial fishery for spider crabs, with most of the catch exported to France and England.

But Mr Randell said that for such fishing to develop in north Norfolk the fishermen would have to change all their gear.

"We don't want to see spider crabs, because we're fishing for brown crabs," he said.

"Are we going to see more and more every year? Are they going to take over? That's the concern."

Spider crabs

Two of the unprecedented number of spiny spider crabs caught this year off the north Norfolk coast. - Credit: Supplied

Mr Davies, who has been fishing on his own boat for 40 years, does not believe the spider crabs will have a major impact on the regions's crab and lobster fishing industry.

"I don't think they'll have any effect whatsoever," he said. "They're not as strong as our crabs. I'd imagine our traditional crabs will deal with them quite easily."

He did say that the patterns of Cromer crabs have changed slightly over the years, however, and warmer waters mean they do not hibernate for as long as they used to.

Alastair Grant, professor of ecology at the UEA's School of Environmental Sciences, said: “Spider crabs are more usually found in the south and west of the British Isles. 

"Climate change is leading to warmer sea temperatures and for some time now fish and shellfish have been expanding their geographical ranges northwards. So it isn’t a surprise that spider crabs are starting to turn up on the Norfolk coast.“

Mr Grant also anticipates that the spider crab will "coexist with our more familiar Norfolk species, just as it does in southwest England".

Chris Taylor snorkelling with his camera.

Chris Taylor snorkelling with his camera. - Credit: Chris Taylor christaylorphoto.co.uk

Chris Taylor, a Sheringham based photographer who frequently dives in the waters off the north coast, said the appearance of the spider crabs is "happening fairly quickly" and that most of them have been caught off West Runton.

Fishermen he spoke with caught none last year or the year before but have been catching multiple spider crabs this year.

Mr Taylor has not seen one himself yet this year, but said he wanted to film them.

An indication of the apparent suddenness of spider crabs appearing around Norfolk is a page on the Wildlife Trust's website which states the crustaceans are "absent" from the North Sea.

'Unlikely to take over'

Ron Jessop, senior marine science officer at the Eastern Inshore Fisheries and Conservation Authority (IFCA), based in King's Lynn, said the number of spider crab being found on the north Norfolk coast is "still low" compared to the southwest.

"Fishermen are catching one or two a day, not dozens or hundreds," he said.

Addressing concerns that spider crabs could displace the brown crab, known locally as the Cromer crab, Mr Jessop said he has spoken with colleagues in the southwest who have seen no indication that spider crabs take over.

He said it was possible that the spider crabs are currently migrating inshore as they normally live in deeper water.

"They could compete for food with brown crabs but we're not seeing the numbers that would indicate this is happening," he said.

"Normally, spider crabs won't out-compete brown crabs," he added. "Spider crabs are slow moving, less robust and less aggressive than brown crabs."

Crab facts

Cromer crabs are brown crabs, known scientifically as Cancer pagarus. They are found from Scandinavia to Portugal and have been caught off the north Norfolk coast for centuries.

They are hauled in with pots during the crabbing season which spans eight months of the year, with the peak, depending on the weather, lasting from March until July.

The spider crab, meanwhile, is also known as the European spider crab, or its scientific name of Maja squinado.

It is large and orange with long spindly legs (hence the name) and a body of up to 20cm long.

They eat seaweed, mussels and starfish.

It is a migratory crab, traditionally found in the northeast Atlantic and the Mediterranean Sea.

They migrate in autumn, from shallower coastal waters to the deeper offshore sea and back again, with some crabs covering 100 miles in eight months.