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What killed the Teesside crabs?

What killed the Teesside crabs?


Since 2021 dead crabs and lobsters have been washing up along England’s north east coastline. It has left the fishing industry demanding answers about what caused the die-off.

“A row has broken out between government campaigners and local fisherman as thousands of dead crabs and lobsters have been washing up on beaches across Teesside and North Yorkshire since 2021.”

Sky News

Along England’s northeastern coastline, from Hartlepool to Scarborough, crabs and lobsters have been dying in huge numbers.

And the effects of the “die-off” are being felt right up the food chain…

“Most of the grey seal pups last year born in the northeast either had to go into rehab or were put to sleep… and you know what, it’s absolutely heartbreaking.”

Channel 4 News

“Logs obtained from local fisheries officials show nearly 50 wash-ups of dead marine life from seals and seabirds to shellfish in the 12 months since the last die off ended in December 2021.”

Sky News

The impact is devastating both for the health of sea life and for the local fishing industry who have warned it could be catastrophic for their livelihoods.

“There’s families walked away from it, my brother and his son, they sold their boat this year and have come out of the industry after a lifetime, generations, they gave it up because they were feared that another die off would finish us and if we do have another die off it will finish me.”

Skipper James Cole speaking to Channel 4 News

So they’ve been looking for answers and more than year on, a row is still raging about what exactly caused so many crabs and lobsters to die.


After the die-off, the Department for Environment, Food and Rural Affairs – or Defra – led lengthy investigations which included the Environment Agency and the Marine Management Organisation.  

It concluded that the most likely cause of the die-off was a naturally occurring “algal bloom”.  

Defra went on to claim that although it was devastating, it couldn’t have been prevented.

But members of the local fishing industry have their own theory.

“Fishermen, campaigners and scientists say the prime suspect killing crustaceans is likely to be pyridine, a toxic byproduct of generations of Teessides steel and chemical industries.”

Channel 4 News

After Defra’s report came out, the North East Fishing Collective launched a crowdfunding appeal and raised enough money to commission scientists from Newcastle, York, Hull and Durham to do their own investigation.

Its conclusion disagreed with the government’s investigation and supported the theory of the local fishing industry, that a toxic chemical called pyridine could have killed thousands of crabs in the region. 

It suspected that dredging – the removal of sediment and debris from the Tees riverbed – had released the industrial toxins. 

Here’s Dr Gary Caldwell, a marine biologist at Newcastle University, speaking to Channel 4 News about Defra’s investigation…

“In my view it’s an almost untenable position to take and the amount of evidence that’s building up, the fact that we can measure pyridine here, the fact that we know how it’s going to move down the coast, the fact that we know how it poisons the crabs and the timings all match up…”

Dr Gary Caldwell, marine biologist at Newcastle University, speaking to Channel 4 News

But Defra stood firm on its findings, insisting it had done extensive research. 

“The government line is unchanged. Sea algae is the probable cause of this disaster, not chemical pollution… but it says it will study this new research carefully.”

Channel 4 News

Why would it be a problem if dredging was to blame?


In March 2021, as part of the government’s Spring Budget, it was announced that Tees Valley would get Freeport status – a designated area that gets economic benefits like tax breaks.

“These old steel manufacturing sites are going to be taken down and blown up, making way for some of the world’s largest investors. The Tees Valley Mayor Ben Houchen who has just been reelected with a huge 75 per cent of the vote says he hopes to attract some of the world’s biggest companies to Teeside.”

LBC News

The government says the freeport will be the largest in the UK, creating more than 18,000 jobs, and bringing benefits to the economy worth more than £3 billion over the coming years. 

But in order to construct the freeport, dredging was needed in the mouth of the River Tees to maintain channels for ships.

And it’s this dredging that the fishing industry believes has released chemicals that contributed to the die-off.

“None of us, nobody in the Northeast Fishing Collective is against the freeport of course we want jobs around here but it shouldn’t have been a freeport at the sacrifice of the fishing industry, of the ecosystem.”

Stan Rennie, Hartlepool fisherman, speaking to Sky News


In October 2022, the House of Commons Environment Committee spent a day reviewing the evidence presented by both sides.

It didn’t call for dredging to be halted, but did urge the government to re-examine the competing theories. 

In response, Environment Secretary Therese Coffey formed an independent panel of scientists to look at whether the deaths are down to nature or industrial poison. 

By December, protesters turned up outside the freeport site wearing masks with the Conservative mayor’s face on, calling for the dredging to halt.

“We wanna pause the dredge until it’s proven that it’s completely safe and if necessary, all sediment to be taken to landfill… so we’re here today to ask Ben Houchen and everyone dredging in the most toxic river in the whole country to do it responsibly and protect the North Sea.”

Protester speaking to Teesside Live

But the dredging hasn’t stopped. In fact, a new phase has just begun. 

Last month, the independent panel of scientists put together by Therese Coffey said it is “very unlikely” that dredging was the cause, and maintained Defra’s finding that a disease or parasite new to UK waters may have been responsible. 

But scientists may never be able to identify the exact cause of the die-off, leaving the local fishing industry fearing that it could happen again.

This episode was written and mixed by Imy Harper.