A fresh report has said a chemical that some believed caused mass wash-ups of dead crustaceans from the North Sea is very unlikely to have caused the fatalities.

Mass wash-ups of dead marine life on the Teesside coast were first reported in October 2021, with some scientists and fishermen believing the chemical compound pyridine was the cause.

Some argued the chemicals disturbed by dredging on the Tees riverbed were responsible, but a report released on Friday (November 3) using new scientific tests said it was “very unlikely” pyridine caused the marine deaths.

It backs up the findings of the Crustacean Mortality Expert Panel (CMEP) report published in January which also said pyridine was not likely (less than a 10% likelihood) to have been the cause.

But at the time the independent panel, convened by Defra, had no way to test for pyridine levels in animal tissue and instead used an adapted test.

Since, a new method to look for the compound in animals has been developed and used for the latest report by Cefas (the Centre for Environment, Fisheries and Aquaculture Science).

Cefas took frozen samples of the dead crabs and lobsters washed up in October two years ago and found “low levels of pyridine” in all of the samples when running their new test.

The Northern Echo:

The report concluded: “Data presented in this study provide additional evidence supporting the conclusion that it is very unlikely that pyridine, as a single chemical entity, was the cause of the crab and lobster mortalities during autumn 2021.”

It does not comment on the likelihood of other causes of the wash-up.

The new method will be used in analysing any future mass mortality events.

It backs up the CMEP report from January which also said pyridine was unlikely to be the case. That probe was unable to find a single cause for the mass wash-ups, leaving fishermen caught in the middle of storm over the deaths still lacking clarity over their cause.

A February 2022 report into the wash-ups had said the deaths were due to a “naturally occurring harmful algal bloom”, but that claim was backtracked on in the CMEP investigation.

Fishermen previously told how they’ve struggled to make a living with depleted numbers of sea life following the deaths.

The Northern Echo: Fisherman have previously expressed their concerns and how they have suffered from the wash-ups.Fisherman have previously expressed their concerns and how they have suffered from the wash-ups. (Image: SARAH CALDECOTT)

Rumours that pyridine caused the wash-ups caused a political storm amid controversy around the dredging of the Tees.

On Friday Tory politicians welcomed the report saying it was time to put “baseless politically motivated attacks” to bed.

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Jacob Young, Conservative MP for Redcar, said: “For anyone concerned about our coast and marine life, and for the fishermen who have lost their livelihoods after the initial die off, this has been an incredibly difficult time.

“I hope that with the conclusion of this report, we can not only settle the legitimate questions raised by concerned members of the public, but also put to bed the baseless politically motivated attacks that I and others have had to face.

“Now is the time for us all to come together, to work for a brighter future for Redcar and Cleveland and to see our shared ambition of jobs in prosperity through our Freeport realised.”

Sir Simon Clarke, Conservative MP for Middlesbrough South and East Cleveland, added: “This is the third major scientific study to discount the idea that pyridine was the cause of the 2021 sealife die offs.

“For too long, people with a political agenda against our Freeport have been pushing a toxic narrative of conspiracy and betrayal which is utterly baseless, and deeply damaging to jobs and growth on Teesside.  

“With the independent experts at the Centre for Environment, Fisheries and Aquaculture Science now issuing their study, I hope local opposition politicians who have been stoking this agenda will drop their pseudoscience and back the best opportunity for Teesside in over 50 years.”

The Echo has contacted Teesside's left MPs.