Ministers and MPs leaned on government officials investigating the death of thousands of crabs and lobsters in north-east England to deny that dredging by a ports giant was a likely cause, openDemocracy can reveal.

openDemocracy has obtained a large number of documents through multiple Environmental Information Regulation (EIR) requests that reveal politicians pressured investigators to rebut an independent report that pointed the finger at the practice.

The chair of the Whitby Fishermen's Association, James Cole, has previously accused the authorities of a ‘cover-up’ to protect the government's plans for the expansion of the politically sensitive freeport in Teesside, which will require dredging. Similarly, Labour councillor Alma Hellaoui has accused the government department of a “cover up of the real issues that face us”.

In October 2021, dead crustaceans started to pile up along the North Yorkshire shore, first along the Tees Estuary near Redcar and then as far south as Scarborough, taking in major fishing towns like Whitby.

An investigation by the Department for Environment, Food and Rural Affairs (DEFRA), with the Environment Agency, the Marine Management Organisation and the Food Standards agency, suggested a naturally occurring “algal bloom” was probably responsible.

Locals, however, were not so sure. Cole’s association commissioned Tim Deere-Jones, a marine pollution researcher and consultant, to conduct an independent review of the event. He concluded: “Pyridine and its derivative compounds are currently the most likely causative factor behind the mass mortality of marine species along the north-east coast.” Pyridine, the report explained, is a toxic chemical compound “released into the environment as a waste product discharged from industrial processes”.

His report described how dredging, such as had occurred in the Tees Estuary, disturbs and releases the compound, and proposed that this was a likely cause of the marine mass mortality.

Angry ministers and devastated fishing communities

Deere-Jones’ conclusion angered some ministers and MPs. Meeting notes from February 2022, released to openDemocracy by the UK Health Security Agency (UKHSA), confirm that “relevant agencies” were scrambling to issue a “rebuttal” to the independent report following pressure from ministers seeking to shift the blame away from dredging activities.

A few days after ministers pressured agencies to kick back against the dredging claims, more dead crabs and lobsters washed up along the north-east coast. Defra responded by saying it would conduct “additional sampling”.

Nevertheless, government agencies have continued to maintain that an algal bloom probably caused the deaths, despite evidence from released documents of high levels of uncertainty about this conclusion.

And DEFRA has refused to release email correspondence from its ministers Victoria Prentis and George Eustice relating to the incident, on the grounds that it was “manifestly unreasonable” and not in the public interest to publish the emails.

Meanwhile, the fishing communities affected by last year’s incident are still reporting lower-than-expected catches and the government decision to stick to the line that this was a naturally occurring incident provides the excuse to deny much-needed financial support to the struggling fisheries whilst simultaneously allowing the dredging in the Tees Estuary to continue uninterrupted.

In June, the MP for Stockton North, Alex Cunningham, introduced a debate in Parliament to discuss the case. Prentis again ruled out dredging as the cause, while also claiming: “We may never know for sure what caused the event.”

DEFRA told openDemocracy the investigation was “a complex area of research”.

A deep dive: did dredging cause this chaos?

Documents released by PD Ports to openDemocracy through EIR requests cast serious doubt on DEFRA’s continued insistence on ruling out dredging as a cause.

They reveal that huge amounts of contaminated sediment from the bottom of the Tees were dredged in the same weeks that tens of thousands of crabs and lobsters started washing up dead along the nearby coastline.

To bolster its algae theory, DEFRA provided a satellite image of a possible ‘bloom’ that appeared in the Tees Estuary between 9 and 15 October 2021. However, the image came with the caveat that some “uncertainties” remained on how to interpret “satellite data in near shore waters”. And openDemocracy has found that the timing and location of the satellite image coincides with PD Teesport’s dredging of over 317,000 tonnes of sediment, which was later disposed of at sea.

Internal documents released to openDemocracy suggest that agencies did not in fact rule out man-made activities as a cause of the bloom. Minutes of a meeting from December 2021 between the key agencies involved in the investigation, labelled “official sensitive”, noted: “This event is generally natural, but it does not mean it could not be influenced by human intervention.”

Another email between investigators at the UK Health Security Agency suggests: “Released nutrients from e.g. dredging could theoretically influence algal bloom.”

Other documents reveal that the Environment Agency (EA) seemingly ruled out both “algae toxins” and a “natural event” in a November 2021 presentation. The Powerpoint noted that the “behaviour and longevity mean it is unlikely that a ‘natural event’ caused the deaths”. The presentation noted that dredging was “not ruled out yet” and was the “most serious line of enquiry to be investigated”.

The released documents also show that the EA was aware of the high level of Pyridine in the dead crabs, with test results of crabs impacted by the pollution event showing Pyridine levels hitting 439.611mg/kg – a figure that is an eye-watering 7,000% higher than crabs sampled in Penzance during the same period.

The EA noted that: “Pyridine levels were the highest of all contaminants recorded.” Such high levels led to concerns being raised by the Food Standards Agency (FSA), which noted that this may have been the “root cause of the die-off”. The FSA also commented: “This level concludes that acute risk cannot be excluded.”

According to another document, also marked “official sensitive”, further testing of the dredging site was ruled out for financial reasons, despite repeated calls from the fishing community, with civil servants noting: “Retesting of the sites can’t occur because cost would be £50,000.”

A DEFRA spokesperson said: “Defra led a comprehensive investigation into the cause of dead crabs and lobsters that washed up on the north-east coast between October and December last year.

“Government scientists carried out extensive testing for chemicals and other pollutants, including pyridine, but concluded a naturally occurring algal bloom was the most likely cause. It’s a complex area of research – and we will continue to work with universities and other experts to understand it better.”