Last autumn dead shellfish started washing up on North East beaches and a row has since ensued about why this happened.
Meanwhile local fishermen reported they are struggling to make end meet as local fish supply has dwindled.
The Government Department for Environment, Food and Rural Affairs (DEFRA) said the mass crustacean deaths were down to a natural 'algal bloom'.
However the North East Fishing Collective (NEFC), made up of fishing industry representatives in the impacted area, commissioned an investigation carried out by academics from Durham, Hull, York and Newcastle universities.
On Thursday 29 September they reported that the deaths of thousands of crabs and lobsters washed up on North Sea beaches are more likely to have been caused by "industrial toxins" than an algal bloom.
How did we get to this point?
Local fishing industry reports a 95% decline in their lobster and crab catch.
No official theories have, as yet, been given for the cause.
5 November 2021-
DEFRA begin investigating the situation.
27 November 2021-
They decide to focus more on whether disease or a natural event could have been responsible.
A retired marine biologist from Teesside believes he has cracked the case and calls for the country's top testing lab to get involved.
David McCready thinks that dredging - the process of excavating river or sea beds of debris - is to blame.
2 February 2022-
It comes as DEFRA releases its report. It considers the deaths of the crabs and lobsters potentially resulted from a naturally occurring harmful algal bloom.
The report said: "From the evidence found during the investigation it is unlikely that chemical pollution, sewage or infectious aquatic animal diseases were the cause of the deaths.
"No traces of chemical contaminants have been found that could have caused an event of this scale.
"A review of dredging activity and water samples found no evidence of a link between the disposal of dredged sediment and the deaths."
DEFRA said it is doing "additional sampling of crab and lobster" following more reports of dead shellfish washing up on North East shores.
In a statement it said: “Further scientific work is required to continue to examine the ongoing impact of this incident and we will continue to update industry on next steps as work continues.
"We are aware that there have been reports of further dead or dying lobsters and crabs found in a small number of pots along the North East coast this week, and will be undertaking additional sampling of crab and lobster within the incident area to investigate.”
Climate action group, Ocean Rebellion, stage a protest in London by leaving piles of dead crab on the streets.
The group were campaigning against DEFRA’s decision to close the case on the thousands of dead crabs and lobsters that washed up on North Eastern shores.
They blame the industrial process of dredging for the mass deaths and said in a statement on their website: "The severity of the die-off sparked an Environmental Agency and DEFRA inquiry.
"After checking all the usual suspects, sewerage, cables and the like, the report blamed an ‘Algae bloom’, a conclusion described as ‘rubbish’ by local fishers (who know the local environment).
"The same report did reveal an important finding – the presence of extremely high levels of Pyridine, a toxic chemical that’s prevalent in many industrial processes – especially in factories along the banks of the River Tees.
"The levels of Pyridine found in the crab corpses examined by DEFRA were ten times higher than crabs found in other parts of the UK."
10 May 2022-
Clumps of dead seaweed have also been seen.
DEFRA confirm they are monitoring the finds.
19 May 2022-
Fishing crews stage a protest in Teesport, Middlesbrough, near the mouth of the River Tees, demanding a new investigation into the mass deaths of crabs and lobsters in the area.
1 June 2022-
They included licensed dredging, chemical contamination, activities related to offshore wind farms, the presence of algal blooms and aquatic animal disease.
No "single, consistent, causative factor" is found, according to the report from the government agencies, though it concluded it was unlikely dredging, chemical or sewage pollution or animal disease were the cause.
29 September 2022-
The report said: "There is general agreement that these events are caused either by natural toxins released during an unusually large offshore harmful algal bloom; or industrial toxins that have accumulated offshore and could be released from marine sediments by dredging or by storms.
"We find that satellite imagery does show a marine algal bloom off Teesside at around the time of the October 2021 mass mortality event.
"However, that bloom was not unusually large (several larger blooms occurred in 2021 and 2022 without causing mass die-offs)."
The researchers also said harmful algal blooms usually kill a broad range of organisms, but the Teesside events disproportionately affected crabs and lobsters, with the crabs showing "unusual twitching behaviour".
They said pyridine - a common industrial chemical - has "come under suspicion because high levels have been found in dead crabs".
The report concluded: "Our preliminary evidence suggests that crab deaths are more consistent with poisoning by industrial toxins than by natural algal toxins."
What is dredging?
Dredging is the process of excavating river or sea beds of debris and sediment.
The build of sediment is a naturally occurring process where silt, sand and other debris accumulate on the bottom of rivers, lakes, canals or streams over time.
An excessive build-up of debris and sediment can cause a series of issues like reducing the depth of the waterways and preventing the passage of ships.
What is Pyridine?
Pyridine is a colourless liquid chemical with an unpleasant smell.
It can be made from crude coal tar, the condensate from coking ovens in the steel industry.
What is an algal bloom?Harmful algal blooms are the rapid growth of algae or cyanobacteria which can cause harm to animals, people, or the local eco system.
It can look like foam, scum, paint, or mats on the surface of water and can be different colours.
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