Disease or parasite 'new to UK' could be cause of mass die-off of crabs in North Sea
A panel set up to look into the cause of dead and dying crabs being washed up on beaches in the North East and North Yorkshire has said a disease or parasite new to the UK could have been responsible for the mass die-off.
The panel has also said dredging is “very unlikely” to have caused the deaths of thousands of crabs and lobsters.
A mass die-off of marine life along 70km of the coastline from Hartlepool to Whitby saw crustaceans washed ashore between October and December 2021, with dying creatures “twitching” and displaying lethargic behaviour.
The Department for the Environment, Food and Rural Affairs (Defra) has previously blamed an algal bloom for the deaths, while a report by university academics, commissioned by the North East Fishing Collective (NEFC), suggested the chemical pyridine could be a contributory cause.
The independent panel investigated a number of possible causes but was unable to conclusively say what caused the deaths.
It considered a range of causes, including a potential disease or parasite, a harmful algal bloom, chemical toxicity including pyridine, and dredging which could have released a toxic chemical.
It said it was “as likely as not” that a pathogen new to UK waters, which could be a potential disease or parasite, caused the crab deaths.
“Although there is no direct evidence of a novel pathogen – a disease or parasite – it would explain the key observations including mortality over a sustained period and along 70km of coastline, the unusual twitching of dying crabs and the deaths being predominantly crabs rather than other species,” the panel said in a statement.
“It is also possible that a combination of factors lead to the unusual mortality, rather than one of the factors the panel considered.”
The report, published on Friday 20 January, found:
It is about as likely as not that a pathogen new to UK waters, which could be a potential disease or parasite, caused the crab mortality.
It is unlikely that a harmful algal bloom or that a loss of oxygen in the water associated with the algal bloom caused the crab deaths.
It is very unlikely that pyridine or another toxic pollutant caused the crab deaths.
It is very unlikely that maintenance dredging, as required to keep the port open, was the cause
It is extremely unlikely that capital dredging, which started a year after the die-off, could have been a cause
The panel was made of experts from academia and industry and was chaired by Defra’s Chief Scientific Adviser, Gideon Henderson with input from the Government Chief Scientific Adviser, Sir Patrick Vallance.
Tammy Horton, a scientist investigating the possible role of a pathogen or disease, said: “I wish we could have come up a conclusion...We have ruled things out but we haven’t been able to confidently rule things in."
Crispin Halsall, who investigated the role of chemical pollutants, said the pyridine story could be “put to bed”.
Sir Patrick Vallance, Government Chief Scientific Adviser said: “For a complex issue like this it is important to have a range of experts involved who can offer independent challenge and analysis.
"Whilst with the current data there cannot be a definitive answer, the options for possible causes and an analyses of likelihood are clearly laid out in the report."
Gideon Henderson, Defra Chief Scientific Adviser said the panel had been unable to identify a "single clear cause" but had been able to point to those "more likely" to explain the outbreak.
It was one of the biggest news stories of our time - and it's still not over. So what did Boris Johnson know about Downing Street’s notorious parties? With fresh revelations from our Number 10 sources, in their own words, listen to the inside story...