select search filters
roundups & rapid reactions
before the headlines
Fiona fox's blog

expert reaction to report from an independent panel investigating the North-East England crustaceans incident

A report commissioned by the Department for Environment, Food & Rural Affairs (DEFRA) investigates the unusual crustacean mortality in the north-east of England in 2021 and 2022.

This Roundup accompanied an SMC Briefing.


Dr Gary Caldwell, Senior Lecturer in Applied Marine Biology at Newcastle University, said:

“The report concludes that it is about as likely as not that a pathogen new to UK waters – a potential disease or parasite – caused the unusual crustacean mass die-offs, despite the fact that there was no direct evidence for the involvement of any pathogens, and that Cefas had previously dismissed the involvement of disease. The failure to evidence this conclusion is remarkably poor scientific practice.

“We agree with the Panel’s conclusion that the involvement of a harmful algae bloom is unlikely. However, the dismissal of pyridine involvement also ignores the chemistry of the molecule, including its propensity to adsorb to sediment particles and its capacity to remain for many years in the environment if protected from oxygen. The report also overlooks the fact that we detected pyridine in surface sediment fully 7 months after the mass die-offs, and that we have been prevented from taking sediment core samples to quantify pyridine levels in the deeper sediment. The Panel also failed to recognise the virtual elimination of the barnacle population from the Staithes long term monitoring site, which is positioned midway along the modelled trajectory of the sediment plume. Pyridine is a well-known and powerful antifouling agent that is used to kill barnacles.”


Prof Michel Kaiser, Chief Scientist at The Lyell Centre and Professor of Fisheries Conservation, Heriot-Watt University, said:

“The report addresses a wide range of plausible causes of the observed mass mortalities of crab and lobster. The panel used a logical decision framework to decide the likelihood of whether a particular pollutant or environmental issue had led to the mortalities. The report effectively concludes that there is no strong evidence to conclude what the actual cause of these mortalities might be, although a disease organism cannot be ruled out. It would seem prudent to devote more effort to monitoring crabs and lobsters for disease organisms in this region.

“My own reading of the pattern of deaths along the coast might suggest the gradual spread of a disease organism in a stepwise manner down the coastline and a little to the north of the Tees. The report would have benefitted from the inclusion of outputs that showed the modelling of residual tidal flow patterns and consideration of any extreme temperature or wind events that also might be factors leading to mortality, similar to mass wrecks of marine life that regularly occur after severe storms.”


Prof John Spicer, Professor of Marine Zoology, Plymouth University, said:

“The newly released report will no-doubt disappoint many in its inability to identify the ‘smoking gun’ responsible for this particular mass dying, although in having to consider such a large list of potential causes it draws attention to the ‘elephant in the room’ in all such reports – the ticking time bomb that is historical marine pollution combined with climate change”.


Prof Sir Colin Berry, Emeritus Professor of Pathology, Queen Mary University of London (QMUL), said:

“This looks to me as a good a study as it was likely that you could set up faced with the data that provoked it – I don’t know the people involved but they clearly have (between them) the necessary skills and knowledge base to examine and draw conclusions from the evidence presented to them.

“The pattern of exclusions of chemical causes is clear – all likely possibilities seem to be excluded.  It seems to me that a “new” pathogen is much the most likely factor in this (these) event(s).

“The paragraph in section 5.4 of the report concludes:

The absence of any observed toxic chemical associated with run-off, and the lack of any reason for the Teesside reason to have higher levels of such chemical run-off than other settings across the UK, led the panel to conclude that it is very unlikely that chemicals associated with run-off from shore caused the unusual crustacean mortality.

“I am sure that is right.”



Independent Expert Assessment of Unusual Crustacean Mortality in the North-east of England in 2021 and 2022’ was published at 12:00 UK time on Friday 20 January 2023.



Declared interests

Prof Sir Colin Berry: “I have no conflicts.”

Prof Michel Kaiser is employed by Heriot-Watt University. He currently has a £4.5M portfolio of research funding, the majority of which is from the UKRI-NERC, other funding includes UK fishing entities, UK retailers, Fishmonger’s Company, CISCO, DEFRA, The Children’s Investment Fund Foundation. He is a trustee of the charities Fishing into the Future, and the Scottish Fisheries Museum Trust Ltd.

For all other experts, no reply to our request for DOIs was received.

in this section

filter RoundUps by year

search by tag