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Crab deaths more likely caused by industrial toxins than algal bloom – study

A mass die-off of marine life on the North East coast saw crustaceans washed ashore between October and December 2021.


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, new research has claimed.

A mass die-off of marine life on the coastline from Hartlepool to Whitby saw crustaceans washed ashore between October and December 2021, with dying creatures “twitching” and displaying lethargic behaviour.

A spokesperson for the Department for Environment (Defra) said earlier this year they had concluded “a naturally occurring harmful algal bloom” was the most likely cause of the deaths, following a “thorough investigation”.

But a report commissioned by a number of North East and Yorkshire fishing associations has now instead concluded that “poisoning by industrial toxins” was the more likely cause.

The study was ordered by the North East Fishing Collective (NEFC) – made up of fishing industry representatives in the impacted area – and funded by The Fishmongers’ Company, with research carried out by academics from Durham, Hull, York and Newcastle universities.

NEFC said it used crowdfunded money to commission marine pollution consultant Tim Deere-Jones to look into the mass die-offs.

The report said: “Over the past couple of years, several mass mortality events have affected marine life off the English north east and Yorkshire coastlines.

“Media reports have highlighted some of these, especially the unprecedented numbers of dead and distressed crabs washed up near Teesside in October 2021.

“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.”

The report said the deaths had had a “dramatic” impact on the fishing industry and coastal communities.

An official report earlier this year by the Environment Agency, Centre for Environment, Fisheries and Aquaculture Science, and the Marine Management Organisation did not identify any “single, consistent, causative factor”, but a harmful algal bloom in the area at about the same time was identified as being of significance.

The NEFC report said: “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).”

Protest over crab deaths
Fishing crews staged a protest near the mouth of the River Tees earlier this year demanding a new investigation into the mass deaths of crabs and lobsters (PA)

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 researchers carried out a study testing the responses of crabs to pyridine, and found the chemical “can induce exactly the same twitching behaviour as seen in affected Teesside crabs”.

The report concluded: “Our preliminary evidence suggests that crab deaths are more consistent with poisoning by industrial toxins than by natural algal toxins.”

Joe Redfern, co-founder of Whitby Lobster Hatchery, marine biologist and chairman of the Whitby Commercial Fishing Association, said: “The results from the investigations should change the way we think about not only the recent mass mortality events that have impacted our coastline, but also the way we think about dredging and marine pollution all over the world.”

Prime Minister Liz Truss said she “would need to look into the issue” of marine life deaths during an interview on BBC Radio Tees on Thursday.

She added: “I know the Environment Agency are looking at the issues but I will certainly be raising that with the Environment Secretary.”

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