A fisherman from Whitby has told ITV News Tyne Tees his industry has been "decimated" by the mass deaths of crabs and crustaceans in Autumn 2021 and said it had been "absolute torture".
James Cole, the chairman of the Whitby Fisherman's Association has joined calls for the government to halt dredging in the River Tees and reopen an investigation into the deaths.
It comes after the publication of a report on Thursday 29 September, which claimed to have evidence that an industrial chemical and dredging may have been the cause.
Mr Cole said: "It decimated the stock and only now have we started to see a little bit of improvement over the past month, but before, what we have just gone through was absolute torture.
"We’ve lost a lot of men out of the industry, crew members, a lot of boats are going with less crew than what they normally would.
"We’re having to work longer hours and put more gear in to try and keep our catch rates up, just so we can survive."
Marine Biologist and member of the North Eastern Fishing Collective, Joe Redfern, joined the fishing community to commission the report by four universities.
It concluded that the toxic chemical, pyridine, which could have been released by dredging, was more likely to have caused the crab deaths than an algae bloom.
The Department for Environment, Food and Rural Affairs (Defra) said it was a "complex" issue, but maintained the findings of its own investigation that the algae bloom was to blame.
Mr Redfern said: "The results seem really clear. We’ve found presence of pyridine in the sediments and we’ve shown the potential of the pyridine to cover the whole impacted area and we now know just how toxic and deadly pyridine is to crabs.
"We’re calling on the government to reopen the investigation in light of the information and the evidence that’s come out of the four universities and also to put a pause on any dredging operations in the Tees until it’s proven that they’re safe and they’re not going to put any harmful pollutants into the environment."
When silt and sediments build up on river beds over time, dredging is deployed to maintain the water depths of the channels. Dredging vessels regularly scoop up the debris and dispose of it at sea or in landfill.
During the steelmaking years on Teesside, fishermen allege the chemical by-product, pyridine, was disposed of into the River Tees, which then settled beneath the riverbed.
The fishermen claim dredging had scooped this up and resulted in the deaths of thousands of crabs when disposed of at sea.
River conservationist and ecologist, Steve Lowe, said the report findings are a cause for concern when it comes to dredging in other North East rivers.
He said: "The whole premise of the report shows that there needs to be a very active consideration of environmental issues before any of sort of this activity takes place and bearing in mind that most of the North East rivers have had industry on them.
"Quite a lot of them, whether for recreational purposes or for industrial uses, probably will need dredging at some point, then this is a really good red flag to actually, you know, mark our card if you like for making sure we don’t do this again."
A Defra spokesperson said: "A comprehensive investigation last year included extensive testing for chemicals and other pollutants such as pyridine. It concluded a naturally occurring algal bloom was the most likely cause.
"We recognise the concerns in regards to dredging, but we found no evidence to suggest this was a likely cause. There have been no materials licensed for disposal at sea in the area which would fail to meet international standards.
"This is a complex scientific issue, which is why we took a thorough, evidence based approach.
"We welcome research carried out by universities and will continue to work with them, including studying this report carefully. We are aware there have been some localised reductions in catch rates and we are continuing to monitor shellfish populations in the area."
PD Ports, which dredges the River Tees routinely, said: "All dredging and sediment disposal is carried out in compliance with the strict conditions set down by the Marine Management Organisation, and is overseen by our expert team of marine specialists.
"Our standard dredging practice has not changed either in methodology, location or dredging depth for many years."
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