DEFRA has uncovered the cause of dead crabs and lobsters found washed up on the North East last year.

The investigation by Defra and partner agencies found that the deaths of tens of thousands of crabs and lobsters potentially resulted from a naturally occurring harmful algal bloom.

A spokesperson for Defra 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."

Fishermen feared for their jobs as they alleged that these deaths may be linked to the dredging of the River Tees. But, a review of dredging activity and water samples found no evidence of a link between the disposal of dredged sediment and the deaths.

"The sampling of sediment that has been licensed by the MMO for disposal to the designated sites off the Tees confirmed that no chemical determinants exceeded concentrations that would be harmful to marine life," the spokesperson added.

The investigation also found no evidence of a food safety risk from healthy fish and crustacea, including crabs and lobsters caught off the North East coast.