Stunned beachgoers have described their horror after finding “thousands” of dead sea creatures washed up along a six-mile stretch of coastline. Shocking footage, filmed on Saltburn beach, North Yorks., shows rotting razor clams, starfish and other crustaceans spread across the normally sandy shoreline. And further down the coast, on Hartlepool North Sands beach, locals filmed mounds of dead kelp, usually carpeting the ocean floor, piled up beneath sea barriers. A spokesperson for the Department for Environment, Food and Rural Affairs (DEFRA) said “storm conditions” were responsible for the incident. But local activists have claimed dredging work at the mouth of the River Tees - needed to create the UK’s largest freeport - has led to a “mass die-off” of sea life. Jamie Widdowfield, 34, who skippers three fishing boats out of Hartlepool harbour, said he’d “never seen it this bad” and raised concerns about the impact on his industry. He said: “I came across it about 9am this morning after I dropped my kids to school. I spotted it as I was walking along the boardwalk with my father. “I have never seen it this bad. I’ve been a fisherman since I was 15, and I’m now 34, and I’ve fished all the water in this area. “Each year we get something similar washing up. But this is 95 per cent more than what we normally get, at least.” The incident comes after another similar event in September and October last year when tonnes of dead crustaceans washed up along the shoreline. This coincided with initial dredging work for the construction of the new South Bank Quay, sitting on the river Tees, which is set to become the UK’s largest Freeport. The government claims these ports, which have unique economic regulations, will create thousands of jobs for local people, particularly in deprived areas. But Jamie, a dad of three, said his business had been severely impacted after the work began, with his lobster catches dropping from roughly 100 a day to “nothing”. He said: “We were previously getting 100 lobsters a day, but then we got nothing. We blame the dredging for that situation. “The kelp sits on the sea bed, and it absorbs carbon dioxide. I’m not a marine biologist, but it seems like it’s something to do with the ecosystem, something’s not right. “It affects our way of life. My other two brothers had to get jobs onshore, and now it’s just my father fishing at the moment.” Further down the coast, at Saltburn beach, keen surfer and dogwalker Jemima Stubbs, 37, said she came across tonnes of dead shellfish yesterday (Wednesday). She said: “I was walking down to go surfing and I could see it from the top. It’s happening quite frequently now. “I was walking through dead sea life, they were crunching under my feet. It’s so heartbreaking. “There were all sorts of crustaceans: starfish, muscles and different shells. It’s become more and more frequent since the big die-off last year.” This year, DEFRA ruled out dredging in the mouth of the River Tees as responsible for marine life deaths, after the government launched a high-priority investigation. But mum Jemima says she believed the inquiry was flawed. She said: “If you read their report, it’s so flawed – completely flawed all of it. There’s a lot of public attention now, and a lot of distress. “We’re surfers and we live here. We see all the big swells. It’s not unusual for us to get big waves. But it’s very unusual to get dead crustaceans because of it. A spokesperson from Defra group said the dead sea life was caused by a “naturally occurring algal bloom”. They said: “Environment Agency officers are attending reports of seaweed and deceased marine life being washed up on beaches on the North East coast. “This is a regular occurrence at this time of year and follows stormy conditions over the weekend which can often have a significant impact on the marine environment. “We are mindful of the high number of shellfish washed up last winter and continue to monitor stocks closely. “A comprehensive investigation was conducted earlier this year, concluding a naturally occurring algal bloom was the most likely cause.”