Otters have been starring in their own version of Big Brother after secret cameras were placed on Helston's Penrose Estate.

The National Trust hoped that footage captured will prove that the otter population is starting to make a return to the area.

Otters have been in decline in Cornwall since the 1960s and 70s, when their habitats became threatened by poorly kept and polluted waterways.

Loe Pool between Helston and Porthleven was no exception, historically suffering from eutrophication - excessive richness of nutrients often due to run-off of fertilisers from the land, which causes overly dense plant growth - and algal blooms during the summer months. Surveys carried out in 1977 and in 1986 showed no signs of otters and they were thought to have died out in the area.

Over the last 20 years the team at Penrose have seen a dramatic improvement in water quality, largely thanks to the work of the Loe Pool Forum, a partnership of organisations founded in 1996 and headed up by the National Trust. Today there are no longer toxic algal blooms in the summer months, resulting in healthier fish stocks and amphibian populations which provide an ample food source for otters.

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Justin Whitehouse, lead ranger for the area said: "Otters have been spotted by the team of staff, volunteers and visitors sporadically over the past 20 years. In 2016 we decided to find out more about these enigmatic nocturnal residents and invest in a wildlife camera, thanks to funding from Banrock Station.

"After leaving it in place for two weeks we couldn’t believe our eyes when were treated to glimpses of an otter. The camera has been up and running for several months now and we’ve had several visits from the same otter, who we believe to be a male.

"This is a great result from all the work the group have been doing, and is at the heart of what the National Trust stands for. It’s amazing to see how our nature-first approach is working to make this area a healthy place for wildlife once again."

Last autumn the team, with the help of local volunteers, built a man-made otter holt out of logs and brash for breeding.

Volunteers are continuing to help manage the wet woodland habitat, in the hope the otters continue to thrive.