Graham Elliott, Fens area manager for the Royal Society for the Protection of Birds (RSPB), said that although the sighting, which has been posted on YouTube, was not unique, it was somewhat surprising. You occasionally get seals in the River Ouse near St Ives but Ive never known of one here before, he said. The surprising thing was to see it leaving the river and hopping over the bank, entering the gravel pits area. A spokesman for the wildlife charity added that there was no apparent cause for concern but that the organisation was keeping a watchful eye to register whether it is spotted again. It is thought to have swum from Kings Lynn aided by flood water, as the seal is not thought to have been seen in the area before. Mr Elliott said: Its perfectly happy in the lake with plenty of food to sustain it. Its not a threat to any other wildlife and hopefully it will find its way out the same way it came in. If it cant, well then consult with the RSPCA to make a decision on what will happen next. The video was filmed by a 29-year-old man known as Robjn on Sunday, December 30. It shows the seal swimming from the ditch up into a flooded field before attempting to climb different points of the bank. Since the footage was taken, the seal has become a great visitor attraction, Mr Elliott said, but was only seen once in the five days afterwards. If anybody does see it, wed love to hear the news, Mr Elliott said. It was probably just exploring new views.