The Varberg Fortress moat monster?

Varberg Fortress was built in 1287-1300 by Count Nielsen as protection against a Danish king, who had declared him an outlaw. Varberg is a coastal town south of Gothenburg in Sweden . The fortress has a moat said to be inhabited by a small lake monster. In August 2006 two witnesses claim to have seen a creature emerge from the dark water and devour a duck. The creature is described as brown, fur less and with a 40 cm (about 15- 16 inches) long tail. Other witnesses also reported seeing something.The sightings made headlines in local newspapers and media. The moat is apparently connected with the sea.. The reports were then taken up by the country wide media and lots of people turned up to investigate what was in the moat. The water is murky so visibility is limited. One investigator tried to listen with microphones and divers tried to look for the creature. Nothing conclusive was found but some thought it could have been a seal, a big pike or a big catfish (Silurus glanis) that somehow got into to moat. It may have been placed there or got in by itself through the access to the sea.

I have been unable to find any more reports but it sounds like a seal and large pike are not unknown to take wildfowl if they get the chance. So the probability is a natural explanation and not an unknown creature. If anyone has any information about recent sightings or more information please post a comment.