Otter video 'very good news' for Staffordshire river
"Unexpected" footage of an otter which was filmed by an underwater camera is "very good news" for a river in Staffordshire, the Environment Agency has said.
The camera had been set up by the agency to monitor how successfully a new fish pass was working.
Bryony Devoy, from the agency, said the images were "fantastic" and show "the whole ecosystem is healthy".
The agency is not saying where the film was taken to protect the equipment.
Other footage gathered includes some of a pike using the camera tunnel as an ambush point.
Ms Devoy said: "The presence of a top predator on a river in the Midlands is very good news... when you consider the pressures and challenges that the wildlife in these areas have to face on a daily basis."
The agency said the camera, which is fitted with a motion sensor, allows them to assess fish movements and populations.
Otters are nocturnal and have a territory of up to 40km (25 miles).
Populations are usually estimated by monitoring droppings and footprints.
The UK otter population has been slowly recovering after almost dying out in the 1970s, thanks mainly to environmental improvements and legal protection.