Ismaele Tortella / Eurasian otter (Lutra lutra) hunting in a shoal of Atlantic herring (Clupea harengus), northern Norway, March

George Sanker / North American river otter (Lontra canadensis) swimming with head above water. Acadia National Park, Maine, USA. November.

George Sanker / North American river otter (Lontra canadensis) two in water with autumnal trees reflected in the water, Acadia National Park, Maine, USA, October.

George Sanker / North American River Otter (Lontra canadensis) two swimming near the surface with autumn leaves reflected in water, Acadia National Park, Maine, USA, October.

Mark Carwardine / Northern / North American river otter (Lontra canadensis) swimming, Captive, Slimbridge, Gloucestershire, UK, July

Michael Quinton / North American River Otter (Lontra canadensis) on iced over river, Yellowstone National Park, Wyoming

Nick Garbutt / North American river otter (Lutra canadiensis), two standing at edge of frozen Upper Yellowstone River, Hayden Valley, Yellowstone, USA. February.

Matthew Maran / Shelduck (Tadorna tadorna) flying close to the River Otter, Devon, England, UK, June.

Danny Green / North American otter (Lontra canadensis) eating a fish, Yellowstone National Park, USA, February

Jussi Murtosaari / Eurasian otter (Lutra lutra) in winter, Finland, December.

John Cancalosi / Three River otters (Lutra canadensis) rolling, scratching and grooming itself on a log, Wyoming, USA, July.

John Cancalosi / River otter (Lutra canadensis) rolling, scratching and grooming itself on a log, Wyoming, USA, July.