River Otter    Lontra canadensis



Taking a snooze on a Boston Harbor Marina float after a rough morning of play with it's mate, this male River Otter was captured on film by local photographer and yachtsman Jim Anderson.  River otters are occasionally seen around the marina and nearby marine shoreline.  They also occur in a variety of freshwater areas over much of the northern part of North America. 


River otters are large semi-aquatic mammals that are related to weasels and other members of the family Mustelidae.  They are around 26 to 30 inches long with a long (12 - 17 inch) tail and weight between 10 to 25 lbs.  The hair color is mainly brown with white on parts of the head and neck.  The fur is very dense and soft keeping the cold water away from the skin.  Both front and hind feet have claws and are fully webbed.  Their cousin, the sea otter, a resident of the open coast, has a shorter tail, longer body and is heavier, weighing between 30 and 85 lbs. and feeds on it's back while floating on the surface of the water. 


The river otter lives mainly on fish, but will eat crustaceans and other invertebrates and occasionally birds.  They can hold their breath for up to eight minutes during foraging.  They normally hunt at night but can be seen at any time of the day.


Breeding takes place in the spring with two to four pups being born at the same time anywhere from 9 to 13 months after conception (time difference due to delayed implantation of the embryos ensuring mother is in prime condition).  The  young are helpless for the first month and are weaned at three months of age.  They can live up to 21 years in captivity, but normally only 8 to 9 years in the wild.