Otter species on the Pacific coast of Canada - a comparison

Sea otters (central) and river otters (insets) of the Pacific coast in Canada

There are 13 species of otter in the world, two of them in all of North America.  The North American river otter lives throughout most of Canada and Alaska, while sea otters live exclusively along the Pacific West Coast of America, along the Aleutians, and along the coastline of Japan and its islands.  

Sea otters are very uncomfortable on land as their large flipper-like feet are positioned and made for swimming.  They spend by far most of their time in the water, coming out rarely to avoid predators or storms.  The interesting thing is that sea otters may wrap themselves in anchored kelp to keep from being tossed about by the waves.  Sea otters sleep in the ocean by floating on their backs and may form groups called rafts that are kept together by hand-holding.

River otters (which is what we will call the North American river otter from now on) prefer fresh water but are well adapted to salt and brackish water.  They are very comfortable on land and will often haul out of the water to eat whatever morsel they have caught.  They sleep on dry land and live in burrows along river banks or in old beaver lodges; in the winter, they are active and enter the water to hunt through tunnels or ice holes.  They often bask in the sun.

Both species are carnivorous, although their diets vary significantly.  River otters are primarily piscivores (fish eaters) but will also take crayfish, insects, and any other small organism that they can catch.  Their diet is more varied in marine and brackish environments.  Sea otters, being strictly marine, eat marine shell-encrusted creatures such as shellfish, crabs, and shelled mollusks.  River otters, with their agile maneuvers and strong tails, will catch fish and prey attempting to escape from their grasp.  Sea otters take food off the marine bottom and bring it to the surface, often using a favourite rock placed upon their chest to crack the shell.  They use their strong front paws to repeatedly hit their prey against the rock until they successfully overcome the hard external protection.

River otters have one to six kits once a year, which are born on land, usually in a den, and are helpless until after about two months.  Sea otters are born in the water and are equally helpless, but are very buoyant because of their fur.  They start to dive after about two months of age.

It's interesting how these two species of otter are so different from each other.  The photos above are mine, the latest ones being the sea otter photo I took this fall while visiting Alaska.  I also saw sea otters along the West Coast Trail and in Victoria.  I have seen river otters in many freshwater systems, both here in BC and in Alberta.

Thanks for reading.

Eric Svendsen     www.ericspix.com