The Pacific Northwest is home to an array of amazing and wonderful animals. Southern Resident and transient orcas and California Gray Whales frequent many parts of the Salish Sea and the waters off the coast; the largest unmanaged Roosevelt Elk herd is found in the Olympic National Park (specifically the Hoh Rainforest); tufted puffins, barn owls, and bald eagles are just some of the birds that live in different ecosystems around the northwest.
In addition to all those animals and the many others that live here, there are otters that also call this place home! River and sea otters come from the same family but they’re unique and different in their own ways!
The North American River Otter is actually the only river otter found north of Mexico and spends most of its time in bodies of fresh water (i.e. streams, lakes, wetlands) along marine coasts in the United States and Canada, including parts of the Pacific Northwest. These otters have all webbed feet that allow them to be active, playful swimmers!
- Rescued sea otter pup finds new home at Oregon Zoo by Kale Williams, OregonLive
These otters are opportunist eaters but primarily eat fish like carp and mud minnows, freshwater mussels, amphibians, bird/fish eggs, birds (usually injured ducks or geese), and more. They’ve also been known to take advantage of nearby salmon runs! Unlike sea otters (their similar but seagoing cousins), river otters spend time in fresh, brackish, or saltwater and have been known to travel on land for significant distances.
Found along the coastal areas of the North Pacific Ocean and ranging from the shores of Japan to Alaskan coast and along the North American coast down to Baja, California, sea otters are an incredibly important keystone species. They help to define their ecosystem and maintain the environment through their diet (and keeping some invertebrate populations down).
Despite the fact that these otters spend most of their life in the north Pacific Ocean, they actually don’t have any blubber to help them keep warm. Instead, their dense fur coat and diet help! These otters typically eat 20-25% of their body weight every day to keep their temperature up and will eat clams, mussels, crabs, fish, and so much more. While they’re usually meticulously clean, sea otters are actually very messy eaters. They’re so messy that some hungry harlequin ducks have been spotted following them around to pick up any dropped food!
Sea otters have and continue to face threats to their survival. Their pelts were highly prized and wide-scale hunting in the 18th and 19th centuries reduced the worldwide sea otter population from 300,000 to around 2,000. Sea otters along the California coast were hit particularly hard during this time, with that population dropping from around 15,000 to just 50. While sea otters are now protected and their population has grown, they still face issues of diseases, major oil spills, habitat degradation, and conflicts with humans.
These otters might be close cousins but there are actually a number of differences between river and sea otters. Their habitats are a big difference, as sea otters primarily live in the ocean or sea and are rarely seen on land. River otters, on the other hand, will often be on land with a loping gait and can be found in fresh or salt water. Sea otters will also be a bit awkward on land while river otters can be swift and agile on land. Their feet are also a major difference, as river otters have entirely webbed feet and sea otters have webbed front feet and rear flippers.
While both otters generally tend to be the same length as adults, sea otters weigh significantly more at around 40-80 pounds. River otters, on the other hand, often weight 11-30 pounds. In addition to the weight difference, the coats on sea and rivers otters differ, as sea otters have a dense coat while river otters have short, coarse fur with two layers. The coloring also differs slightly between the two.
Other differences include reproduction, social needs, and family groups. Sea otters tend to only have one pup in a litter and live in large colonies while river otters will have 2-3 pups and tend to be less social. And while both are great swimmers, the way they swim differs too!
River and sea otters are both amazing and wonderful types of otters that call parts of the northwest home. They may have their differences but they do have some things in common: they’re incredibly cute and vital animals of the Pacific Northwest!