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Sea and river otter have long captivated our hearts with their playful antics and sweet little faces! They are one of Vancouver Island’s most popular attractions, but what if we told you they are not as docile as they seem? Otters are voracious predators of the Salish Sea; they eat around 20% of their body weight every day in invertebrates and small fish. River otters have even been seen drowning Canadian geese and dragging them off shore!

Although sea and river otters might seem like the same species, here are four key ways to tell them apart:

1. Size: You may not believe how big sea otters can actually be! Female sea otters can weigh up to 60 pounds, while males can weight up to 100 pounds. River otters, on the other hand, are much smaller as they can only grow up to 1.4 m long. Females can weigh between 10 and 20 pounds, and males can reach a maximum of 30 pounds.

2. Swimming style: Both otter subtypes love to swim and find food in the sea, but their swimming style is quite different. River otters swim with their belly down, keeping most of their body below the water. They live along coastal shores, typically bring their prey ashore to eat, and they even den on land! Meanwhile, sea otters swim on their backs, live at sea, and rarely come ashore as they are clumsy on land. Sea otters have the adorable habit of floating on their backs when eating their prey, holding their babies, or sleeping while holding hands with each other.

3. Location: The easiest way to tell what kind of otter you are spotting is by examining its environment. Sea otters are mainly found on the northeastern seaboards of the Pacific Ocean. They inhabit the Goose Islands, off the central coast of British Columbia, as well as areas around the northwest coast of Vancouver Island, mainly the area of the Brooks Peninsula. River otters live in freshwater rivers, lakes, and wetlands. They can be found throughout Canada, and in British Columbia, you can spot them in the Georgia Depression and Coast and Mountain ecoprovinces.

4. Motherhood: Sea and river otters have adorable ways to take care of their babies, and one key aspect that distinguishes them is their number of pups. On average, river otters have two to three pups per litter. Female river otters will build dens on riverbanks to keep their young ones safe and will take them down to the water after their fur grows in, which takes about two months. Sea otters, conversely, give birth to only one pup, and they keep them nestled on their stomachs for around eight months until they are old enough to swim. Female sea otters are even known to wrap their babies in kelp to keep them warm while they’re off hunting!

Works consulted and further reading:

How to Tell the Difference Between Sea Otters and River Otters. (2019, January 30). Ocean Conservancy.

Is it a sea otter or a river otter? (2018, May 30).

An introduction to The North American River Otter. (2024, March 31).

Celebrate World Otter Day May 29 with these ‘otterly’ awesome otter facts. (2024, May 27). BC SPCA.

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