Vancouver Island Sea Otter Blamed for River Otter Deaths, Researchers Say Behavior Isn’t Unusual

A lone sea otter off the coast of Vancouver Island has become the prime suspect in a series of river otter deaths, according to local wildlife experts.

Mollie Cameron, a whale-watching captain and president of the Wild Wise Society, said she has repeatedly observed the otter, known as Ollie, carrying the lifeless bodies of river otters for multiple days.

"This behavior is not necessarily uncommon, but it has been consistently observed by the whale-watching community over the years," Cameron explained.

She added that the animals she has seen Ollie carrying showed signs of sexual trauma. "He's the only sea otter in the immediate area, so the assumption is that he does this—kills the river otters and then engages in this behavior to release sexual tension," she told CHEK News.

A Known Pattern Among Isolated Male Sea Otters

Sea otters are native to B.C.’s coastline but were nearly wiped out due to the fur trade. Their populations were reintroduced in the 1970s, and a 2020 report from the Department of Fisheries and Oceans estimated that approximately 8,000 sea otters now inhabit B.C. waters.

Vancouver Island University biologist and long-time sea otter researcher Jane Watson said that while this type of behavior may be distressing to witness, it is not unprecedented.

Male sea otters that have not reached social or sexual maturity often struggle to find mates, she explained.

"He's what is sometimes referred to as a satellite male. He’s hoping to establish a territory that attracts females, but it hasn’t happened," Watson said in an interview.

As a result, these frustrated otters may attack and attempt to copulate with other animals, including birds, river otters, and even seal pups. Cameron also recalled reports of a sea otter attacking a dog in a similar manner.

A Mating System That Can Appear Violent

The way sea otters mate is naturally aggressive, Watson explained.

"The male actually grabs the female by the nose during copulation, often leaving them with bloody noses and scars," she said.

However, she cautioned against applying human moral standards to sea otter behavior, emphasizing that this is simply their natural mating system.

To complicate matters, male sea otters are significantly larger than river otters—comparable in size to a German shepherd—which means these encounters are often fatal for the smaller animals.

A Reminder About Wild Animals

While sea otters are often perceived as cute and playful, Cameron warned that they remain wild animals with unpredictable and sometimes aggressive behavior.

"This is an important reminder that while sea otters may seem harmless, they are powerful predators," she said.

For researchers, Ollie’s actions are part of a broader understanding of sea otter behavior, reinforcing the challenges faced by isolated males and the sometimes brutal realities of the natural world.