The War of the Salish Sea

The waters off the east coast of Vancouver Island are getting busier with the recent arrival of large numbers of marine mammals, especially humpback whales, white sided dolphins and pods of transient orca or killer whales.

The bullies of the Salish Sea are the transient killer whales that, as the name suggest, eat dolphins and sometimes whales too. We're far more familiar with pods of resident orca that are fish-eaters.

Whale watching tours have become a big business of late with the ever larger populations of marine mammals. Earlier this week they witnessed an attack by transient orcas on humpback whales in the waters near Victoria.

Tour operators said the two adult humpbacks were keeping the orca away from their vulnerable calf when the cavalry showed up in the form of several other adult humpbacks who joined forces to drive the attackers off.

It's believed that the arrival of these new top predators is the result of their prey fish, herring and sardines, migrating north from ever warming waters off the US west coast.

Here's a video of transient orca at work in the waters off Vancouver Island:



It's still rare to witness an orca attack on great whales. Far more common are attacks on another newcomer, large pods of common and white sided dolphins.
The orca herd the dolphins into bays and then have at them. One spot they use is at the BC Ferries terminal at Departure Bay, Nanaimo.



Update:

Researchers observing the Humpback whale intervention have found the big whales will come to the rescue of just about any sort of marine mammal under attack by the orca. It's thought they have an instinctive reaction to drive off the killer whales. They've even been known to swim to the rescue of seals and sea lions.