Polaris, Dipper and the Death of the Southern Resident Killer Whales: Part 2: Killer Whale Culture

Polaris, Dipper and the Death of the Southern Resident Killer Whales 
Part 2: Killer Whale Culture

Guest Blogger: Courtney Halvorson

Around the world, in every corner of the oceans, there are killer whales. They are the most widespread of mammals and depending on the geographic location and food source, they have differentiated populations based around culture. Each culture has a unique language, differing group size and hunting techniques depending on location and prey source. They become specialized on a particular prey and hunting techniques are passed down from generation to generation by the matriarch (matriarch is the female head of a family vs patriarch for a male).

We call these different populations “eco-types” and in our part of the world, the most researched and identifiable ecotype is the Southern Resident salmon fishing killer whales. These whales have a diet which consists of approximately 80% Chinook salmon. Chinook salmon are the largest and fattiest of the Pacific salmon 

species, but are also the least abundant due to overfishing, habitat degradation and changes in ocean conditions.

Each Southern Resident Killer Whale has been photographed, identified, alpha-numerically named and given a common name, making identifying these whales

an easy task for whale watchers and researchers. The dorsal fin, or fin on the back, has a unique shape and the saddle patch which is right behind the dorsal fin is distinctive for each individual. No two whales are identical. Our whale population consists of 80 individuals in 3 pods – J, K and L. Each pod is made up of related whales or family groups that travel together. When you are born into a pod, you will stay with your mother for your entire life. As scientists, we can tell these pods apart visually but also acoustically as all 80 whales speak the same “language” but each pod has a specific dialect or accent. This means they understand each other and communicate, but this difference reduces inbreeding within a pod. Females will choose a male from another pod with a different dialect. After spending time with these family groups watching them socialize, talk to each other and care for one another you can’t help but create relationships with these animals. They become your second family.

The main benefit of a specialized prey source is that competition is reduced between species. This is especially true since the Southern Residents share the inland waters of the Salish Sea with another ecotype – Transient (Bigg’s) or mammal eating killer whales. These two eco-types rarely interact, and do not mate. Much of this separation has to do with the fact that they eat different foods and speak different languages.

The major disadvantage of a specialized diet is that you become extremely vulnerable if your food source is scarce. If the Southern Residents experience food scarcity, the whales will spend more time foraging and travel overgreater distances. The whales are much more spread out during foraging behavior, meaning they are having to work harder to find individual fish. This reduces time spent socializing and the result – less reproductive behavior in an already critically endangered population.

Check out part one and stay tuned for developments as we release this six-part series throughout the week. 

Courtney Halvorson is a PNW educated Marine Biologist, Wildlife Photographer and Marine Naturalist for Orca Spirit Adventures in Victoria, British Columbia.

Orca photo credit: Duane Fuerter