Once you’ve seen one killer whale, you’ve seen them all, right?
When whale watching off Victoria, our guests are often surprised to learn that there are many types of killer whale and that they’re found in every ocean of the world. They’re the most widespread mammal on the planet other than humans!
While they’re all technically the same species—Orcinus orca—they’re all separate populations that don’t breed or associate with one another. Each population has very slight physical differences, as well as its own food preferences, language, social structure and hunting behaviours—essentially its own unique culture.
What are ecotypes?
Just to add more complexity, we arrange the various populations into ecotypes. There are 10 known ecotypes of killer whale around the world, although that may change as we learn more. As in human society, the culture of each ecotype is passed down from older to younger generations. And while different ecotypes can interbreed and produce fertile offspring—whales in captivity sadly proved that—in the wild, they don’t.
Instead, each ecotype seems to have some sort of mutual agreement that even though they may live in the same waters they’re not competing for the same resources, so they just avoid each other. Avoidance. Tolerance. Harmony. Everyone wins.
It’s likely that the different ecotypes evolved in different places—perhaps separated by glaciers, etc.—learning to hunt and eat whatever prey was abundant in their area. Over time, they’ve become so reproductively isolated that the thought of interbreeding probably doesn’t even occur to them.
In BC, Bigg’s (or transient) killer whales likely diverged from other killer whale populations over 700,000 years ago! This is known as cultural divergence.
Killer whale ecotypes around the world
In the coastal North Pacific, we have three distinct ecotypes. Resident fish-eaters who prefer chinook salmon, Bigg’s who are marine mammal connoisseurs, and offshores who appear to have a fondness for sharks.
It’s a similar story in the North Atlantic: Type 1 eastern North Atlantic prefer herring or mackerel, and Type 2 eastern North Atlantic specialize in marine mammals, mostly other whales and dolphins.
In the southern hemisphere around Antarctica, there are at least five different ecotypes of killer whale.
Antarctic Type A killer whales tend to stay away from the ice and feed mostly on minke whales. Type B have recently been split into two groups: pack ice killer whales which snack on seals around the outer pack ice; and smaller Gerlache killer whales which are penguin specialists.
Type C or Ross Sea killer whales are piscivores, feeding mainly on fish and following channels or openings in the pack ice. Types B and C have a distinctive yellowish colour from diatoms on their skin, as well as a prominent dorsal “cape.” Type C is the smallest known killer whale ecotype.
Last but not least is the Type D or subantarctic Killer Whale, which with its tiny eyepatch and distinct shape, has been seen only a few times. They made the news in 2019 when a research expedition found and photographed them off Cape Horn, Chile.
Distinct populations off BC
So there you have the basics on types of killer whale. But wait. There’s more. While there are three ecotypes of killer whales found in BC waters, we separate them further into distinct breeding populations.
- The fish-eating and critically endangered southern resident killer whales—traditionally found in the summer months in the Salish Sea—number only 73 animals. Yup, that’s the entire gene pool for that population. If we lose them, the world loses that unique and beloved culture of killer whales forever.
- The northern resident killer whales, also fish-eaters, are found mainly off northern Vancouver Island and the north coast of BC. They’re a much larger population with more than 300 animals. They don’t mingle with the southern residents. They speak a completely different “language” and have their own set of cultural traditions, such as communal rubbing on shallow pebble beaches.
- Mammal-eating Bigg’s killer whales along the BC coast are separated into two subpopulations—inner coast and outer coast—and there is some mixing. The inner coast Bigg’s—the ones we see most often—number over 380. The count for outer coast Bigg’s, which we don’t know as much about, is at least 200. There may be yet another population of mammal-eating killer whale that lives far out in the open ocean off the North American coast. Published records of this possible oceanic population go back decades.
- Offshore killer whales are the least-known population because they’re not encountered very often. That’s because they live—you guessed it, offshore. The estimate for that population is about 300 animals. Their language is very different from residents or transients, they tend to travel in large groups, and they too have their own behavioural traditions. One endearing one is that they love to tail-lob, far more than their resident and Bigg’s cousins!
It’s all about culture
So you see, conservation is not just about whether or not two animals can breed together to produce offspring. It’s about ensuring the continuity of a culture, a language, a way of life… much as it is with different human populations.
We often get asked whether the southern residents, as they continue to decline, could switch to become mammal-eaters like transients. Or whether they might eventually interbreed with the northern residents. The answer is to both is not likely. Those ingrained cultural traditions—which have served them well over millennia—are formidable barriers to radical behavioural changes like that. They simply don’t recognize other prey as food or other ecotypes as mating prospects.
Special thanks to Uko Gorter for use of his illustrations. A picture says a thousand words!
First published in April 2019. Updated October 2021.