Once you’ve seen one killer whale, you’ve seen them all, right?
When killer 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. In fact, 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. We call these populations ecotypes.
There are 10 known ecotypes around the world (although that may change as we learn more). Much like 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. No war. No genocide. 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, transient (or Bigg’s) killer whales likely diverged from other killer whale populations over 700,000 years ago! This is known as cultural divergence.
In the coastal North Pacific, we have three distinct ecotypes. Resident fish eaters who prefer chinook salmon, transients who are marine mammal connoisseurs and offshores who 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 whales.
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 were the ones in the news early this spring when a research expedition found and photographed them off Cape Horn, Chile.
So there you have the killer whale basics. But wait. There’s more. While there are three ecotypes of killer whales found in BC waters, they’re further separated into distinct breeding populations.
Image captured by Valerie Shore for Eagle Wing
The critically endangered southern resident killer whale population—traditionally found in the summer months in the Salish Sea—is made up of only 75 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 speak a completely different “language” than the southern residents and have their own set of cultural traditions, such as communal rubbing on shallow pebble beaches.
Transient killer whales along the BC coast are also separated into two subpopulations—inshore and offshore—and there is some mixing. The inner coast transients—the ones we see most often—number more than 300. The count for outer coast transients, which we don’t know as well, is more than 200.
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 transient cousins!
Image captured by Brendon Bisonnette for Eagle Wing
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 no. 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.
In short, humans are the ones messing up the marine environment in many ways. It’s up to us to change our ways. Not them.
Special thanks to Uko Gorter for use of his illustrations. A picture says a thousand words!