You can stop calling North Atlantic killer whales type 1 and type 2

A new paper by Dr. Andy Foote just came out; it encourages people to stop calling North Atlantic killer whales “type 1” and “type 2”. These two types were defined by Dr. Foote himself during his PhD research. Let’s find out why we should stop talking about two types in the North Atlantic.

north atlantic killer whales
A male killer whale in Iceland — Credit: Anaïs Remili

How the two types were defined

Based on museum specimens and stranded killer whales Dr. Foote collected, he could notice some morphological differences between the killer whales. His paper published in 2009 thus described two North Atlantic killer whales. He described Type 1 North Atlantic killer whales as generalist feeders consuming fish mostly and sometimes marine mammals like seals. They showed heavy tooth wear associated with fish consumption; we discussed it extensively in a previous post. Type 1 thus included most North Eastern Atlantic killer whales.

Since then, research has documented the prey-switching abilities of some Icelandic and Norwegian killer whales and showed that some individuals feed on seals and fish. These killer whales identified as “mixed-diet” showed higher contaminant concentrations, reflecting a long-term feeding preference for marine mammals. In both populations, researchers also pointed out that future research should focus on the individuals’ diets instead of categorizing them into large feeding types.

Controversial type 2

Dr. Foote then described type 2 North Atlantic killer whales as specialists feeding on marine mammals. The few whales corresponding to this type showed very little tooth wear, reflecting a diet based on marine mammals. Type 2 was determined based on stranded killer whales in the Faroe Islands and Scotland. But for these individuals, the samples were too decomposed or damaged for DNA data to be analyzed.

The main issue with type 2 killer whales came from the small sample size (5 individuals) and how little it was representative of a potential ecotype. Foote recognized this; we simply lack enough data to talk about types yet. He encouraged researchers to collect samples, especially for the isolated populations of killer whales in Greenland and Canada. The goal of these studies would be to understand the ecology of North Atlantic killer whales. Understanding their ecology will better inform conservation agencies and motivate future conservation decisions. In the meantime, Dr. Foote suggested we just drop the “type 1/type 2” classification for now.

The previous killer whale classification — Credit: NOAA

Let’s focus more on the individuals, less on the types

There is a real need to focus on individuals, not just populations when studying the ecology of whales. We are seeing more and more evidence of dietary differences within various killer whale populations worldwide. In the last couple of years, I’ve seen this movement become more powerful in marine mammal research. Focusing on the interindividual differences and not seeing individual whales as part of a large population (or type) unit will help better understand how they interact with our oceans.

What I think of this as a killer whale researcher

As a North Atlantic killer whale researcher, I have been waiting for this paper for years. I believe Dr. Foote was incredibly humble in his opinion piece. It can be hard to revisit some of your previous research and discuss your previous results a decade after they were published. I also believe his previous paper has truly helped us understand North Atlantic killer whales, and has motivated multiple new research initiatives. My PhD research is almost entirely founded on his papers. POur team is finishing a new study that will dive deeper into what Dr. Foote has suggested — looking at the individuals’ feeding preferences rather than the types. So keep your eyes peeled; there is more North Atlantic killer whale knowledge coming soon!


Foote AD. Are “Type 2” killer whales long in the tooth? A critical reflection on the discrete categorization of Northeast Atlantic killer whales. Marine Mammal Science. 2022.

Anaïs is the founder of Whale Scientists. She is a PhD student at McGill University working on killer whale ecology and pollution. You can read more about her here.

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