Blue v Fin Whale – opinions?
In my recent trip report on New Zealand’s South Island, I mentioned that I had seen a pair of blue whales on a whale watching trip. A comment on iNaturalist raised a question over the ID suggesting fin whale as more likely largely due to the shape of the dorsal fin. I reached out to the tour company who agreed this was possible. I’d appreciate any third opinions 🙂
Fin Whale (Balaenoptera physalus) on March 17, 2025 at 07:31 AM by wgilson · iNaturalist
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7 Comments
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Pouti
Hello Warren. The individual on the right is indeed a Fin whale (shape, size and angle of the dorsal fin are diagnostic, and the color and aspect of the skin are good clues). As Jon wrote and as we only see the back of the other one, you can’t say for 100% sure it is another Fin whale, but the color and this very close association suggest it is. Do you have any other picture ?
According to current records, Fin whales are rarely seen in New Zealand, but they occur there. For the Blue whales, there is a New Zealand population of the southern pygmy subspecies, and the southern ocean subspecies may be seen there too during southern winter.
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Warren Gilson
Thanks Jon, Willem and Pouti! I’m travelling at the moment without my laptop or camera (what?!!!!) but I’ll certainly look for more photos once I get home. I have three other photos on iNaturalist (see link above) but they not be more definitive- nevertheless I’m thrilled that the fin whale has the majority here and elsewhere!
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Warren Gilson
The mystery deepens. The new photo showing the dorsal fin of the larger whale is more blue -like than fin-like as I suggested above. One thought is that the smaller (offspring?) may be a fin/blue hybrid sticking close to its blue mum. For anyone interested, there is a lot of info online about fin/blue hybridisation, and the preponderance of male fin/female blue matches.
(albeit recorded in the North Atlantic)
https://onlinelibrary.wiley.com/doi/full/10.1111/eva.13091?msockid=3a00ed0a257c64731140e27924f56552
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Jon Hall
The one at the back looks more like a Fin or a Sei to me too. It is possible the other is a Blue of course which might explain the guide’s ‘mistake’ ….