which dolphin species? | 7 march 2020 | Mikurajima, Japan (1 Viewer)

[HouseCrow]

This fin showed itself briefly alongside the Tokyo - Tokyo Islands ferry, just outside Mikurajima harbour
On a coldish march morning, early march 2020 (last weeks of free travel)
location: 33.894, 139.584

Would you agree that it is Short-beaked Common Dolphin Delphinus delphis?

Harbour Porpoise (Phocoena phocoena)

Harbour Porpoise from Unknown7, Shizuoka, Japan on March 7, 2020 at 05:59 AM by Gerben ter Haar. ID uncertain, fin too short maybe? edit: most likely Harbor Porpoise (after consulting birdfo...

www.inaturalist.org

hope to hear from you
cheers,
G erben

 

[Andy Adcock]

I'm far from expert but it doesn't look like the images of S-f Common that I've seen on Google. The fin looks more like that of a Porpoise to me but wait for others who actually know what they're talking about!

 

[Farnboro John]

It doesn't look like Common Dolphin to me. BTW Common Dolphin was lumped recently and there is no longer a division between Short- and Long-beaked.

John

 

[HouseCrow]

thanks for your replies. I'll have another look at porpoise. I thought these fins were more compact than on this animal...but I am the least expert of the three of us.
I didn't know about the lumping of the two. Inaturalist obviously does not (yet) follow it either. I will bring it to their attention.

No idea what it might be John?

cheers,
Gerben

 

[Farnboro John]

thanks for your replies. I'll have another look at porpoise. I thought these fins were more compact than on this animal...but I am the least expert of the three of us.
I didn't know about the lumping of the two. Inaturalist obviously does not (yet) follow it either. I will bring it to their attention.

No suggestions are coming from you than John?

cheers,
Gerben

Without checking literature no, but I think Andy is probably right. The fin is almost shark-like with no recurvature in the trailing edge such as Common Dolphin would show.

Cheers

John

 

[HouseCrow]

Thanks again, I'll enter it as probable East Pacific Harbour Porpoise then.

cheers,
Gerben

 

[Godly70]

Can't say, as i can't see a clear picture of it .

 

[Mad4Birds]

This does look good for Pacific Harbour Porpoise. The falcate shaped fin is more of a feature than in the nominate Atlantic subspecies and there is some evidence for considering a separate western pacific form, which in turn may have the falcate shape as even more of a feature. Lots of small nicks on the rear edge - ? cause. Interesting photos all round - thanks

 

[HouseCrow]

An observado.org admin suggests (not a definit ID) Fraser's Dolphin (Lagenodelphis hosei). Any chance he might be right?

cheers,
G

 

[Mad4Birds]

An observado.org admin suggests (not a definit ID) Fraser's Dolphin (Lagenodelphis hosei). Any chance he might be right?

cheers,
G

Possibly - you probably couldn't rule it out absolutely just on these shots but a few of things against that particular species - its usually a deep water species found in large groups and, being a dolphin rather than a porpoise, would be more likely to 'show more' eg more dynamic swimming style. But heh, this is nature - walrus in UK this summer and (still) one in Holland.

 

[HouseCrow]

Thanks for that reply Mad,
I don't remember seeing more than just a diving fin like on the photo, I was waiting to see some birds at dawn. It may have been jumping about on the other side of the boat for all I know.
I don't know how deep these waters around these Volcanic islands are. But they are well off shore so...

Is the fin not too hooked in Fraser's?

cheers
G

 

[Mad4Birds]

its not a species I'm familiar with but looking through references the fin can vary in shape, enough for yours to be within that range. If I was doing a formal survey I'd be recording this as 'unidentified small cetacean'😂

 

[HouseCrow]

thanks. I had best rename it then to 'USC' : ) It is how it is of course...
I was hoping for Japanese avid mammalists to reply in inaturalist but no luck sofar.
I have no knowledge of what is common around these islands....birds butter- & dragonflies fine, mammals...no.

cheers,
G