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Sunday, July 27, 2025

Swimming north rapidly

  

This was a little unexpected, but as I was watching the Humpback Whales yesterday (26 July 2025), I caught a glimpse of a fin much closer to shore and realized it was a Bottlenose Dolphin (Tursiops truncatus).

I wasn't quite ready and didn't get a great photo, but I thought one photo was possibly good enough to identify the individual.  So I sent it off to Bill Keener at The Marine Mammal Center.  Sure enough, Bill was able to match this to a known female in their catalog.  "Cepat" has been seen in Sonoma County before, and as far north as Sea Ranch. 

Here's a few of her heading north:

 
By the way, Bill mentioned that Cepat doesn't usually travel alone, so it's a good time to keep an eye out for other Bottlenose Dolphins in the Bodega Bay area.  Let us know if you see any!  

P.S.  I was curious about the name "Cepat," so I looked it up.  Sounds like it's an Indonesian word meaning rapid, quick, or swift.

P.P.S.  Many thanks to Bill for providing the background information about Cepat and for monitoring local marine mammals!

ADDENDUM (31 July 2025): Some people have inquired about how Bill identified Cepat.  Individual Bottlenose Dolphins have distinctive markings on or near their dorsal fins.  So if you get a good enough photo and the dolphin is a known individual in the photo catalog, you can match the markings.  Here's a close-up where you can see a couple of distinctive notches at the base of Cepat's fin:

 

2 comments:

Limantour walker said...

I'd be really interested to know how he identified her! Is she tagged (with an ID?) so they can track her? Is there a tell-tale mark on her back/fin?

Jackie Sones said...

Yes! Bottlenose Dolphins have distinctive markings on/around their dorsal fins that are stable over time so they can be used to identify individuals. Cepat has a couple of distinctive notches at the base of the fin (visible when zoomed in). Maybe I can add a close-up photo so you can see the notches, too.

:) Jackie