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Sunday, July 31, 2016

Loooong back, curved fin

Okay, remember the picture from last night?  Did you have a guess about which species of whale it showed?

I took these pictures of a Fin Whale (Balaenoptera physalus) during a boat trip to Bodega Canyon and Cordell Bank on 30 July 2016.

Here's a close-up view of the head (below).  Note the raised blowhole area (on the left side).

This whale surfaced remarkably close to the boat, which allowed a few nice views of the back and the dorsal fin.

Although I've been on a few trips to Cordell Bank now, this is the first time I've seen Fin Whales there.  I don't know a lot about their status in the Pacific Ocean, but it sounds like they're more common in southern California.  (Seawater temperatures are much cooler this summer compared to the summers of 2014 and 2015 and apparently there's a lot of krill around right now.  Perhaps the Fin Whales have been attracted by an abundance of food?)

Note the very dark coloration.  The dorsal fin rises off the back at a relatively shallow angle and is quite broad at the base.  The fin is falcate (crescent-shaped) and larger than the fin of a Blue Whale.

Apparently, Fin Whales often have small circular markings in the area near the dorsal fin, perhaps from lampreys or cookie-cutter sharks.  If you look closely at the next picture (click on it for larger version), you can see some paler circular markings.

A few fun facts about Fin Whales:
  • They're bigthey're the second largest whale in the world, reaching lengths of about 24 meters (about 78 feet)
  • They're fast — reaching swimming speeds up to ~37 km/h (~22 mph)
  • They're loud — producing low frequency sounds (20-Hz) that can be heard hundreds of kilometers away  

P.S.  Some of the facts above are from Marine Mammals of the World (Second Edition) by Jefferson, Webber, and Pitman (2015).


Ellie said...

Thanks for another great post, Jackie! Do you know-- are there photo-identification databases for fin whales off California? I'm thinking about fluke IDs for humpbacks, and wondering if it's as possible to distinguish and keep track of fin whale individuals..

Jackie Sones said...

Hi, Ellie,

Not sure about photo i.d. work with Fin Whales, but I'll ask the folks at Cascadia Research. I'm guessing someone has worked on it, perhaps based on body markings and dorsal fins?


:) Jackie