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Thursday, September 10, 2015

Common again


Four Short-beaked Common Dolphins (Delphinus delphis) along side the New Sea Angler near Cordell Bank.
 
During most years Pacific White-sided Dolphins
(Lagenorhynchos obliquidens) would be more common than Common Dolphins...but as on last year's trip in early September, on 9 September 2015 we only observed Short-beaked Common Dolphins.
I didn't get great pictures this year, but it seems worth documenting the presence of Short-beaked Common Dolphins in this area.  They didn't stay near the boat for long, but we estimated there were ~30 individuals (or so).

Note the prominent beak, the uniformly gray dorsal fin and the cream color along the side. Pacific White-sided Dolphins have a shorter beak,  much more white on their dorsal fin, and patches of gray and white on their sides.  To compare, review the post from 3 September 2012.


One more picture:


Although the offshore water temperature on 9 September was ~54°F (~12°C), this summer it has reached ~64°F (~17°C).  Short-beaked Common Dolphins have a more southerly distribution, so perhaps this year's developing El Niño or last year's lingering "blob" of warm water has drawn them north again or encouraged them to stay.

P.S.  Click here for Short-beaked Common Dolphin photos from 2014.  

CORRIGENDUM (19 September 2015): After seeing more common dolphins on 18 September, I'm now leaning towards calling the dolphins in the photos above Long-beaked Common Dolphins.  I wish the pictures were better, but for now I'm at least making sure you know that I have questions about the identity of the dolphins above based on what can be seen in these pictures.

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