Monday, July 21, 2008

Sei it isn't so!

Recently, I've been in a cetacean frame of mind. My last two trips have had some wonderful whale watching experiences, and I am off in a couple of days to look for Blue Whales in the Santa Barbara Channel northwest of Los Angeles. I really do love the experience of encountering whales in the wild. I've actually been fortunate enough to see a lot of different kinds over the years. But there are a few that have eluded me. Foremost among these is the Sei Whale, an enigmatic species that seems to be pretty elusive. I'm hoping I will just stumble upon one on a pelagic some day, but it doesn't sound like they are very common anywhere. If a hot tip comes along and I can get there...I'm there!

Sei whale is a bit of an enigma anyway. For starters, English speakers can't seem to agree on how to pronounce it, even in print. It is either "say" or "sigh". It also has separate populations in the northern and southern oceans that may represent different species. It is believed to be the fastest of all of the baleen whales, and tends to be an irruptive species, becoming locally common for brief periods in an unpredictable manner. 

On top of everything else, Sei Whale has a close cousin named Bryde's Whale with which it has a long history of being confused.  Now if you think the Sei Whale story is muddled, the Bryde's Whale complex is, well, complex. First of all, it's not "Brides" but rather something like "Broo-dess". But pronouncing its name correctly is just the tip of the iceberg. The holotype specimen was an individual found in Burma in 1878, and given the name Balaenoptera edeni. Another baleen whale taken in 1913 off South Africa was named B. brydei, after a whaler named Johan Bryde, but was later lumped with edeni. Since that time, it has been determined that there are multiple forms of what is known as Bryde's Whale, including a smaller inshore version and a larger pelagic version constituting at least two good species. 

The problem is that no one knows which form the 1878 holotype belongs to. And apparently, no one has been able to get access to it to do the necessary DNA analysis. If it is edeni, then all is right with the world, and the small forms can be called edeni. If it matches the DNA of the larger forms, then they will become edeni, and brydei will become a synonym of edeni, while a new name will need to be chosen for the smaller form. Clear as mud? Good, it gets better!

There is also another form that researchers have tied with Bryde's until recently, namely the uber-enigmatic Omura's Whale, B. omurai. First described in 2003, this form (also named for a whaler) was initially thought to be closely related to Bryde's, and by some perhaps even to be nothing more than an example of the smaller inshore form edeni.  But recent DNA analysis suggests that this is indeed a good species, and not a close cousin to any form of Bryde's Whale at all, but instead one that branched off the baleen whale tree around the time of the Blue Whale, with the Sei, Fin, and Bryde's whales diverging later. 

Incidentally, I have seen Bryde's Whale once off of New Zealand.  Researchers there don't know for sure whether these are smaller inshore or larger offshore types, but the whales measure out to be toward the larger end of the Bryde's spectrum. All of this makes my head spin (heavy sei!). I'll save the muddled mess that is Minke Whale for another post.  The Bryde's Whale image above is from the Hong Kong Dolphin Conservation Society website.  

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