Blue whales: the ‘true’ and ‘pygmy’ varieties are both found in Chilean waters

The subspecific taxonomy of the blue whale (Balaenoptera musculus) is yet to be fully understood. The suggestion that there was more than one subspecies of blue whale  was originally  put forward as early as 1966 due to a number of morphological differences between populations, most notably the tadpole shaped body of some populations. While the name may not necessarily be appropriate, the name ‘pygmy’ blue whale (B. m. brevicauda) has been given to one such subspecies, previously thought to reside solely within the Indian Ocean though this would be due to lack of classification beforehand. The pygmy blue whale grows to approximately 24 meters long, considerably shorter than the ‘true’ blue whale (B. m. intermedia , 33 meters), and the North Atlantic/North Pacific variety which are currently considered to be of the same subspecies (B. m. musculus, 27 m). Research conducted in 2007 by LeDuc et al. had already shown the difference between the populations off of Australia and South America but had failed to identify any genetic markers and so is impossible to perfectly classify a species as a ‘pygmy’ or ‘true’ blue whale (or even as another subspecies entirely). This study has now been emulated by researchers from the Wildlife Conservation Society, the Blue Whale Center, the American Museum of Natural History, NOAA and the Universidad Austral de Chile into the populations existing in the waters off of Southern Chile, off of Antarctica and the surrounding regions. The study, which was published within the Journal of Molecular Ecology online edition, involved the use of non-lethal biopsy darts to collect skin samples. This led to the identification of 52 individuals using regions of nuclear DNA and mitochondrial DNA and the DNA was compared to datasets from the the Eastern tropical Pacific Ocean, Northern coastal Chile and Antarctica. This led to the theory that there are two distinct subspecies of blue whale sharing these waters, something which was not known to happen prior to this study.

Mike Johnson,

Mike Johnson,

The correct identification of species leads to proper conservation and strategies – giving us a true insight into how badly or well a species is faring and whether there is competition between the species for resources. When questioned, Rosenbaum stated that “Our study gives us crucial insights into the population structure of blue whales in the waters of Chile and will serve as an important stepping stone for further research… The long-term goal of such work would be a network of marine protected areas designed to save the world’s largest animal.”

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Siân Powell
When I started writing on this site my 'info' included that I wanted to study wildlife disease of molecular ecology. I can now say that I will be starting my PhD in September 2015 incorporating both of those areas to examine environmental reservoirs of bovine TB. So I suppose, to write my next goal, I want to write good papers, become a voice for wildlife and (hopefully) become a lecturer who excites their students.

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1 Response

  1. Avatar Herman Human says:

    That photo is of a humpback whale…

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