Data from: Genetic variation in blue whales in the eastern Pacific: implication for taxonomy and use of common wintering grounds

Many aspects of blue whale biology are poorly understood. Some of the gaps
in our knowledge, such as those regarding their basic taxonomy and
seasonal movements, directly affect our ability to monitor and manage blue
whale populations. As a step towards filling in some of these gaps,
microsatellite and mtDNA sequence analyses were conducted on blue whale
samples from the Southern Hemisphere, the eastern tropical Pacific (ETP),
and the northeast Pacific. The results indicate that the ETP is
differentially used by blue whales from the northern and southern eastern
Pacific, with the former showing stronger affinity to the region off
Central America known as the Costa Rican Dome, and the latter favoring the
waters of Peru and Ecuador. Although the pattern of genetic variation
throughout the Southern Hemisphere is compatible with the recently
proposed subspecies status of Chilean blue whales, some discrepancies
remain between catch lengths and lengths from aerial photography, and not
all blue whales in Chilean waters can be assumed to be of this type. Also,
the range of the proposed Chilean subspecies, which extends to the
Galapagos region of the ETP, at least seasonally, perhaps should include
the Costa Rican Dome and the eastern North Pacific as well.