Data from: Blue whale population structure along the eastern South Pacific Ocean: evidence of more than one population

Blue whales (Balaenoptera musculus) were among the most intensively
exploited species of whales in the world. As a consequence of this intense
exploitation, blue whale sightings off the coast of Chile were uncommon by
the end of the 20th century. In 2004, a feeding and nursing ground was
reported in southern Chile (SCh). With the aim to investigate the genetic
identity and relationship of these Chilean blue whales to those in other
Southern Hemisphere areas, 60 biopsy samples were collected from blue
whales in SCh between 2003 and 2009. These samples were genotyped at seven
microsatellite loci and the mitochondrial control region was sequenced,
allowing us to identify 52 individuals. To investigate the genetic
identity of this suspected remnant population, we compared these 52
individuals to blue whales from Antarctica (ANT, n = 96), Northern Chile
(NCh, n = 19) and the eastern tropical Pacific (ETP, n = 31). No
significant differentiation in haplotype frequencies (mtDNA) or among
genotypes (nDNA) was found between SCh, NCh and ETP, while significant
differences were found between those three areas and Antarctica for both
the mitochondrial and microsatellite analyses. Our results suggest at
least two breeding population units or subspecies exist, which is also
supported by other lines of evidence such as morphometrics and acoustics.
The lack of differences detected between SCh/NCh/ETP areas supports the
hypothesis that eastern South Pacific blue whales are using the ETP area
as a possible breeding area. Considering the small population sizes
previously reported for the SCh area, additional conservation measures and
monitoring of this population should be developed and prioritized.