Resumen:
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.