Little evidence for interchange between north-east Pacific and southeast Pacific blue whale populations despite morphological similarities
Trevor A. Branch
Population structure and relationships are examined here between blue whales in the north-east Pacific Ocean (NEPO) and south-east Pacific Ocean (SEPO). The two populations have similar total lengths, lengths of sexually mature females, and tail length as a proportion of total length, and these features distinguish them from the western and central North Pacific, Antarctic, and pygmy blue whale populations. However, available data from catches, sightings, surveys, satellite tags, acoustics, and genetics all provide strong and coherent evidence for a division between the two populations at 2°N to 6°N, albeit with rare vagrants that may briefly move from one region into the other.