Historical and contemporary population structure and the impact of whaling on sei whales
Maria Jose Perez-Alvarez, Francisca Rodriguez, Sebastian Kraft, Carlos Olavarria, Camilo Naretto, Elie Poulin
International Whaling Commission
The largest whale mass mortality event ever recorded took place recently in Southern Chile, where at least 340 dead rorquals were reported (Häussermann et al. 2017). In this event, all the positively identified whales were sei whales, Balaenoptera borealis. Population studies of sei whale are very limited in the Southern Hemisphere, even though this species was one of the major targets of commercial whaling worldwide, having an important exploitation history, particularly in Chilean waters. In this context, the whale mortality event has become the largest source of samples for the species in the Southern Hemisphere and a unique opportunity to address questions regarding genetic diversity and population structure of the species as well as dynamic of population demography considering historical and contemporary temporal frameworks. We are currently undertaken the analyses of skin and bone samples collected in the area (n = 160). Preliminary analyses of a set of those samples (n = 50) include that (1) the forensic technique we are using has proven successful in amplifying mt and nuDNA (sex), (2) 14 mtDNA control region sequences from skin samples (699 bp) revealed 13 haplotypes (h = 0.989, π = 0.94%), (3) 36 mtDNA control region sequences from bones (650 bp) revealed 23 haplotypes (h = 0.971, π = 0.99%), (4) all sequences corresponded to sei whales when compared with BLAST and DNA Surveillance data bases, and (5) sexing bones samples identified 22 males, 6 females and 8 unknown. Future work will include the collection of more samples from the same area, other areas along Chilean coast where sei whales are observed and other geographic regions in the Southern Hemisphere. We expect to include data from other Northern Hemisphere sei whales through collaboration.