Project 0809/13

Project Title: Unravelling the genetic structure and diversity of Balaenoptera musculus in Australia: the genetic identity of Geographe Bay blue whales

Chief Investigator: Dr Luciana MÖller

The Activity involved further elucidating the genetic structure and diversity of Australian blue whales by filling the gap in genetic assessment of Geographe Bay whales and performing a powerful investigation of Australian blue whale population genetics using 10 microsatellite loci and a 394 bp fragment of the mtDNA control region. The significant findings of the Activity are that Geographe Bay blue whales cannot be excluded from belonging to the Australian feeding aggregations genetic population and that the two known Australian feeding aggregations constitute one genetic population.

Genetic assessment of Geographe Bay blue whales
A large component of the Activity involved biopsy sampling Geographe Bay blue whales, which had never before been sampled. Seven individuals were successfully biopsied, 6 were laterally photo-ID on both right and left sides, and 6 on only one side. The paucity of individuals biopsied relative to the aim of 30 individuals is likely due to a less than usual level of blue whale numbers this season compared to previous seasons, and the peak of the season potentially occurring earlier than usual. Genetic analyses of Geographe Bay blue whales was conducted but must be considered in light of the paucity of samples.

The microsatellite data had no evidence for null alleles, stutter bands or short allele dominance, and there were no significant deviations from Hardy-Weinberg equilibrium or evidence of linkage disequilibrium. None of the individuals had been resampled at any of the Australian feeding aggregations (up to 2008/09 season). The microsatellite variation (average 4.20 alleles per locus (SD 1.14), mean observed heterozygosity 0.602 (SD 0.040), mean expected heterozygosity 0.640 (SD 0.040), allelic richness 4.04) and mtDNA control region variation (haplotype diversity 0.714 (SD 0.181), nucleotide diversity 0.003 (SD 0.002)) is comparable to our findings for the Australian feeding aggregations (see manuscript attached to progress report).

Power analysis indicated that a microsatellite FST   0.040 could be detected with  95% confidence (96.2% Fisher’s exact test, 99.0% chi-square). Fixation indices based on microsatellite loci (FST = -0.013, P = 0.491) and mitochondrial haplotypes (FST = -0.057, P = 0.996) show no significant evidence of genetic differentiation between Geographe Bay and the feeding aggregations. Also, the 4 sequenced mtDNA control region Geographe Bay haplotypes are all shared with the Australian feeding aggregations. Due to the paucity of samples, an assignment test was conducted which indicated that none of the Geographe Bay individuals could be excluded from the Australian feeding aggregations genetic population (P > 0.05). Additional analyses will be carried out when we receive the IWC Antarctic samples (we have been granted access by the IWC Scientific Committee). The samples collected from Geographe Bay as part of this Activity have greatly contributed towards determining the genetic identity of these blue whales, and AMMC 09/10 funding to MÖller et al. (Population size of blue whales in Australian waters) will provide further samples that will allow more powerful analyses.

Powerful genetic analysis of Australian feeding aggregations
The Activity also involved biopsy sampling in one of the Australian feeding aggregations, the Bonney Upwelling (VIC/SA), due to the paucity of samples at this aggregation that has previously limited genetic analyses. Ten individuals were successfully biopsied during the main research period, plus an additional whale by Gill. These samples have substantially added to the resubmitted manuscript entitled “Genetic diversity and structure of blue whales (Balaenoptera musculus) in Australian feeding aggregations” (see manuscript attached to progress report). The increased number of good quality samples (from 14 to 25) and an increase in the number of microsatellite loci (from 6 to 10) has allowed more powerful genetic analyses which has confirmed that the two known Australian feeding aggregations of blue whales, the Bonney Upwelling and the Perth Canyon (WA), constitute one genetic population.