Flinders University has conducted an extensive study on the current status of global blue whale populations. 

The blue whale, Balaenoptera musculus, is the largest living animal, with an average length of 27 metres. 

Historically, these creatures have faced near extinction due to whaling. However, recent studies indicate a gradual recovery, albeit now facing the new challenges of global warming, pollution, shipping, and other human-induced threats.

The research presents a detailed stocktake of blue whale populations, focusing on their number, distribution, and genetic diversity. 

Dr Catherine Attard, the study's first author, highlights the significance of conserving each group to maintain species biodiversity.

“Each of these groups needs to be conserved to maintain biodiversity in the species, and there are indications that natural selection in different environments contributed to driving genetic differences between the high-level groups,” Dr Attard says.

Significantly, the study found no evidence of inbreeding among blue whale populations, which is encouraging for the species' potential recovery. 

However, the endangered species continues to face numerous challenges, including underwater noise pollution, environmental contaminants, and the changing availability of food due to human impacts on ocean productivity.

“Our findings build on decades of work to improve the management of endangered blue whales under the International Whaling Commission,” Dr Attard said. 

The study estimated migration rates between 1 to 4 per cent among the high-level groups, suggesting both migrant individuals and hybrids among these groups.

An unexpected finding from the research was the genetic similarity between the eastern South Pacific and eastern North Pacific blue whales, challenging the current classification of these populations as separate subspecies. 

Researchers have expressed surprise over this discovery, given the traditional belief that blue whale populations have opposite breeding seasons across the equator.

The study also identified areas in the Indo-western Pacific with distinct blue whale populations, emphasising the need for whole-genome population studies to better understand adaptations in blue whales and other baleen whales. 

The researchers call on the International Whaling Commission to refine stock delineations for blue whale conservation and management, urging national bodies to minimise human activities that could impact these groups. 

The full study is accessible here.