Scientists have uncovered genetic information about different populations of the Antarctic blue whale (Balaenoptera musculus ssp. intermedia) that could be crucial for conservation efforts to save the critically endangered species.
A team of Australian marine biologists used biopsy samples from past studies on the world’s largest animal to build a genetic dataset of 142 individuals. This data revealed that there are three genetically distinct populations, according to the study published today in Scientific Reports.
“We were able to find evidence of three populations of Antarctic blue whales that had not previously been found,” lead researcher Dr Catherine Attard, an expert in molecular and cetacean ecology from Flinders University, told SBS Science.
“What we found was three clusters of individuals – so within those clusters, individuals were genetically similar, but between the clusters they were genetically different, so these are likely three different populations of Antarctic blue whales.”
A giant of the ocean
The Antarctic blue whale, which is a subspecies of the blue whale (Balaenoptera musculus), had a population of around 239,000 at the start of the 20th century, however whaling caused their numbers plummet to around 400 individuals in 1972 from illegal Soviet whaling before rebounding to around 2,000 in 2012.
The whale has been listed as ‘critically endangered’ by the International Union for Conservation of Nature of Natural Resources since 2008.
This whale subspecies gets its name from spending the Antarctic summer in the frigid waters to feed on massive amounts of krill. Individuals can weigh around 160 tonnes and can grow as long as 30 metres from head to tail.
Attard believes that during the breeding season, each population migrates to a different ocean basin, and previous studies that used acoustic data of Antarctic blue whale vocalisations have located these animals in the south Pacific, south Atlantic, and the Indian ocean.
A key finding in the study was that instead of occupying discreet areas when feeding in the Antarctic, as observed in other species such as the humpback, Antarctic blue whales occupy the same waters, which means conservation efforts need to be tailored for the specific populations rather than the subspecies as a whole.
“If you try to conserve them on a population level, you can’t really do it well in the Antarctic,” says Attard. “What we think is the best way to go… is to find out where they are migrating to, an thereby you can conserve them at their breeding grounds to make sure they don’t become locally extinct.”
Research collaborator Associate Professor Luciana Möller says their study has “provided a piece of the population puzzle, but we still have far to go before we can properly monitor and conserve these populations.”
The next step in the research, according to Attard, will be to use satellite tagging to track the animals in both Antarctic waters and to their specific breeding waters.
“We think this is just the tip of the iceberg,” says Attard. “We need to be able to conserve them all along where they occur to make sure they’re recovering in numbers. The next step would be to continue satellite tagging in the Antarctic.”