An old whale's tale might not be every scientist's cup of tea but for marine ecologist Adelaide Dedden the secrets locked within the jawlines of humpbacks and southern rights are telling.
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The UNSW PhD candidate believes the lifetime dietary habits of the aquatic giants may correspond with climate change cycles.
Her conviction is based on close-up study of the bristle-like plates that toothless filter-feeding whales rely on to eat, known as baleen.
Each holds a chemical record of the mammal's consumption patterns dating back nearly 60 years, which can indicate changes in their movements and behaviours over time.
Notably, Ms Dedden and her colleagues were able to compare the information to key environmental data.
They found that the same La Nina events contributing to Australia's devastating floods are not good for whales migrating along the country's east coast either.
According to museum samples of baleen, those collected from strandings and previously published data, Pacific Ocean humpbacks exhibit evidence of poorer feeding opportunities during such phases.
With enormous appetites to satisfy and lengthy fasts to endure, the whales become extremely susceptible to changes in ocean-atmospheric cycles, says senior researcher Tracey Rogers.
Humpbacks spend winter breeding in warm tropical waters before returning to southern Antarctica during summer to feed.
During this migration, they're away from reliable food sources and must depend on bodily reserves and opportunistic prey off Australia to survive.
"What is incredible is all of this information about dietary and spatial patterns has been unlocked just through analysing plates in their mouths," Ms Dedden said.
With La Nina events predicted to increase in intensity and frequency, the whales face feeding challenges and there could be increased strandings.
However, the UNSW study found those from Australia's west coast who feed in the Indian Ocean showed increased feeding success during La Nina.
In promising signs, their east coast counterparts also seem to be developing alternative feeding strategies in more temperate waters.
"East coast humpbacks have shown signs of adapting to different feeding strategies in other known productive regions on their migration route ... something future research could look at," Ms Dedden said.
The researchers hope to use their findings to develop models to help predict future whale behaviour which may help with management strategies around whale entanglement and stranding.
Australian Associated Press
