Unlocking the secrets of whales through their mouths

A new study led by the University of New South Wales (UNSW) in Sydney has investigated the long, slender keratin plates that hang from the upper jaw of humpback and southern right whales, which allow them to take in many small prey at one time  (known as “baleen plates”). The goal of the research was to understand changes in these whales’ movements and behaviors over time. 

The experts discovered that changes in the dietary habits of these whales going back almost 60 years correspond with changing climate cycles. These findings suggest that it is possible to link feeding patterns with climate conditions by analyzing whale baleen.

“What is incredible is that all of this information about dietary and spatial patterns has been unlocked just through analyzing plates in their mouths,” said study lead author Adelaide Dedden, a doctoral student at UNSW. By comparing the information stored in the baleen of humpback and right whales in the Indian and Pacific Oceans with environmental data, Dedden and her colleagues have revealed how the whales’ behaviors reflected changes in climate conditions over time.

For instance, humpback whales migrating along the east coast of Australia showed signs of poorer feeding opportunities during La Niña phases (a large-scale climate cycle which drives food availability in the Southern Ocean).

“Baleen whales are enormous and need huge amounts of food. This makes them vulnerable to changes in the environment, but this is also compounded by their survival strategy,” explained study senior author Tracy Rogers, a marine ecologist at UNSW. “They fast for the long periods when they leave their productive feeding grounds to breed. That’s why they’re extremely susceptible to changes in ocean-atmospheric cycles as they can drive food availability.”

“With La Niña events predicted to increase in intensity and frequency, it unfortunately means these whales may continue to have more of these poorer feeding prospects, and we could see more strandings in the future.”

However, researchers found that humpbacks from the west coast of Australia who feed in the Indian Ocean showed increased feeding success during La Niña periods. At the same time, their east coast counterparts also seem to adapt to different feeding strategies in more temperate waters on their migration routes. These findings offer hope that these animals may turn out to be more resilient to climate change than initially thought. 

Yet, urgent actions to mitigate climate change will likely make a big difference for whale populations. “We need to act now while we still can. Acting on climate change now is good for whales but also for all of us,” Professor Rugers concluded.

The study is published in the journal Frontiers in Marine Science.

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By Andrei Ionescu, Earth.com Staff Writer