Humpback whales are extraordinary creatures, reaching lengths of up to 42 feet and weighing as much as 77,000 pounds. These gentle giants undertake one of nature’s most epic journeys, migrating across thousands of miles between feeding and breeding grounds. Their annual migration puts tremendous demand on their fat reserves, especially during long stretches without feeding. Studying these majestic animals is vital because changes in their body mass reveal not only how well individual whales cope, but also serve as indicators of ocean health, krill abundance, and the broader impacts of climate change.

A team of researchers from Australia’s Griffith University has undertaken a groundbreaking program to study the effects of these migration rituals on humpback whales. The study was led by Alexandre Bernier-Graveline, a PhD candidate with the university’s Southern Ocean Persistent Organic Pollutants Programme. Bernier-Graveline’s research bridges marine biology and energy ecology, using innovative tools to track how much energy migrating whales expend and how it influences their survival and reproduction.

One of the innovative tools that Bernier-Graveline and his team rely on is drone technology. They use the aerial vehicles to monitor the body condition of humpback whales during migration between Antarctic feeding grounds and breeding grounds off Colombia. These drones capture high-resolution overhead imagery, which scientists then transform into accurate measurements of body volume and fat. This drone-based photogrammetry offers a noninvasive and effective way to assess whale health over vast distances and timeframes.

The drones collect overhead images that are converted from pixels into real-life dimensions, allowing researchers to estimate body mass, fat reserves, and volume loss. The drones are indispensable for gathering data across remote regions like the Western Antarctic Peninsula and Colombian waters, and their ability to take precise sequential measurements makes it possible to monitor individual whales repeatedly.

The data collected by the team were striking. On average, individual humpback whales lose approximately 36 percent of their body mass during migration, which corresponds to about 24,250 pounds of blubber. That is roughly the same weight as three pickup trucks or about 160 average-sized adults. Additionally, this loss reflects staggering energy expenditure, equal to nearly 125,500 pounds of Antarctic krill and about 46.8 million kilocalories of energy.

As Bernier-Graveline puts it, “Southern hemisphere humpback whales depend on Antarctic krill for their annual energy requirements, fueling their long migrations between feeding and breeding grounds.” He also noted, “We found the whales were at their fattest in early autumn, March to May, and slimmest by late spring, August to December, showing a dramatic seasonal change in body mass.”

The numbers highlight just how dramatically humpback whales gain and lose weight each year and emphasize the importance of abundant feeding grounds to sustain their long migrations. Moreover, this drone-derived information provides crucial context for conservationists. “By linking migration and reproductive energy cost to krill biomass,” Bernier-Graveline stated, “the findings provided key ecological context for understanding how environmental changes, such as krill population fluctuations, could impact whale populations in the future.”

Martin van Aswegen, a PhD candidate from the Marine Mammal Research Program at the University of Hawaiʻi at Mānoa, reported similar successes with drone imagery. van Aswegen used drones to study individual lactating humpback whales. His work revealed that lactating mothers lost nearly 214 pounds of blubber per day, and over 60 days, that corresponded to roughly 50 tons of krill consumed.

The importance of these observations cannot be overstated. Tracking body mass via drones gives researchers a window into how whales allocate energy between feeding, migration, and reproduction. Such data are critical when many marine ecosystems face shifting prey availability and changing climate patterns. Together, the work by Bernier-Graveline and van Aswegen shows that drone-based photogrammetry is a powerful tool for marine science.

By combining precise aerial measurements with long-distance tracking and statistical analysis, researchers are uncovering essential insights into whale physiology, population resilience, and ecosystem dynamics. These results can inform policy decisions, marine management, and conservation strategies aimed at protecting feeding habitats and mitigating climate or human-induced stressors. As the world’s oceans continue to warm and human pressures grow, tools such as drones may prove indispensable for safeguarding humpback whales and the marine ecosystems they inhabit.

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