Scientists map southern right whale feeding grounds through skin isotope analysis
Researchers have unlocked a clearer picture of where southern right whales feed by studying the chemical makeup of their skin. A study led by scientists from Macquarie University in Australia examined skin samples to trace feeding patterns across oceans. By analyzing the ratios of carbon and nitrogen isotopes in the skin, the team built a geographic map of the whales’ foraging routes over time.
In this long-term effort, Robert Harcourt and colleagues collected 1,002 skin samples from southern right whales spanning nearly three decades, from 1994 to 2020. Each whale carries an isotopic fingerprint that reflects the marine region where it has been feeding. Those isotopes pass into the whale’s tissues, including the skin, after the animal consumes prey in different regions. Because isotope signals persist for roughly six months, scientists can reconstruct where the whales have traveled during the past half year.
Harcourt notes that tracking such large marine mammals can be challenging. The isotope technique, however, provides a practical means to identify feeding grounds and movement patterns in the Southern Ocean and adjacent seas. With this method, researchers were able to chart where southern right whales have been feeding in recent years and how their movements shift across the seasons and years [Macquarie University].
The findings show notable changes in feeding areas over the study period, a pattern linked to shifts in whale habitat use and, more broadly, to climate change. Across the South Atlantic Ocean and the southwestern Indian Ocean, whales were less likely to enter Antarctic waters during certain times, a shift that coincides with reduced krill availability in those regions. The changes point to how environmental pressures influence whale foraging behavior and habitat selection over time [Macquarie University].
On the other hand, in the Southwest Pacific, whales continued to head south at specific times of the year, indicating that krill populations remain relatively robust there. This regional variation underscores the complexity of the ocean ecosystem and how multiple factors shape whale movement in different basins [Macquarie University].
Overall, the study provides a clearer picture of how large cetaceans respond to climate-driven changes in prey distribution and suggests practical steps for protecting whale populations. By understanding where and when these animals feed, researchers can better anticipate responses to ongoing environmental change and inform conservation strategies that support the health of ocean ecosystems [Macquarie University].
This research contributes to the broader effort to monitor marine species as climate change reshapes supply chains for key prey like krill. It also highlights the value of non-invasive techniques that reveal movement patterns without the need for continuous tagging or direct observation. Protecting critical feeding habitats becomes a priority as scientists refine models of whale distribution and respond to shifting ocean conditions [Macquarie University].
Additional notes from the study acknowledge the broader context of marine fossil records and historical pollen traces that shed light on past ecosystems, adding depth to current understanding of how whales and their prey have responded to long-term environmental changes.