CSI part of groundbreaking whale study published in the Proceedings of the National Academy of Sciences (PNAS)

Posted: February 28, 2023

A new study released in the Proceedings of the National Academy of Sciences (PNAS), makes a significant discovery about the feeding habits of the Southern Right Whale in the Southern Ocean that could have profound impacts on the protection of the species and the ecosystems they rely on. 

In the article titled “Long-term stability in the circumpolar foraging range of a Southern Ocean predator between the eras of whaling and rapid climate change”, Seth Newsome, a professor of Biology and associate director of the Center for Stable Isotopes (CSI), Geraldine Busquets-Vass, a postdoctoral scientist working at CSI and the Department of Biology, along with collaborators from 14 countries conducted a truly unique study on the foraging habits of this species.

Traditionally, the southern right whale was thought to forage on copepods and krill at high latitude polar feeding grounds in the Summer. More than 95% of the global population of southern right whales was killed due to commercial whaling and this, combined with the effects of global climate change, spurred the team to look at how this was affecting the habitats that they rely on for food.  

The study used commercial and scientific datasets that spanned decades, an approach that Newsome says, “shows how comparison of modern and historical datasets can provide insights into how species have responded to different stressors over the past several centuries.”

Using stable isotope analysis, which allows researchers to identify foraging habitats, the team analyzed 1,002 Southern Right Whale skin samples collected from seven different wintering grounds across six genetically distinct populations across the Southern Hemisphere. The samples spread across three decades, providing a significant timeline for researchers to compare current data to. 

In addition to the samples, records from American whaling vessels between the years of 1792 and 1912, along with Soviet whaling vessel records between the years of 1961 and 1968 were also compiled. 

Says Newsome, “This impressive dataset represents a collaboration among many researchers from all over the world that were willing to share data to produce this range wide examination of southern right whale ecology.”

Another unique aspect of the study included the development of a model that produced a map of the isotope composition of phytoplankton across the entire Southern Ocean. By comparing this map to the right whale isotope data, researchers were able to identify which regions of the ocean are critical foraging areas, and how this has changed over the past several decades.  

These distributions were compared with historical whaling records to show that their predisposition to foraging at mid-latitudes has not changed over the past several centuries. This not only suggests that their migratory memory did not affect their foraging patterns but might also serve as a buffer for the species from climate change if polar habitats continue to change faster than temperate ones. 

This discovery will inform a number of useful global assessments in regards to protecting the species. Knowing where they feed will allow for continued study of those areas in order to monitor the effects of climate change on the species as well as the ecosystems they rely on for survival. 

Newsome’s research interests focus on studying the ecology and eco-physiology of animals, specifically what resources (food and water) they require to be successful. He also studies this topic across time by examining species in modern and ancient ecosystems to better understand animal behavioral and ecological flexibility, which may inform how they will respond to ongoing environmental change

PNAS is a prestigious peer-reviewed journal for the multidisciplinary sciences and was established in 1912. It publishes over 3,500 research papers annually.