The integrated response of blue whales and krill to climate change

Investigators: Dr. Leigh Torres, Dr. Dawn Barlow, Dr. KC Bierlich, Dr. Kim Bernard, Dr. Holger Klinck

Ocean ecosystems are experiencing significant and rapid impacts of climate change, yet the cascading effects on marine organisms are largely unknown and understudied. It is therefore critical to understand how rapid environmental change will impact the availability and quality of key prey species, and consequently how these changes will impact predator health and population resilience. The goal of the SAPPHIRE project is to identify and describe the impacts of environmental variation on the physiology of a crucial marine prey species (krill) and a model marine predator (blue whale). The project will examine how changing ocean conditions affect the availability and quality of krill, and impact blue whale body condition, endocrinology (i.e., hormone levels), and foraging and reproductive effort.

Species resilience to climate change over shorter timescales will be determined by the fitness and fecundity of individuals mediated through behavioral and physiological response pathways. This project aims to describe the co-response of marine prey (krill) and predator (blue whale) health to environmental variation at both individual and population levels, enabling a comprehensive understanding of impacts on species fitness under climate change conditions. Our research takes place in the South Taranaki Bight region of Aotearoa New Zealand, which is home to an upwelling system that supports aggregations of krill and a unique population of blue whales that is present year-round (see the OBSIDIAN project). Over three years (2024-2026) we will use interdisciplinary methods that include controlled experiments on krill to assess their response to elevated temperature, surveys for blue whale occurrence paired with active acoustic assessment of krill availability, Unoccupied Aircraft System (UAS; “drone”) flights over whales to determine body condition and potential pregnancy, tissue biopsy sampling to quantify hormone levels, and passive acoustic monitoring to describe rates of foraging and reproductive calls by blue whales. Our broad objectives are to:

  1. Assess the mechanistic response of krill to variable environmental conditions through controlled experiments and field collections,
  2. Document the physiological response of blue whales to changes in environment and prey,
  3. Describe relationships between environmental conditions and blue whale foraging and reproductive behavior, and
  4. Integrate these components to develop novel Species Health Models (SHM) to predict prey and predator population response to rapid environmental change.

Through the SAPPHIRE project, we will develop a framework for understanding the health impacts of environmental change on krill and blue whales, which can in turn inform management decisions based on relevant thresholds. Furthermore, the outputs of SAPPHIRE will be well-suited for the design and testing of dynamic management approaches. Finally, the SAPPHIRE project will harness the iconic status of blue whales to inform society about the significant impacts of climate change on the world’s oceans, so that publicity and regulatory action based on this flagship species can enhance awareness and motivate behavioral change.


Blog posts:

Learning from the unexpected: the first field season of the SAPPHIRE project

How big, how blue, how beautiful! Studying the impacts of climate change on big (and beautiful) blue whales

It's getting hot in here: studying the impacts of marine heatwaves on krill, life-blood of the ocean

Phases and feelings of the scientific journey

Blue whales, krill, and climate change: introducing the SAPPHIRE project



New Zealand Department of Conservation

K. Lisa Yang Center for Conservation Bioacoustics, Cornell University

Cetacean Conservation Genomics Laboratory, Oregon State University

Dr. Phil Sutton, New Zealand Institute of Water and Atmospheric Research (NIWA), Ltd.

Dr. Svenja Halfter, New Zealand Institute of Water and Atmospheric Research (NIWA), Ltd.

Dr. Emma Carroll, University of Auckland

Dr. Rochelle Constantine, University of Auckland

Dr. Kathleen Hunt, George Mason University

Dr. Nick Kellar, NOAA Southwest Fisheries Science Center

Dr. Nicholas Wolff, The Nature Conservancy



Comparing blue whale morphology between productive coastal ecosystems

Blue whales are globally distributed, with distinct populations that feed in productive coastal regions worldwide. Comparing blue whale populations between different regions can therefore shed light on how different life history adaptations to ecosystem function may influence population resilience to environmental change. We are therefore comparing ecosystem characteristics and blue whale morphology between foraging grounds. This comparative aspect of the SAPPHIRE project is a pilot phase that uses data already collected. Specifically, we are comparing the oceanography of three blue whale foraging grounds: (1) Monterey Bay, USA, (2) South Taranaki Bight, Aotearoa New Zealand, and (3) Corcovado Gulf, Chile. Additionally, we are using drone images to compare the morphology and body condition of the blue whale populations that feed in each of these three regions.

Our findings to-date illustrate how these three blue whale populations are “shaped by their environment”, with morphological differences that reflect differences in the annual cycles of upwelling and productivity on the three foraging grounds.

New data collection efforts will allow for more comprehensive comparisons between regions and blue whale populations, which in turn may shed light on the resilience or vulnerability of these populations to environmental change.



Dr. Will Oestreich, Monterey Bay Aquarium Research Institute

Dr. John Ryan, Monterey Bay Aquarium Research Institute 

Dr. Gustavo Chiang, Universidad Andrés Bello

Dr. Matt Leslie, United States Geological Survey

Dr. John Durban, Oregon State University

Dr. Michael Moore, Woods Hole Oceanographic Institute 

Dr. Jeremy Goldbogen, Stanford University

Dr. Dave Johnston, Duke University



Barlow, D. R., Bierlich, K. C., Oestreich, W. K., Chiang, G., Durban, J. W., Goldbogen, J. A., Johnston, D. W., Leslie, M. S., Moore, M. J., Ryan, J. P. & Torres, L. G. (2023). Shaped by their environment: variation in blue whale morphology across three productive coastal ecosystems. Integrative Organismal Biology5(1), obad039.



Orange County Community Foundation


We are launching a multidisciplinary research program to investigate the resilience of the world’s largest animal—the blue whale—to changing ocean conditions.