The blues are back in town: recap of the SAPPHIRE 2025 field season

By Dr. Dawn Barlow & Dr. Leigh Torres, OSU Department of Fisheries, Wildlife, and Conservation Sciences, Geospatial Ecology of Marine Megafauna Lab

As the sun set on February 16^th, the R/V Star Keys pulled into Wellington Harbour, marking the end of the 2025 SAPPHIRE field season. The crew and science team returned to shore after a packed, productive, and successful three weeks at sea studying the impacts of environmental change on blue whales and krill in the South Taranaki Bight, Aotearoa New Zealand.

In stark contrast to the 2024 field season, which featured dense and seemingly endless layers of gelatinous salps in the water and no krill or blue whales in the South Taranaki Bight, the 2025 field season was filled with blue whales and krill. In our three weeks aboard our research vessel Star Keys this year, we observed 66 blue whales, most of which were lunge feeding at the surface on dense patches of krill. We also collected krill for on-board respiration experiments and to be frozen to measure their lengths, weights, and caloric content. We recovered two hydrophones that recorded blue whale calls for the past year, and replaced them with two more. We collected identification photos, skin and blubber tissue samples for genetic and hormone analysis, and flew drones over almost all whales we encountered to measure body condition and morphology. We conducted water column profiles to measure the oceanography of the region, and mapped the prey field as we surveyed using a scientific echosounder.

Around the world, we are currently bearing witness to environmental change. Our survey last year in 2024 was a reminder of the challenges these blue whales face to survive and thrive in an increasingly unpredictable ocean. This year was a poignant example of the vibrant marine life that exists here in the South Taranaki Bight when ocean conditions align more closely with what is expected, and of the incredible resilience of these animals as they navigate changing waters. These contrasting conditions over multiple years are key to our understanding as we study the impacts of climate change on krill and blue whales through the SAPPHIRE project.

The fieldwork we do to collect these data is motivated by scientific questions, management needs, and fascination with this ecosystem. But ultimately, what makes fieldwork possible and memorable is the people. We are deeply grateful for the many partners on the SAPPHIRE project. The 2025 science team was made up of Leigh Torres, Dawn Barlow, KC Bierlich, Kim Bernard (Oregon State University), Mike Ogle, and Ros Cole (Department of Conservation). The outstanding crew of the R/V Star Keys (Western Work Boats), Josh Fowden, Dave Futter, and Jordy Maiden-Drum, kept us safe, sailing, fed, and happy for three intense weeks. We are also grateful for our shore support, including our colleagues at Cornell University’s Yang Center for Conservation Bioacoustics, NIWA, the Marine Mammal Institute at Oregon State University, and the University of Auckland. Importantly, we deeply appreciate our many stakeholders who help us share, learn, and make our findings meaningful, including the Department of Conservation, the people of Aotearoa, and iwi across our study region, especially Ngāruahine who hosted us at the Rangatapu Marae for a profound hui with a powerful pōwhiri and critical wānanga of knowledge sharing.

Now the next phase of the work begins. We have many terabytes of data to process, analyze, interpret, and share. We will certainly have our hands full. But while we are at our computers back in Oregon, we will be holding the memories of this field season close: The brilliant turquoise glow of a blue whale just below the surface, the sound of the deep exhalation as the whale comes up for air, and the awe of looking into a blue whale’s eye as it engulfs a dense swarm of krill; The golden sunset lighting and moon rise over Cape Farewell, and Mount Taranaki towering over the blue waters of the South Taranaki Bight; The giddy exclamations or silent awe of those of us privileged to spend time in these waters observing these animals, and the visions that linger just behind our eyelids as we fell into an exhausted sleep. We will see what the next year holds for the SAPPHIRE team and the blue whales and krill of the South Taranaki Bight.

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