This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new study led by University of Hawai'i (UH) at Mānoa researchers reveals how extreme ocean warming disrupts whale metabolism, nutrition and reproductive success and what the developing 2026–2027 El Niño could mean next. As climate change drives increasingly intense marine heat waves, scientists are uncovering how these extreme warming events disrupt the biology of humpback whales.
Earlier reports from NOAA, academic researchers and regional monitoring programs documented troubling symptoms during the 2014–2016 Pacific marine heat wave, known as the Blob: fewer humpback whale sightings in Hawai'i and Alaska, declines in calf numbers and widespread signs of nutritional stress. Until now, the physiological mechanisms behind these population‑level changes remained unclear. The study, published in iScience, provides the missing link.
"These findings give us a window into how whales actually cope with extreme environmental stress," said lead author Ching-Tsun Chang, a former graduate student in the Department of Oceanography at the UH Mānoa School of Ocean and Earth Science and Technology and now an assistant professor at National Sun Yat-sen University, Taiwan. "We've known from previous reports that humpback whales declined in number and body condition during the Blob. What we show here is the physiological story behind those patterns: how whales adjust their metabolism, how nutrient use shifts and how reproduction may be compromised." To understand how whales responded physiologically, researchers analyzed nearly eight years of biochemical records preserved in the baleen of stranded female humpbacks from Hawai'i.
Baleen grows continuously, creating a natural timeline of metabolic signals. "Baleen is an extraordinary archive," said co-author Kristi West, director of the UH Health and Stranding Lab and associate researcher in Human Nutrition, Food and Animal Sciences at the UH Mānoa College of Tropical Agriculture and Human Resilience. "It lets us reconstruct an animal's nutritional and reproductive history with fine detail.
By pairing these biochemical records with bioenergetic models, we can finally see how climate extremes ripple through a whale's body." Using compound‑specific isotope analysis of amino acids paired with bioenergetic models, which are computer models that estimate how animals use and allocate energy, the team reconstructed how whales routed nutrients and mobilized energy reserves before, during and after the heat wave. The results reveal the physiological mechanisms behind previously observed declines. During the heat wave, whales essentially "powered down," slowing their metabolism to stretch limited food supplies.
This lack of nutrition made early pregnancy harder to maintain, even if whales became pregnant. Additionally, one whale's decades-long history shows the cumulative toll of environmental change, with its baleen preserving a five‑year record of how shifting ocean conditions affected its body late in life. Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. d research that matter—daily or weekly.
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