Marine heatwaves are not a dominant driver of change in demersal fishes

• Published in: Nature
• Main Authors: Fredston, Alexa L., Cheung, William W. L., Frölicher, Thomas L., Kitchel, Zoë J., Maureaud, Aurore A., Thorson, James T., Auber, Arnaud, Mérigot, Bastien, Palacios-Abrantes, Juliano, Palomares, Maria Lourdes D., Pecuchet, Laurène, Shackell, Nancy L., Pinsky, Malin L.
• Other Authors: Northwest Fisheries Science Center (NWFSC), NOAA National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA), Laboratoire Ressources Halieutiques de Boulogne (LRHBL), Unité Halieutique Manche Mer du Nord (HMMN), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), MARine Biodiversity Exploitation and Conservation - MARBEC (UMR MARBEC ), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Center for Limnology, University of Wisconsin-Madison, Hopkins Marine Station Stanford, Stanford University, European Project: 820989,H2020-EU.3.5.1.,COMFORT(2019)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDV]Life Sciences [q-bio]; Arctic
• Online Access: https://hal.science/hal-04204170; https://doi.org/10.1038/s41586-023-06449-y

International audience Marine heatwaves have been linked to negative ecological effects in recent decades1,2. If marine heatwaves regularly induce community reorganization and biomass collapses in fishes, the consequences could be catastrophic for ecosystems, fisheries and human communities3,4. However, the extent to which marine heatwaves have negative impacts on fish biomass or community composition, or even whether their effects can be distinguished from natural and sampling variability, remains unclear. We investigated the effects of 248 sea-bottom heatwaves from 1993 to 2019 on marine fishes by analysing 82,322 hauls (samples) from long-term scientific surveys of continental shelf ecosystems in North America and Europe spanning the subtropics to the Arctic. Here we show that the effects of marine heatwaves on fish biomass were often minimal and could not be distinguished from natural and sampling variability. Furthermore, marine heatwaves were not consistently associated with tropicalization (gain of warm-affiliated species) or deborealization (loss of cold-affiliated species) in these ecosystems. Although steep declines in biomass occasionally occurred after marine heatwaves, these were the exception, not the rule. Against the highly variable backdrop of ocean ecosystems, marine heatwaves have not driven biomass change or community turnover in fish communities that support many of the world’s largest and most productive fisheries.