https://doi.org/10.82144/62e61838 https://seamap.env.duke.edu/dataset/1281 https://www.gbif.org/dataset/424d81c1-d67a-4791-8a89-f445b9569abe https://obis.org/dataset/ab514637-a4ea-40b3-80a1-356a079e34f0 Peter Gill Blue Whale Study Inc. Primary contact pete@bluewhalestudy.org http://www.bluewhalestudy.org OBIS-SEAMAP Marine Geospatial Ecology Lab, Duke University

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seamap-contact@duke.edu https://seamap.env.duke.edu OBIS-SEAMAP Marine Geospatial Ecology Lab, Duke University

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seamap-contact@duke.edu https://seamap.env.duke.edu distributor Peter Gill Blue Whale Study Inc. Primary contact pete@bluewhalestudy.org http://www.bluewhalestudy.org owner 2025-07-31 eng Original provider: Blue Whale Study Inc. Dataset credits: Blue Whale Study Inc. Abstract: Wind-forced cold water upwelling occurs seasonally along the continental shelf of south-east Australia, where pygmy blue whales aggregate to forage. Seasonality and variability are apparent for both blue whale encounter rates and upwelling, within and between seasons. Here we quantify upwelling variability over 11 seasons (2001/02 to 2011/12) and relate it to blue whale encounter rates. Two indices, cumulative wind stress (Intensity) quantifying physical forcing, and surface chlorophyll-a (chl-a) quantifying the ocean’s biological response, revealed variability in upwelling at a variety of temporal scales. Within seasons, upwelling Intensity peaked during February, and chl-a during February–March. Blue whale encounter rate from 52 aerial surveys was modelled against upwelling indices and the climate signal SAM (Southern Annular Mode), at individual survey- and aggregated season-levels, using General Additive Models (GAMs). Survey-level GAMs showed that encounter rate increased with increasing chl-a, and with increasing upwelling Intensity to a point beyond which further increases in Intensity resulted in declining encounter rates. This indicated the importance of productivity, as well as relaxation of upwelling, in producing optimal blue whale foraging conditions. In exploratory season-level models, a strong influence of SAM was apparent, with higher encounter rates associated with positive SAM during the preceding 12 months. Including chl-a improved the model, indicating that both broad-scale climatic signals inherently incorporating environmental variability and uncertainty, as well as more proximal regional factors may influence blue whale occurrence in the study area. Measuring the complex relationships between whale occurrence and upwelling is complicated by the fact that the population of blue whales using the Bonney Upwelling is open, and moves between alternate foraging areas. The findings were interpreted in the context of blue whale foraging ecology in this system. Occurrence GBIF Dataset Type Vocabulary: http://rs.gbif.org/vocabulary/gbif/dataset_type.xml Observation GBIF Dataset Subtype Vocabulary: http://rs.gbif.org/vocabulary/gbif/dataset_subtype.xml Marine Biology Visual sighting Marine Animal Survey Marine mammals Visual Sighting Aircraft N/A This work is licensed under a Creative Commons Attribution (CC-BY) 4.0 License. https://seamap.env.duke.edu/dataset/1281 Oceans,Australia 139.52 143.364 -37.531 -39.41 2007-11-09 2012-03-28 Scientific names are based on the Integrated Taxonomic Information System (ITIS). subspecies Balaenoptera musculus brevicauda Pygmy blue whale Relate variability in blue whale relative abundance to variability in upwelling off southern Australia notPlanned Peter Gill Blue Whale Study Inc. Primary contact pete@bluewhalestudy.org http://www.bluewhalestudy.org NA NA NA Peter Gill owner NA zd_1281 2025-07-31T16:40:00-04:00 dataset Gill, P. 2015. Blue Whale Study aerial surveys, southern Australia, 2007-2012. Version 1.0.0. Dataset published in OBIS-SEAMAP. https://doi.org/10.82144/62e61838. OBIS-SEAMAP Dataset Page UTF-8 Interactive map https://seamap.env.duke.edu/dataset/1281 FGDC Metadata UTF-8 XML https://seamap.env.duke.edu/dataset/1281/fgdc EML Metadata UTF-8 XML https://seamap.env.duke.edu/dataset/1281/eml OBIS-SEAMAP zd_1281 zd_1281 Pirzl, R.; Gill, P.; Morrice, M.; Garcia-Rojas, M.; Levings, A.; Van Ruth, P. 2015. Blue Whale Occurrence Related to Variability in a Coastal Upwelling System. PLOS ONE (submitted).