Using remote sensing to detect whale strandings in remote areas: The case of sei whales mass mortality in Chilean Patagonia

Autoři: Peter T. Fretwell aff001;  Jennifer A. Jackson aff001;  Mauricio J. Ulloa Encina aff002;  Vreni Häussermann aff003;  Maria J. Perez Alvarez aff005;  Carlos Olavarría aff008;  Carolina S. Gutstein aff009
Působiště autorů: British Antarctic Survey, Madingley Road, Cambridge, England, United Kingdom aff001;  Aquatic Animal Rescue and Conservation Unit, National Fisheries and Aquaculture Service of Chile, Valparaiso, Chile aff002;  Pontificia Universidad Católica de Valparaíso, Facultad de Recursos Naturales, Escuela de Ciencias del Mar, Avda. Brazil, Valparaíso, Chile aff003;  Huinay Scientific Field Station, Valparaíso, Chile aff004;  Escuela de Medicina Veterinaria, Facultad de Ciencias, Universidad Mayor, Santiago, Chile aff005;  Instituto de Ecología y Biodiversidad, Facultad de Ciencias, Universidad de Chile, Santiago, Chile aff006;  Centro de Investigación Eutropia, Santiago, Chile aff007;  Centro de Estudios Avanzados en Zonas Aridas (CEAZA), La Serena, Chile aff008;  Lab. Ontogenia y Filogenia, Depto. Biologiía, Fac. Ciencias, Universidad de Chile, Santiago, Chile aff009;  Consultora Paleosuchus Ltda, oficina C, Providencia, Santiago, Chile aff010
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article
doi: 10.1371/journal.pone.0222498


We test the ability of Very High Resolution satellite (VHR) imagery to detect stranded whales using both manual and automated methods. We use the 2015 mass mortality event in the Gulf of Penas locality, central Patagonia, Chile, as an initial case study. This event was the largest known mass mortality of baleen whales, with at least 343 whales, mainly sei whales (Balaenoptera borealis), documented as stranding. However, even with such a large number of whales, due to the remote location of the gulf the strandings went unrecorded for several weeks. Aerial and boat surveys of the area were conducted two to four months after the mortality event. In this study we use 50cm resolution WorldView2 imagery to identify and count strandings from two archival images acquired just after the stranding event and two months before the aerial and ground surveys, and to test manual and automated methods of detecting stranded whales. Our findings show that whales are easily detected manually in the images but due to the heterogeneous colouration of decomposing whales, spectral indices are unsuitable for automatic detection. Our satellite counts suggest that, at the time the satellite images were taken, more whales were stranded than recorded in the aerial survey, possibly due to the non-comprehensive coverage of the aerial survey or movement of the carcases between survey acquisition. With even higher resolution imagery now available, satellite imagery may be a cost effective alternative to aerial surveys for future assessment of the extent of mass whale stranding events, especially in remote and inaccessible areas.

Klíčová slova:

Beaches – Boats – Image analysis – Islands – Marine mammals – Whales – Remote areas – Geological surveys


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