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

Autor: Carlos Olavarría, Carolina S. Gutstein, Peter T. Fretwell, Maria J. Perez Alvarez, Mauricio J. Ulloa Encina, Vreni Häussermann, Jennifer A. Jackson
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Satellite Imagery
0106 biological sciences
Topography
Aerial survey
Beaches
Marine and Aquatic Sciences
Transportation
01 natural sciences
Geological Surveys
Satellite imagery
Chile
Geographic Areas
Mammals
Islands
Multidisciplinary
biology
Geography
Eukaryota
Geology
Remote sensing (archaeology)
Vertebrates
Medicine
Engineering and Technology
Cartography
Environmental Monitoring
Research Article
Imaging Techniques
Science
Sei Whales
Marine Biology
Image Analysis
Research and Analysis Methods
010603 evolutionary biology
Remote Areas
biology.animal
Humans
Animals
14. Life underwater
Mortality
Marine Mammals
Landforms
Balaenoptera
Whale
010604 marine biology & hydrobiology
Organisms
Whales
Correction
Biology and Life Sciences
Geomorphology
biology.organism_classification
Boats
Mass mortality
Baleen
Remote Sensing Technology
Amniotes
Earth Sciences
Zdroj: PLoS ONE
PLoS ONE, Vol 14, Iss 10, p e0222498 (2019)
ISSN: 1932-6203
Popis: 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.
Databáze: OpenAIRE
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