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Using aerial photogrammetry to detect changes in body condition of endangered southern resident killer whales

2018; Inter-Research; Volume: 35; Linguagem: Inglês

10.3354/esr00883

1863-5407

Holly Fearnbach, JW Durban, DK Ellifrit, KC Balcomb,

Aerospace Engineering and Energy Systems

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 35:175-180 (2018) - DOI: https://doi.org/10.3354/esr00883 ESR Special: Drones in conservation research NOTE Using aerial photogrammetry to detect changes in body condition of endangered southern resident killer whales Holly Fearnbach1,3,*, John W. Durban2, David K. Ellifrit1, Kenneth C. Balcomb1 1Center for Whale Research, 355 Smuggler’s Cove Road, Friday Harbor, WA 98250, USA 2Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 8901 La Jolla Shores Dr., La Jolla, CA 92307, USA 3Present address: SR3, SeaLife Response, Rehabilitation and Research, PO Box 1404, Mukilteo, WA 98275, USA *Corresponding author: hfearnbach@sealifer3.org ABSTRACT: The endangered population of southern resident killer whales Orcinus orca is hypothesized to be food-limited, but uncertainty remains over if and when the availability of their primary prey, Chinook salmon Oncorhynchus tshawytscha, is low enough to cause nutritional stress. To measure changes in body condition, we collected 1635 measurable images from a helicopter hovering 230-460 m above whales, and linked these to individuals with distinctive natural markings. Head width (HW), measured at 15% of the distance between the blowhole and the dorsal fin (BHDF), was measured from images of 59 individuals in 2008 (from a population of 84) and 66/81 individuals in 2013, enabling assessment of between-year changes for 44 individuals (26 females, 18 males). Of these, 11 had significant declines in the ratio of HW/BHDF compared to 5 with significant increases. Two whales with declines died shortly after being photographed, suggesting a link between body condition and mortality. Most (8/11) of the significant declines in condition were from 1 social pod (J-pod), and all the whales that increased in condition were from one of the other 2 pods, K‑pod (n = 3) and L-pod (n = 2). Notably, 11/16 whales that changed condition were reproductive-aged females and there were no adult males with significant changes. This likely reflects the increased energetic costs of lactation to reproductive females, and the nutritional help provided to adult males through prey sharing. These data demonstrate the utility of aerial photogrammetry as a non-invasive approach for providing quantitative data on body condition, and support monitoring the condition of reproductive females as key indicators of nutritional stress. KEY WORDS: Orca · Photogrammetry · Nutritional stress · Salmon · Body condition Full text in pdf format PreviousNextCite this article as: Fearnbach H, Durban JW, Ellifrit DK, Balcomb KC (2018) Using aerial photogrammetry to detect changes in body condition of endangered southern resident killer whales. Endang Species Res 35:175-180. https://doi.org/10.3354/esr00883 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 35. Online publication date: April 05, 2018 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2018 Inter-Research.