Publication Date:
2022-05-26
Description:
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Cubaynes, H. C., Rees, W. G., Jackson, J. A., Moore, M., Sformo, T. L., McLellan, W. A., Niemeyer, M. E., George, J. C., van der Hoop, J., Forcada, J., Trathan, P., & Fretwell, P. T. Spectral reflectance of whale skin above the sea surface: a proposed measurement protocol. Remote Sensing in Ecology and Conservation, 6, (2020): 411-423, doi:10.1002/rse2.155.
Description:
Great whales have been detected using very‐high‐resolution satellite imagery, suggesting this technology could be used to monitor whales in remote areas. However, the application of this method to whale studies is at an early developmental stage and several technical factors need to be addressed, including capacity for species differentiation and the maximum depth of detection in the water column. Both require knowledge of the spectral reflectance of the various whale species just above the sea surface, as when whales bodies break the surface of the water to breath, log or breach, there is, at times, no sea water between the whale's skin and the satellite sensor. Here we tested whether such reflectance could be measured on dead whale tissue. We measured the spectral reflectance of fresh integument collected during the bowhead subsistence harvest, and of thawed integument samples from various species obtained following strandings and stored at −20°C. We show that fresh and thawed samples of whale integument have different spectral properties. The reflectance of fresh samples was higher than the reflectance of thawed samples, as integument appears to darken after death and with time, even under frozen conditions. In this study, we present the first whale reflectance estimates (without the influence of sea water and for dead tissue). These provide a baseline for additional work, needed to advance the use of satellite imagery to monitor whales and facilitate their conservation.
Description:
We are thankful for the financial support of the MAVA Foundation (project 16035 ‘Studying whales from space’), NERC, BB Roberts Fund, and the Cambridge Philosophical Society (S54/104/18) and Prescott Stranding grants to UNCW. We are also thankful to NERC Field Spectroscopy facility for lending us a ‘Spectralon’ reflectance standard. We are grateful for the incredible support from the Barrow Whaling Captains Association, the North Slope Borough Department of Wildlife Management, Emma Shanahan and the IFAW's team and Carrie Rowlands, Laura Murley and Tiffany Keenan‐Bateman from the UNCW crew for helping us sort out and access the whale integument samples. Thank you to the many staff and volunteers over the years who assisted with post‐mortem exams and collected the samples used for this study. We thank Billy Mills and Danny L. Buss for their generosity in sharing their statistical knowledge. The samples of whale integument were collected under the following permit: Stranding Agreements between the NOAA, National Marine Fisheries Service and network participants: IFAW and UNCW, NOAA stranding Letter of Authorization to UNCW, NOAA Marine Mammal Health and Stranding Response Permits 932‐1489, 932‐1905, 17355, 18786 and 18786, Authorization from the NOAA NMFS NE Regional Office, NE and SE US NMFS MMPA Regional Letters of Authorization, under NMFS permit to Dr Teri Rowles. The integument samples from the bowhead subsistence harvest used to measure the reflectance were under the NMFS Permit No. 21386, however, samples were not retained.
Keywords:
Population monitoring
;
reflectance
;
spectroradiometer
;
VHR satellite
;
whales
Repository Name:
Woods Hole Open Access Server
Type:
Article
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