Dear all,
My co-authors and I are pleased to announce the Early View of our publication
in Marine Mammal Science:
Alvarado DC, Robinson PW, Frasson NC, Costa DP, Beltran RS. Calibration of
aerial photogrammetry to estimate elephant seal mass. Mar Mam Sci. 2020;1-9.
https://doi.org/10.1111/mms.12714 <https://doi.org/10.1111/mms.12714>
Abstract
Body mass measurements can provide important insights into the physiology and
foraging ecology of marine mammals. Unmanned aerial system (UAS) photogrammetry
offers a method that is safer for both animals and researchers and is
logistically simpler than traditional weighing methods. Our objectives were:
1) to evaluate the accuracy of UAS photogrammetry for estimating the mass of
adult female northern elephant seals and 2) to examine the effect of body
position on mass estimates obtained using UAS. We analyzed a series of UAS
images of 22 adult female northern elephant seals (Mirounga angustirostris) of
known mass at Año Nuevo Reserve (San Mateo County, California, USA). Complete
body areas (hereafter, footprint areas, measured in m2) of seals in a dorsal
(laying on ventral surface, N=45) or lateral (laying on side, N=7) body
position were measured in ImageJ using the standard polygon area selection tool
and compared to mass measurements. Linear regressions of measured mass against
footprint suggest that mass is more strongly related to dorsal footprints (R2=
0.895, N=45) than lateral footprints (R2= 0.822, N=7). Residual error ranged
from -68.7 to +69.3 kg and seal mass was estimated with a mean error of 7.7 kg,
or 2.4%, of total body mass. With the predictive models found, UAS
photogrammetry will allow us to expand our knowledge of seasonal energetic
intake and expenditure, especially in large-bodied and fully aquatic species in
remote areas. Mass measurements can inform ecosystem-based resource management
by providing information about the inter-annual productivity of the ocean
environment and in turn individual, population, and ecosystem-level health in
marine mammals.
The publication can be found at this link: http://dx.doi.org/10.1111/mms.12714
<http://dx.doi.org/10.1111/mms.12714>
PDF requests can be sent to dical...@ucsc.edu <mailto:dical...@ucsc.edu>
Best regards,
Diana Alvarado
_______________________________________________
MARMAM mailing list
MARMAM@lists.uvic.ca
https://lists.uvic.ca/mailman/listinfo/marmam
