Mass estimation of Weddell seals through photogrammetry
Food resources of pelagic marine predators have traditionally been difficult to monitor and annual monitoring of food-resource availability is not currently feasible for the Weddell seal (Leptonychotes wedellii) population in Erebus Bay, Antarctica. Body mass measurements of parturient females, or t...
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Montana State University - Bozeman, College of Letters & Science
2004
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ftmontanastateu:oai:scholarworks.montana.edu:1/1538 2023-05-15T13:54:59+02:00 Mass estimation of Weddell seals through photogrammetry Ireland, Darren Scott Chairperson, Graduate Committee: Robert Garrott 2004 application/pdf https://scholarworks.montana.edu/xmlui/handle/1/1538 en eng Montana State University - Bozeman, College of Letters & Science https://scholarworks.montana.edu/xmlui/handle/1/1538 Copyright 2004 by Darren Scott Ireland Weddell seal Photogrammetry Thesis 2004 ftmontanastateu 2022-06-06T07:29:20Z Food resources of pelagic marine predators have traditionally been difficult to monitor and annual monitoring of food-resource availability is not currently feasible for the Weddell seal (Leptonychotes wedellii) population in Erebus Bay, Antarctica. Body mass measurements of parturient females, or their weaned pups, on an annual basis may be used as an indicator of food availability during the previous year and also provide a link between population vital rates and environmental fluctuation. Traditional methods of acquiring mass measurements, including physical restraint and/or chemical immobilization, limit the ability to sample adequately large numbers of individuals from the population of interest. Previous researchers have developed methods to estimate the mass of large seals using scaled photographs, but later application of these methods have not explicitly included uncertainty around estimates derived from predictive equations. I therefore developed the equipment and methods for estimating the mass of Weddell seals using digital photographs and image-analysis software. I then applied the method at a small scale to determine how prediction intervals may be incorporated into calculations based on mass estimates and what affect the explicit use of these intervals would have on the ability to detect differences between the mass of individuals or groups of seals. Scaled photographs of adult female and pup Weddell seals were taken from overhead, ground-level side, and ground-level head or tail perspectives. Morphometric measurements from scaled photographs (photogrammetric measurements) were then correlated using regression against the measured mass at the time of photography. Sampling occurred throughout the nursing period in order to build regression models over a wide range of masses. Resulting regression models predict the mass of adult female seals to within ±13.8% of estimated mass, and ±25.9% of estimated mass for pups. In an application of the method, differences in mass transfer between experienced and ... Thesis Antarc* Antarctica Weddell Seal Weddell Seals Montana State University (MSU): ScholarWorks Erebus Bay ENVELOPE(166.517,166.517,-77.733,-77.733) Weddell |
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Open Polar |
collection |
Montana State University (MSU): ScholarWorks |
op_collection_id |
ftmontanastateu |
language |
English |
topic |
Weddell seal Photogrammetry |
spellingShingle |
Weddell seal Photogrammetry Ireland, Darren Scott Mass estimation of Weddell seals through photogrammetry |
topic_facet |
Weddell seal Photogrammetry |
description |
Food resources of pelagic marine predators have traditionally been difficult to monitor and annual monitoring of food-resource availability is not currently feasible for the Weddell seal (Leptonychotes wedellii) population in Erebus Bay, Antarctica. Body mass measurements of parturient females, or their weaned pups, on an annual basis may be used as an indicator of food availability during the previous year and also provide a link between population vital rates and environmental fluctuation. Traditional methods of acquiring mass measurements, including physical restraint and/or chemical immobilization, limit the ability to sample adequately large numbers of individuals from the population of interest. Previous researchers have developed methods to estimate the mass of large seals using scaled photographs, but later application of these methods have not explicitly included uncertainty around estimates derived from predictive equations. I therefore developed the equipment and methods for estimating the mass of Weddell seals using digital photographs and image-analysis software. I then applied the method at a small scale to determine how prediction intervals may be incorporated into calculations based on mass estimates and what affect the explicit use of these intervals would have on the ability to detect differences between the mass of individuals or groups of seals. Scaled photographs of adult female and pup Weddell seals were taken from overhead, ground-level side, and ground-level head or tail perspectives. Morphometric measurements from scaled photographs (photogrammetric measurements) were then correlated using regression against the measured mass at the time of photography. Sampling occurred throughout the nursing period in order to build regression models over a wide range of masses. Resulting regression models predict the mass of adult female seals to within ±13.8% of estimated mass, and ±25.9% of estimated mass for pups. In an application of the method, differences in mass transfer between experienced and ... |
author2 |
Chairperson, Graduate Committee: Robert Garrott |
format |
Thesis |
author |
Ireland, Darren Scott |
author_facet |
Ireland, Darren Scott |
author_sort |
Ireland, Darren Scott |
title |
Mass estimation of Weddell seals through photogrammetry |
title_short |
Mass estimation of Weddell seals through photogrammetry |
title_full |
Mass estimation of Weddell seals through photogrammetry |
title_fullStr |
Mass estimation of Weddell seals through photogrammetry |
title_full_unstemmed |
Mass estimation of Weddell seals through photogrammetry |
title_sort |
mass estimation of weddell seals through photogrammetry |
publisher |
Montana State University - Bozeman, College of Letters & Science |
publishDate |
2004 |
url |
https://scholarworks.montana.edu/xmlui/handle/1/1538 |
long_lat |
ENVELOPE(166.517,166.517,-77.733,-77.733) |
geographic |
Erebus Bay Weddell |
geographic_facet |
Erebus Bay Weddell |
genre |
Antarc* Antarctica Weddell Seal Weddell Seals |
genre_facet |
Antarc* Antarctica Weddell Seal Weddell Seals |
op_relation |
https://scholarworks.montana.edu/xmlui/handle/1/1538 |
op_rights |
Copyright 2004 by Darren Scott Ireland |
_version_ |
1766261207472275456 |