Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea

Determining the position of animals at sea can be particularly difficult and yet, accurate range and position of animals at sea are essential to answer a wide range of biological questions. Shore-based theodolite techniques have been used in a number of studies to examine marine mammal movement patt...

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Published in:Journal of Marine Biology
Main Authors: Sagnol, Ophélie, Reitsma, Femke, Richter, Christoph, Field, Laurence H.
Format: Article in Journal/Newspaper
Language:English
Published: 2014
Subjects:
Online Access:http://hdl.handle.net/1807/81695
https://doi.org/10.1155/2014/267917
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spelling ftunivtoronto:oai:localhost:1807/81695 2023-05-15T17:59:24+02:00 Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea Sagnol, Ophélie Reitsma, Femke Richter, Christoph Field, Laurence H. 2014-01-22 http://hdl.handle.net/1807/81695 https://doi.org/10.1155/2014/267917 en eng Ophélie Sagnol, Femke Reitsma, Christoph Richter, and Laurence H. Field, “Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea,” Journal of Marine Biology, vol. 2014, Article ID 267917, 8 pages, 2014. doi:10.1155/2014/267917 https://doi.org/10.1155/2014/267917 http://hdl.handle.net/1807/81695 Copyright © 2014 Ophélie Sagnol et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. CC-BY Journal Article 2014 ftunivtoronto https://doi.org/10.1155/2014/267917 2020-06-17T12:09:35Z Determining the position of animals at sea can be particularly difficult and yet, accurate range and position of animals at sea are essential to answer a wide range of biological questions. Shore-based theodolite techniques have been used in a number of studies to examine marine mammal movement patterns and habitat use, offering reliable position measurements. In this study we explored the accuracy of theodolite measurements by comparing positional information of the same objects using two independent techniques: a shore-based theodolite station and an onboard GPS over a range of 25 km from the shore-based station. The technique was developed to study the habitat use of sperm whales (Physeter macrocephalus) off Kaikoura, New Zealand. We observed that the position accuracy fell rapidly with an increase in range from the shore-based station. Results showed that the horizontal angle was accurately determined, but this was not the case for the vertical angle. We calibrated the position of objects at sea with a regression-based correction to fit the difference in distance between simultaneously recorded theodolite fixes and GPS positions. This approach revealed the necessity to calibrate theodolite measurements with objects at sea of known position. Peer Reviewed Article in Journal/Newspaper Physeter macrocephalus University of Toronto: Research Repository T-Space New Zealand Journal of Marine Biology 2014 1 8
institution Open Polar
collection University of Toronto: Research Repository T-Space
op_collection_id ftunivtoronto
language English
description Determining the position of animals at sea can be particularly difficult and yet, accurate range and position of animals at sea are essential to answer a wide range of biological questions. Shore-based theodolite techniques have been used in a number of studies to examine marine mammal movement patterns and habitat use, offering reliable position measurements. In this study we explored the accuracy of theodolite measurements by comparing positional information of the same objects using two independent techniques: a shore-based theodolite station and an onboard GPS over a range of 25 km from the shore-based station. The technique was developed to study the habitat use of sperm whales (Physeter macrocephalus) off Kaikoura, New Zealand. We observed that the position accuracy fell rapidly with an increase in range from the shore-based station. Results showed that the horizontal angle was accurately determined, but this was not the case for the vertical angle. We calibrated the position of objects at sea with a regression-based correction to fit the difference in distance between simultaneously recorded theodolite fixes and GPS positions. This approach revealed the necessity to calibrate theodolite measurements with objects at sea of known position. Peer Reviewed
format Article in Journal/Newspaper
author Sagnol, Ophélie
Reitsma, Femke
Richter, Christoph
Field, Laurence H.
spellingShingle Sagnol, Ophélie
Reitsma, Femke
Richter, Christoph
Field, Laurence H.
Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea
author_facet Sagnol, Ophélie
Reitsma, Femke
Richter, Christoph
Field, Laurence H.
author_sort Sagnol, Ophélie
title Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea
title_short Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea
title_full Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea
title_fullStr Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea
title_full_unstemmed Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea
title_sort correcting positional errors in shore-based theodolite measurements of animals at sea
publishDate 2014
url http://hdl.handle.net/1807/81695
https://doi.org/10.1155/2014/267917
geographic New Zealand
geographic_facet New Zealand
genre Physeter macrocephalus
genre_facet Physeter macrocephalus
op_relation Ophélie Sagnol, Femke Reitsma, Christoph Richter, and Laurence H. Field, “Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea,” Journal of Marine Biology, vol. 2014, Article ID 267917, 8 pages, 2014. doi:10.1155/2014/267917
https://doi.org/10.1155/2014/267917
http://hdl.handle.net/1807/81695
op_rights Copyright © 2014 Ophélie Sagnol et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
op_rightsnorm CC-BY
op_doi https://doi.org/10.1155/2014/267917
container_title Journal of Marine Biology
container_volume 2014
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