The Geometer: A New Device for Recording Angles in Visual Surveys
The Geometer is a new handheld USB device that facilitates a relatively accurate measurement of the declination to a target with instantaneous recording of this and other data. The Geometer offers several advantages over traditional clinometers used in aerial surveys, including easier target pinpointing and tracking, more consistent angle measurements, and integration with software data collection packages. In this note we provide technical specifications for the device and its associated software, and describe a new aerial survey data collection programme that takes full advantage of the features of the Geometer. We have tested this device extensively during aerial surveys and highlight the utility of the hardware as well as ways in which the technology could be improved.
Borchers, D. L., Marques, T., Gunnlaugsson, T. and Jupp, P. (2010). Estimating Distance Sampling Detection Functions when Distances Are Measured with Errors. Journal of Agricultural, Biological, and Environmental Statistics, 15(3), 346–361. https://doi.org/10.1007/s13253-010-0021-y
Borchers, D. L., Pike, D. G., Gunnlaugsson, Th. and Víkingsson, G. A. (2009). Minke whale abundance estimation from the NASS 1987 and 2001 aerial cue–counting surveys taking appropriate account of distance estimation errors. NAMMCO Scientific Publications, 7, 95–110. https://doi.org/10.7557/3.2708
Buckland, S. T., Anderson, D., Burnham, K., Laake, J., Borchers, D. and Thomas, L. (2001). Introduction to distance sampling estimating abundance of biological populations. Oxford University Press.
Hansen, R. G., Boye, T. K., Larsen, R. S., Nielsen, N. H., Tervo, O., Nielsen, R. D., Rasmussen, M. H., Sinding, M. H. S., & Heide-Jorgensen, M. P. (2019). Abundance of whales in West and East Greenland in summer 2015. NAMMCO Scientific Publications, 11. https://doi.org/10.7557/3.4689
Hiby, A. R. and Hammond, P. S. (1989). Survey techniques for estimating current abundance and monitoring trends in abundance of cetaceans. Report of the International Whaling Commission, Special Issue 11, 47–80.
Lawson, J. W. and Gosselin, J. F. (2018). Estimates of cetacean abundance from the 2016 NAISS aerial surveys of eastern Canadian waters, with a comparison to estimates from the 2007 TNASS. SC/25/AE/09 for the NAMMCO Scientific Committee.
Leaper, R., Burt, L., Gillespie, D. and Macleod, K. (2010). Comparisons of measured and estimated distances and angles from sightings surveys. Journal of Cetacean Research and Management, 11, 229–237.
North Atlantic Marine Mammal Commission (NAMMCO). (2013a). Report of the NAMMCO Scientific Committee Working Group on Survey Planning. NAMMCO Annual Report 2012, 392–475. Retrieved from https://nammco.no/topics/annual-reports/
North Atlantic Marine Mammal Commission (NAMMCO). (2013b). Report of the Nineteenth Meeting of the Scientific Committee. NAMMCO Annual Report 2012, 263–550. Retrieved from https://nammco.no/topics/annual-reports/
North Atlantic Marine Mammal Commission (NAMMCO). (2016). Report of the NAMMCO Scientific Committee Survey Planning Working Group. NAMMCO Annual Report 2015, 305–318. Retrieved from https://nammco.no/topics/annual-reports/
Pike, D. G. (2013). Aerial survey: State of the art and recommendations for the next T-NASS. NAMMCO Annual Report 2012, 411–441. Retrieved from https://nammco.no/topics/annual-reports/
Pike, D. G., Gunnlaugsson, T., Mikkelsen, B., Halldórsson, S. D., Vikingsson, G. A., Acquarone, M. and Desportes, G. (2020). Estimates of the abundance of cetaceans in the Central North Atlantic from the T-NASS Icelandic and Faroese ship surveys conducted in 2007. NAMMCO Scientific Publications, 11. https://doi.org/10.7557/3.5269
Pike, D. G., Gunnlaugsson, T., Sigurjonsson, J. and Vikingsson, G. A. (2020). Distribution and abundance of cetaceans in Icelandic waters over 30 years of aerial surveys. NAMMCO Scientific Publications, 11. https://doi.org/10.7557/3.4805
Copyright (c) 2020 Rikke Guldborg Hansen, Daniel Pike, Baldur Thorgilsson, Thorvaldur Gunnlaugsson, Jack Lawson
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).