Data from: Echolocation detections and digital video surveys provide reliable estimates of the relative density of harbour porpoises ...

• Main Authors: Williamson, Laura D., Brookes, Kate L., Scott, Beth E., Graham, Isla M., Bradbury, Gareth, Hammond, Philip S., Thompson, Paul M.
• Format: Dataset
• Language: English
• Published: Dryad 2017
• Subjects: distance sampling; digital survey; Density Surface Modelling; Phocoena phocoena; Acoustics; availability; Harbour Porpoise; Harbour porpoise
• Online Access: https://dx.doi.org/10.5061/dryad.cf04g; https://datadryad.org/stash/dataset/doi:10.5061/dryad.cf04g

1. Robust estimates of the density or abundance of cetaceans are required to support a wide range of ecological studies and inform management decisions. Considerable effort has been put into the development of line-transect sampling techniques to obtain estimates of absolute density from aerial and boat-based visual surveys. Surveys of cetaceans using acoustic loggers or digital cameras provide alternative methods to estimate relative density that have the potential to reduce cost and provide a verifiable record of all detections. However the ability of these methods to provide reliable estimates of relative density has yet to be established. 2. These methodologies were compared by conducting aerial visual line-transect surveys (n=10 days) and digital video strip-transect surveys (n=4 days) in the Moray Firth, Scotland. Simultaneous acoustic data were collected from moored echolocation detectors (C-PODs) at 58 locations across the study site. Density surface modelling (DSM) of visual survey data was used to ... : Visual_Survey_DataR data file of the visual survey data in distance format. R Code to open the file provided in readme.txtDigital_Survey_DataR data file of the digital survey data in distance format. R Code to open the file provided in readme.txtVisual_vs_Digital_ComparisonData used for bootstrap comparison of visual and digital DSM estimates to calculate the scaling factor for digital surveys.Acoustic_DataData used for comparison of acoustic indices to estimates of relative density from DSM of visual survey data. ...