DOI: 10.5061/dryad.25256
title: Data from: Year-round spatiotemporal distribution of harbour porpoises within and around the Maryland wind energy area

description: Offshore windfarms provide renewable energy, but activities during the
 construction phase can affect marine mammals. To understand how the
 construction of an offshore windfarm in the Maryland Wind Energy Area
 (WEA) off Maryland, USA, might impact harbour porpoises (Phocoena
 phocoena), it is essential to determine their poorly understood year-round
 distribution. Although habitat-based models can help predict the
 occurrence of species in areas with limited or no sampling, they require
 validation to determine the accuracy of the predictions. Incorporating
 more than 18 months of harbour porpoise detection data from passive
 acoustic monitoring, generalized auto-regressive moving average and
 generalized additive models were used to investigate harbour porpoise
 occurrence within and around the Maryland WEA in relation to temporal and
 environmental variables. Acoustic detection metrics were compared to
 habitat-based density estimates derived from aerial and boat-based
 sightings to validate the model predictions. Harbour porpoises occurred
 significantly more frequently during January to May, and foraged
 significantly more often in the evenings to early mornings at sites within
 and outside the Maryland WEA. Harbour porpoise occurrence peaked at sea
 surface temperatures of 5°C and chlorophyll a concentrations of 4.5 to 7.4
 mg m-3. The acoustic detections were significantly correlated with the
 predicted densities, except at the most inshore site. This study provides
 insight into previously unknown fine-scale spatial and temporal patterns
 in distribution of harbour porpoises offshore of Maryland. The results can
 be used to help inform future monitoring and mitigate the impacts of
 windfarm construction and other human activities.
description: Data for analyzing
 occurrence of harbour porpoise foraging offshore of Maryland,
 USAThese data were
 collected using C-PODs at four sites offshore of Maryland, USA from
 November 2014 to May 2016. File contains a column for the date
 (dd/mm/yyyy), Julian Day, Day, Month, Year, the Hour (in EST), Buzz type
 (0 is non-foraging, 1 is foraging), the Site (1-4), and three columns used
 solely to create the Buzz type column (autovar, forR, and
 Sum_R).Foraging_Model.txtHourly acoustic detections of harbour porpoises offshore of Maryland, USAThese data were collected using C-PODs at four sites offshore of Maryland, USA from November 2014 to May 2016. Columns include the Day, Month, Year, Hour (EST), DPM_Porp (the number of minutes in each hour with a porpoise detection), DPH_Porp (presence (1) or absence (0) of a detection in each hour), autovar (for R use only), and the site (1-4).Temporal_Model.txtComparison of predicted porpoise densities and acoustic metricsPredicted porpoise densities are courtesy of Jason J. Roberts. Acoustic data were collected from November 2014 to May 2016 offshore of Maryland, USA. Columns of importance are the site (1-4), month, Density, and the four acoustic metric columns (maximum number of hours per day with a detection, total number of hours with a detection, maximum number of hours in a day with a detection, and the proportion of days with a detection).Duke Data Comparison.txtWeekly harbour porpoise detections and environmental dataAcoustic data were collected using C-PODs at four sites offshore of Maryland, USA from November 2014 to May 2016. This data file includes the proportion of hours in each week during which porpoises were detected and corresponding median weekly sea surface temperature (SST, in celsius), the natural log of median chlorophyll a concentrations, and fraction of the moon illuminated (weekly median and mean). Week number is the ISO week date standard (ISO-8601).Environmental model.txt