Harbour Porpoise Surveys 2008

Published by: Department of Housing, Local Government, and Heritage

Licensed under: Creative Commons Attribution 4.0

Category: Environment

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A survey of harbour porpoises (Phocoena phocoena) was carried out at five sites (North County Dublin, Dublin bay, Cork coast, Roaringwater bay cSAC and Galway bay) to derive density and abundance estimates. Single platform line-transect surveys were carried out on six days at each site between July and September 2008. Distance sampling was used to derive g(0), which is the density of harbour porpoises on the track of the vessel. Abundance estimates were calculated using the track-line as the sample and the sighting as the observation.

During 28 survey days a total of 354 track-lines were surveyed for a total distance of nearly 20,000 km in seastate ≤2. From the 269 sightings of a total of 496 individual harbour porpoise were recorded. There were 13 sightings with a total of 171 common dolphins (Delphinus delphis), eight sightings of single minke whales (Balaenoptera acutoratrata) and one sighting of 20 bottlenose dolphins (Tursiops truncatus). Five sightings with a total of 18 dolphins were not identified to species level.

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Theme	Environment
Date released	2022-07-06
Date updated	2023-11-20
Dataset conforms to these standards	The INSPIRE Directive or INSPIRE lays down a general framework for a Spatial Data Infrastructure (SDI) for the purposes of European Community environmental policies and policies or activities which may have an impact on the environment.
Rights notes	{http://creativecommons.org/licenses/by/4.0/,"Copyright Government of Ireland. This dataset was created by National Parks and Wildlife Service, Department of Housing, Local Government and Heritage. This copyright material is licensed for re-use under the Creative Commons Attribution 4.0 International licence. http://creativecommons.org/licenses/by/4.0/",otherRestrictions}
Update frequency	Other
Language	English
Geographic coverage in GeoJSON format	{"type":"Polygon","coordinates":[[[-10.650444030762, 50.807923689449],[-10.650444030762, 55.993470564449], [-5.289115905762, 55.993470564449], [-5.289115905762, 50.807923689449], [-10.650444030762, 50.807923689449]]]}
Spatial Reference Systems (SRS)	WGS 84 (EPSG:4326)
Vertical Extent	{"verticalDomainName": "EPSG Projection 5731 - Malin Head height", "minVerticalExtent": "0", "maxVerticalExtent": "1014"}
Provenance information	During each transect the position of the survey vessel was tracked continuously through a GPS receiver fed directly into a laptop while survey effort, including environmental conditions (sea-state, wind strength and direction, glare etc.) were recorded directly onto LOGGER software (©IFAW) every 15 minutes. When a sighting was made the position of the vessel was recorded immediately and the angle of the sighting from the track of the vessel and the perpendicular distance of the sighting from the vessel recorded. These data were communicated to the recorder in the wheelhouse via VHF radio. The angle was recorded to the nearest degree via an angle board attached to the vessel immediately in front of each observer. Accurate distance estimation is essential for distance sampling. At some sites during each survey an orange buoy225mm in diameter was towed 200m astern of the observers’ position on the survey vessel. This provided reference point against which to estimate distances. The location data in this shapefile was collected in Roaringwater Bay candidate SAC between July and September 2008.
Period of time covered (begin)	2008-07-01
Period of time covered (end)	2008-09-30