Abundance estimate and acoustic monitoring of Harbour porpoise Phocoena phocoena in the Blasket Islands cSAC

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 within the Blasket Islands candidate Special Area of Conservation (cSAC) to derive density and abundance estimates and carry out static acoustic monitoring. Single platform line-transect surveys were carried out on six days between 16 July and 1 October 2007. Distance sampling was used to derive g(0), which is the density of harbour porpoises on the track of the vessel. Passive acoustic monitoring was carried out through the deployment of self-contained click detectors called T-PODs, which identify and log the echolocation clicks of harbour porpoises.

A total of 74 tracks were surveyed of a total distance of 460 km. A total of 44 sightings of 102 individual harbour porpoise were recorded. Sightings of 25 common dolphins (Delphinus delphis), five minke whales (Balaenoptera acutoratrata) and two basking sharks (Cetorhinus maximus) were also recorded.

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Theme	Environment
Date released	2022-05-31
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 angular distance of the sighting from the vessel recorded. These data were communicated to the recorder in the wheelhouse via a 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. To assist in estimating distance, tests were carried out prior to the start of each survey by estimating distances to objects which could be verified using a Leica Rangemaster 1200. Some data was amended to comply with GDPR legislation/ open data publication guidelines. The data was collected during the Harbour porpoise survey of 16th July 2007.
Period of time covered (begin)	2007-07-01
Period of time covered (end)	2007-11-30