JNCC Report No: 543
JNCC Report No: 543 Analysis of long-term effort-related land-based observations to identify whether coastal areas of harbour porpoise and bottlenose dolphin have persistent high occurrence and abundance Peter G.H. Evans, Graham J. Pierce, Gemma Veneruso, Caroline R. Weir, Danielle Gibas, Pia Anderwald and M. Begoña Santos Revised version June 2015 © JNCC, Peterborough 2015 ISSN 0963 8901 For further information please contact: Joint Nature Conservation Committee Monkstone House City Road Peterborough PE1 1JY www.jncc.defra.gov.uk This report should be cited as: Evans, P.G.H., Pierce, G.J., Veneruso, G., Weir, C.R., Gibas, D., Anderwald, P. and Begoña Santos, M. 2015. Analysis of long-term effort-related land-based observations to identify whether coastal areas of harbour porpoise and bottlenose dolphin have persistent high occurrence & abundance. JNCC report No. 543, JNCC, Peterborough. Summary Dedicated shore watches for cetaceans have been conducted at a number of sites around the UK since 1965. Here, over 75,000 hours of watches and c50,000 associated sightings of bottlenose dolphin and harbour porpoise from 678 sites around the coasts of Britain are analysed, in order to determine whether areas of persistent high occurrence and relative abundance of the two species can be identified. Average sightings rates (sightings per unit hour of search) and count rates (animals per unit hour of search) were calculated from each site over the full time period that watches were conducted. For use in statistical modelling, results were summarised by site and by day (thus eliminating within-day autocorrelation), and records associated with high Beaufort ‘sea state’ and short observation duration were filtered out.
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