New areas for porpoise conservation
7 December 2009, by Sara Coelho
Scientists have taken the first steps to protect harbour porpoises in British waters, identifying the Firth of Lorne and the Sound of Jura in the west coast of Scotland as suitable places to establish special areas of conservation.
The coastal waters between the Hebrides and the west of Scotland are home to a substantial population of harbour porpoises. But no special areas of conservation (SAC) have yet been outlined as required by European Union directives.
'It's difficult to define sites essential for the life and reproduction of harbour porpoises because although numerous, they are shy, difficult to survey and highly mobile, ranging over a wide geographic area,' says Dr Clare Embling, from the University of Aberdeen, who worked in the problem while at the Sea Mammal Research Unit.
'Using conventional visual survey methods, harbour porpoises are also extremely difficult to spot unless the sea is very calm,' she adds.
Embling and her team analysed data from a three-year survey done on board the Silurian, a Hebridean Whale and Dolphin Trust research vessel. The ship zig-zagged the seas between the Inner Hebrides and mainland Scotland, while onboard volunteers scanned the horizon looking for harbour porpoises.
The data was analysed using a purpose-built spatial statistical model, which related sightings locations with local environmental variables, such as water depth and tidal strength. The spatial model 'provides a predictive density-map of harbour porpoises and helps to identify high use areas,' explains Embling.
'Ideally, we would protect harbour porpoises over the whole Hebrides, but that is not possible,' says Embling. 'So we used the spatial model to predict where they are more likely to be.'
The spots ranked at the top of the porpoises' preference according to the model were the Firth of Lorne, the Sound of Jura and the area between Mull and the Treshnish Islands.
'These are sites where special areas of conservation for harbour porpoises would be most useful in the region,' says Embling.
Embling, C.B., et al. Using habitat models to identify suitable sites for marine protected areas for harbour porpoises (Phocoena phocoena). Biological Conservation (2009), doi:10.1016/j.biocon.2009.09.005
Interesting? Spread the word using the 'share' menu on the top right.