[MARMAM] PhD: Harbour porpoise habitat preferences and distribution

Cormac Booth cgb8 at st-andrews.ac.uk
Wed Sep 7 03:19:48 PDT 2011

Dear MARMAMers,

Last year, the following PhD thesis was completed investigating harbour
porpoises habitat preferences and distribution using six years of visual and
acoustic line-transect survey data west of Scotland. Habitat preferences and
distribution were assessed at a range of temporal and spatial scales. In
addition the PhD looks at the prevalence and received levels of Airmar seal
scarers deployed and the potential for these sounds to impact porpoises via
cumulative exposures.

It is now publicly available for download from:

Thesis citation:
Booth, 2010. Variation in habitat preference and distribution of harbour
porpoises west of Scotland. PhD Thesis. Scottish Oceans Institute.
University of St Andrews. pp264.


“The waters off the west coast of Scotland have one of the highest densities
of harbour porpoise (*Phocoena phocoena*) in Europe. Harbour porpoise are
listed under Annex II of the EU Habitats Directive, requiring the
designation of Special Areas of Conservation (SACs) for the species’
protection and conservation.

The main aim of this thesis is to identify habitat preferences for harbour
porpoise, and key regions that embody these preferences, which could
therefore be suitable as SACs; and to determine how harbour porpoise use
these regions over time and space. Designed visual and acoustic
line-transect surveys were conducted between 2003 and 2008. GAMs with
Generalised Estimating Equations (GEEs) were used to determine relationships
between the relative density of harbour porpoise and temporally and
spatially variable oceanographic covariates. Predictive models showed that
depth, slope, distance to land and spring tidal range were all important in
explaining porpoise distribution. There were also significant temporal
variations in habitat use. However, whilst some variation was observed among
years and months, consistent preferences for water depths between 50 and 150
m and highly sloped regions were observed across the temporal models.
Predicted surfaces revealed a consistent inshore distribution for the
species throughout the west coast of Scotland. Regional models revealed
similar habitat preferences to the full-extent models, and indicated that
the Small Isles and Sound of Jura were the most consistently important
regions for harbour porpoise, and that given this consistency; these regions
could be suitable as SACs.

The received levels and impacts of Airmar seal scarers on distribution and
habitat use of porpoises were also investigated, and there were indications
that these devices have the potential to displace harbour porpoise and that
the potential for auditory injury should be considered in response to
cumulative exposures.

These results can be considered in the assessment of sites for SAC
designation, and in

implementing appropriate conservation measures for harbour porpoise.”

Please contact me on cgb8 at st-andrews.ac.uk if you have any questions or
would like to discuss the work in more detail.

Best regards,
Cormac Booth
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