Page 141 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney Regional Environmental Assessment of Renewable Energy:
Environmental Report
one of the largest in Europe consisting of a demographically healthy single population with
sightings concentrated on three main areas: The Baie du Mont Saint-Michel, the Minquiers
archipelago and the northern part of the Gulf of St. Malo (Louis et al. 2010). These sighting
areas are shown in Figure 16.
Bottlenose dolphin were the most commonly observed cetacean species in both 2011 and
2010 recorded by The Channel Sea Marine Mammal Sighting Network (representing 62% and
70% of observations respectively) (Figure 17). In 2011, 280 observations of bottlenose dolphin
were recorded with 173 sightings recorded in 2010. In both years the highest density of
sightings were in the Baie du Mont Saint-Michel and the northern part of the Gulf of St. Malo
Photographic identification also suggested a movement of bottlenose dolphins between Baie
du Mont Saint-Michel during summer and sights further west during spring (GECC, 2010;
GECC, 2011).
Distribution and Abundance Around Alderney
Bottlenose dolphin were recorded feeding within the waters around Alderney during the
OpenHydro Subsea Tidal Array Installation Seabird and Marine Mammal Monitoring including
seven pods, ranging from 2-12 individuals in the near shore environment of Longis Bay during
the survey period (Figure 18). Bottlenose dolphins were the most frequently encountered
marine mammal throughout the survey period, with an encounter rate of 0.1 individual per hour
(ARE, 2009; Entec UK Limited, 2007). No bottlenose dolphin were recorded in the seabird and
marine mammal baseline survey within the south east region of Alderney commissioned in
2010 by Alderney Commission for Renewable Energy (Alderney Wildlife Enterprise, 2011).
Harbour Porpoise (Phocoena phocoena)
Harbour porpoise distribution is restricted to temperate and sub-arctic (primarily 5-14ºC) seas
of the Northern Hemisphere. The harbour porpoise is the most commonly recorded cetacean
in UK waters, primarily occurring on the continental shelf (DECC, 2009; Reid et al. 2003). In
coastal waters, they are often encountered close to islands and headlands with strong tidal
currents (Evans et al. 2003; and DECC, 2009). Porpoise mating occurs around October with
births (usually a single calf) from March to August. Harbour porpoise have a varied diet,
exploiting seasonally abundant prey from both pelagic and demersal habitats. Small schooling
fish including herring and sprat (Clupeidae), sandeel (Ammodytidae) and members of the cod
family (Gadidae) are important food sources in UK and Irish waters (Pierpoint, 2008).
The identification of different stocks or subpopulations for harbour porpoise was undertaken by
ASCOBANS Population Structure Workshop based on genetic studies and the combining of
information from other approaches (e.g. telemetry). The workshop identified 14 distinct stocks
for the North Atlantic. The stocks relevant to UK waters are the North Eastern North Sea &
Skagerrak (NENS), South Western North Sea & Eastern Channel (SWNS), Celtic Sea (plus
South West Ireland, Irish Sea & Western Channel) (CES) and North West Ireland & West
Scotland (NWIS) (Evans and Teilmann, 2009).
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