Harbour Porpoise - Phocoena phocoena

Harbour porpoise (Phocoena phocoena) are the smallest cetacean that can be found in Scottish waters, generally seen along the open coast, in shallow bays, estuaries, and sea lochs. The key identification features of harbour porpoise are their small size (around 1.5m in length) and the small, short triangular dorsal fin located halfway down its back (fig. 1) (Couzens, 2023). Main diet consists of small shoaling fish such as herring, sprat, sandeel. Harbour porpoise generally breed between May and August, peaking in June (Evans, Anderwald & Hepworth, 2008).

Range & Distribution:
Harbour porpoise are the most abundant cetacean to be found in inshore waters (Couzens, 2023) and can be seen all year round - see fig. 2 & 3 for sightings up the East coast and around Aberdeen Harbour. Peak numbers occur in August/September time (Evans, Anderwald & Hepworth, 2008).
The abundance of harbour porpoise occuring in the North Sea can be seen in fig. 4 (Gilles et al, 2023).

Factors Affecting Harbour Porpoise:
Noise pollution - for example, pile driving can impact on waiting times and displacement of harbour porpoise, but use of sound-reducing mitigation measures such as a bubble curtain have been shown to reduce this negative impact (Evans, Anderwald & Hepworth, 2008).
Other threats to harbour porpoise include incidental killing and capture as bycatch during fishing activities, reduced prey availability from fishing pressures, and coastal development (IAMMWG, Camphuysen & Siemensma, 2015).

Conservation Status:
UK Biodiversity Action Plan: Priority Species (BRIG, 2007)
Scottish Biodiversity List: Priority Species (NatureScot, 2020)
Harbour Porpoise are protected species under the European Habitats Directive.

Report any cetacean sightings to the SeaWatch Foundation or NESBReC via the links below.