Harbour porpoise (Phocoena phocoena) is listed under the Annex II of the European Habitats Directive (Directive 92/43/CEE) and Member States are required to designate special areas of conservation to protect their populations. Although harbour porpoise distribution in the Iberian Peninsula has been described, the mouth of the Douro River was never reported as part of its range of distribution.
Observations from a pier in the mouth of the Douro were carried out to monitor the presence of the harbour porpoises. A monthly measure of sightings per unit of effort was calculated. Information on the sightings, group sizes and records of the white individual is presented.
Twenty six surveys were performed resulting in 22 sightings with group size varying from one to three animals. The white individual was sighted 12 times and recorded both in photographs and video. July was the month with the lowest number of sightings per unit of effort (SPUE), while October had the highest SPUE.
Evidences, such as the presence of an easily recognizable white individual and the reports from local sea-users suggest a degree of site fidelity from this group of harbour porpoises in the mouth of the Douro River. However, further studies are needed to support the effective management and conservation of this group.