Samenvatting

In Pembrokeshire/Wales harbor porpoise (Phocena phocena) make daily use of Ramsey sound, a narrow ocean channel characterized by strong tidal currents. The sound is an important socializing and feeding area for porpoise and was designated marine special area of conservation (MSAC) in 2004. The region is popular for leisure boating and vessel based wildlife watching. A voluntary code of conduct was put in place to protect the animals from disturbance through vessels but proved ineffective, leaving the animals with little protection. A dedicated land based survey was carried out between April-July 2012 in order to assess boating activity in the sound and potentially associated signs of disturbance in porpoise. It was found that 58% of the total number of vessels observed in the sound are wildlife watching boats. They followed the code requirements to a certain degree, however especially in the narrow centre of the sound high speeds up to 42 knots were observed and frequent porpoise encounters suggest high vulnerability of the animals. The majority of porpoise sightings (56%) were made in the southern area of the sound where foraging activity was found on a daily basis. Porpoise showed signs of disturbance on some occasions but seemed to ignore vessels on others. No direct responses of foraging porpoise to vessels were observed. They continued their activity with vessels in close proximity. Based on the precautionary principle, a need for protective measures was indicated. Recommendations for improved management including dynamic no take zones, communication with land based observers and statutory measures if porpoise can proved to be resident in Ramsey sound, as well as future research goals were developed. The results of this study will help to increase the chance for long-term sustainable use of the region by both humans and animals.