The Research Vessel R/V Song of the Whale (which is owned by the International Fund for Animal Welfare, and managed and operated by Marine Conservation Research Ltd) would be used to conduct offshore visual and acoustic surveys using a team of 8-10 personnel. The southern North Sea survey area would be treated as a single survey block and randomly generated tracklines will be planned to provide equal coverage probability. Acoustic surveys, using software developed by IFAW (e.g. RainbowClick and Logger) will take place for 24 hrs/day in sea condition up to Beaufort 6; visual surveys may be conducted when appropriate during daylight hours in suitable sea state conditions (Beaufort three or less) from sightings platforms with eye-heights of 5 and/or 11 m above sea-level. Dual-platform effort may be used to assess the probability of detection on the transect line and to allow for responsive movement of animals in relation to the ship. The survey vessel and all necessary equipment will be provided by MCR for a period of 15 days of survey effort; in addition, nominated participants could take part in a training course – covering planning, set up, data collection and analysis - prior to the survey itself, as well as the survey. Additionally, the aim is to coordinate vessel surveys with aerial survey effort, undertaken by Belgian, Dutch and German partners. Currently, dedicated aerial surveys for harbour porpoises are conducted over Belgian, Dutch and German waters. With partners coordinating efforts, this would provide a unique opportunity to compare the different survey methodologies. Aerial survey data from previous surveys may be available for comparative analysis. Outputs to include: - Practical, theory and boat-based training of ASCOBANS nominated personnel. - Cruise report upon completion of vessel survey. - Final report upon completion of post-process data analysis. - Publication of results in peer-reviewed journal as appropriate, including aerial survey data and analysis if possible.