In the southwest of Ireland and the Celtic Sea (ICES divisions: 7j-g and 7aS), herring are an important commercial species to the pelagic and polyvalent fleet. Acoustic surveys are currently are the only tuning indices available for this stock. Since 2004 the survey has been fixed in October and carried out on-board the RV Celtic Explorer. During this 18 day survey (4th - 22nd October) was led by the Marine Institute and took place in the Celtic Sea where acoustic data were collected using the Simrad EK60 scientific echosounder. Biological sampling was carried out at 17 stations using a pelagic midwater trawl with all components of the catch from the trawl hauls sorted and weighed; fish and other taxa were identified to species level. Hydrographic data on temperature, depth and salinity (CTD) were collected using a calibrated Seabird 911 sampler. In addition, 23 grab samples were obtained and marine mammal and seabird surveys conducted. 30 hours of the survey were lost due to poor weather conditions. The aim of the acoustic survey is to determine the relative abundance of the target species, herring. This information is then used to determine catch rates and management advice for the following year.