This survey is part of the ICES coordinated international hydro acoustic survey for blue whiting which is carried out yearly in March/April. The other participating countries are the Faroe Islands, Ireland, Norway and Russia. IMARES, Institute for Marine Resources & Ecosystem Studies, part of Wageningen University and Research, has participated in the international North-East Atlantic hydro acoustic survey for blue whiting since 2004. The survey is part of the EU Data Collection Framework. The aim of this survey is to provide an abundance estimate of the whole North-East Atlantic blue whiting population and to determine the spatial distribution at this time of year. This estimate is used as a tuning index by the ICES Working Group on Widely Distributed Stocks (WGWIDE) to determine the size of the population. In this report the results are presented of the survey west of Ireland, carried out by FRV “Tridens”. A secondary objective during the survey is to gather information on the distribution of non-commercial mesopelagic species.