Blue Whiting Acoustic Survey Cruise Report March 28- April 16, 2011

Abstract

Acoustic surveys on blue whiting (Micromesistius poutassou) spawning aggregations in the northeast Atlantic have been carried out by the Institute of Marine Research (IMR) Norway since the early 1970s. In the early 1980s a coordinated acoustic survey approach was adopted, with both Russia and Norway participating to estimate the size of this migratory stock within the main spawning grounds to the west of Ireland and Britain. Since 2004, an International coordinated survey program has expanded to include vessels from the EU (Ireland and the Netherlands) and the Faroes. Due to the highly migratory nature of the stock a large geographical area has to be surveyed. Spawning takes place from January through to April along the shelf break from the southern Porcupine Bank area northwards to the Faroe Shetland Ridge including offshore areas as the Rosemary, Hatton and Rockall Banks. Peak spawning occurs from early March to mid April and acoustic surveys are timed to occur during this phase. To facilitate a more coordinated spatio-temporal approach to the survey participating countries meet annually to discuss survey methods and define target areas at the ICES led Working Group of Northern Pelagic Ecosystem Surveys (WGNAPES). Data from the annual spawning stock abundance survey (March/April, western waters), juvenile surveys (May, Norwegian Sea and January-March, Barents Sea trawl survey) and commercial landings data are presented annually at the ICES Working Group of Widely Distributed Stocks (WGWDS). Ultimately, combined data inputs into the management and catch advice for this international cross boundary stock. The 2011 survey was part of an International collaborative survey using the vessels RV Celtic Explorer (Ireland), RV Fridtjof Nansen (Russia), RV Tridens (Netherlands) and the RV Magnus Heinason (Faroes) and the RV G.O. Sars (Norway). The total combined area coverage extended from the Faroe Islands in the north (60.30°N) to south of Ireland (52°N), with east -west extension from 6°-17° W. International survey participants meet shortly after the survey to present data and produce a combined relative abundance and biomass index the blue whiting spawning stock in western waters. The combined survey report is presented annually at the WGNAPES meeting held in August and made available to the WGWDS assessment group.