Estimate the spawning stock abundance of Blue Whiting using acoustic methods.
A pelagic trawl (5600 meshes), fitted out with an inner codend of 20 mm meshes, will be used for identifying the echotraces. For the calibration the ship has to be anchored in a sheltered location, and the echosounder transducers will be calibrated by means of suspending small tungsten-carbide spheres inside the acoustic beam. Transducers will be mounted on a retractable drop keel. The entire calibration operation will not take more than 8 hours. A CTD profile will be taken at the calibration site. No fishing will be conducted, and no other electronic instruments other than the echosounder and the CTD will be operated.
Sascha M Fassler (Institute for Marine Resources and Ecosystem Studies, IJmuiden)
ICES International Blue Whiting Survey
International Council for the Exploration of the Sea (ICES)
North East Atlantic Ocean (limit 40W)
Western Approaches and West of Ireland, 52N to 60N, 5W to 16W.