Tridens 08-013

Cruise plan

Cruise Info. 
Ship name (ship code)Tridens (64T2)
Cruise identifier08-013
Cruise period2008-03-13 — 2008-04-03
Port of departureScheveningen, Netherlands
Port of returnScheveningen, Netherlands
ObjectivesInternational North East Atlantic hydro acoustic survey for blue whiting. The survey is coordinated by ICES and has been executed annually. Ireland, Russia, Iceland, Denmark, Faroe Islands and Norway also participate in the survey. The purpose of the survey is to estimate the blue whiting stock of the North East Atlantic. ICES uses this estimation is as a "tuning index" to assess the North East Atlantic blue whiting stock. For this survey a Simrad 38kHz splitbeam transducer was used together with a Simrad EK60 echo sounder. The applied method was echo integration. By sailing transects over the survey area, the total acoustic cross-section can be calculated by surface area sampled. Trawling identified species composition of localised schools. The length composition of each species was determined. Blue whiting was examined on age and fecundity from which a split up stock structure was made. Blue whiting where found throughout the survey area associated with the continental shelf edge but showed a clear increase reaching the northern part of the Tridens survey area.

Although a loss of 24 hours due to bad weather and other circumstances the survey has been very successful in terms of acoustic milage, number of trawl hauls, acoustic data quality and communication.
Chief scientistSytse Ybema (Institute for Marine Resources and Ecosystem Studies, IJmuiden)
Coordinating bodyInternational Council for the Exploration of the Sea (ICES)
NPRCTridens 08-013 NPRC tridens_20080317.pdf (0.09 MB) 
Ocean/sea areas 
GeneralNorth East Atlantic Ocean (limit 40W)
SpecificContinental Shelf edge west of UK and Ireland.