CE0704 Blue Whiting Biomass Assessment Survey

An acoustic survey targeting blue whiting (Micromesistius poutassou) spawning and post spawning aggregations in the north east Atlantic in 2007.

Spawning takes place from January through to April along the shelf edge 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 between mid-March and mid April and acoustic surveys are timed to occur during this phase.

The 2007 survey was part of an International collaborative survey using the vessels RV “Celtic Explorer” (Marine Institute, Ireland), RV “Atlantida” (AtlantNIRO, Russian Federation), RV “Tridens” (IMARES, Netherlands) and the RV “Magnus Heinason” (FRS, Faroes) and the FV “Eros” (IMR commercial charter).

This survey covered the area to the west of the British Isles, starting off the west coast of Ireland at the shelf break and progressing northwards to the Hebrides. Westward extension reached out to the 18°W, taking in the eastern and western flanks of the Rockall Bank and eastern slopes of the Hatton Bank. The survey began in the south and worked in a northerly progression following migration pathways of blue whiting.

A parallel transect design was adopted with transects running perpendicular to the lines of bathymetry where possible. Acoustic data were collected using the Simrad ER60 scientific echosounder.

Biological sampling was done using a single pelagic midwater trawl. Fish samples were divided into species composition by weight. Species other than the blue whiting were weighed as a component of the catch. Measurements of blue whiting lengths were recorded. Age, length, weight, sex, maturity and stomach fullness data were recorded.

No marine mammal or seabird counts were undertaken during this years survey.

Oceanographic data on temperature, depth and salinity (CTD) were collected at set stations.