A revised target strength–length estimate for blue whiting (Micromesistius poutassou): implications for biomass estimates
Acoustic abundance estimates of blue whiting have generally been higher than estimates based on catch data. One explanation has been that the relationship between acoustic target strength (TS) and length is too low and hence overestimates the number of fish.
Measurements of TS were conducted during surveys of blue whiting in March/April 2003–2007 to the west of the British Isles from several different measurement platforms, and also during August 2005 in the Norwegian Sea. Results from these experiments confirm the view that the existing TS–length relationship is too low. A new TS–length relationship is proposed that is ∼5 dB higher. Blue whiting TS is considerably higher than observed and modelled for a similar species, southern blue whiting (Micromesistius australis).