Status of the FIBEX acoustic data from the west Atlantic

Data from the FIBEX acoustic survey in the West Atlantic sector have been re-examined to check the consistency of krill abundance estimates derived from different survey vessels. There is a good level of consistency between the results from four of the vessels, Itzumi, Dr Eduardo L Holmberg, Odysee and Walther Herwig. While there is an error factor due to the combination of data collected at 50kHz (Walther Herwig survey) with data collected at 120 kHz (all other vessels), it is concluded that this does not materially affect on the estimated biomass.
The data from the Profesor Siedlecki survey do not provide estimates that are consistent with the other surveys. The authors can find no explanation for this difference.