Preliminary report on the FIBEX acoustic work to estimate the abundance of Euphausia superba

The FIBEX acoustic work to estimate the abundance of krill (Euphausia superba) is briefly reported. A multi-ship echo integrator survey was carried out in three separate areas of the Southern Ocean, totalling about 1.3 million square nautical miles. Communal analysis of the data at an international data workshop indicated a total abundance of about 78 million t in these areas, giving a mean density of 17.5g per square metre. The standard deviation was estimated as 19.5 million t, taking only the survey variance into account. Of particular interest was the apparent finding of the major portion of the biomass between 60°and 80°E, rather than in the Scotia Sea/Antarctic Peninsula region. It is stressed, however, that the results of the workshop are preliminary, and must be checked against estimates made by the individual FIBEX participants in their own areas. On the basis of the workshop results and previous knowledge on the large-scale distribution of the species, the total krill biomass at the time of the survey is tentatively estimated to have been between 200 and 600 million t