Estimates of krill biomass with commercial significance in small-scale management units applying geostatistics techniques

The analysis of krill density and biomass distributions was made by the example of SGE and SGW which are located in ecologically crucial areas affecting land-based predators around South Georgia, being the traditional krill fishing areas. The data collected during the 2000 CCAMLR Survey and Russian survey 2002 were used. Processing of the acoustic survey data in 2000-2002 was made applying geostatistical methods.
It was revealed significant inter-annual and seasonal variability of the standing stock and its fishable part in each SSMU. The relationship between the biomass available to fishery and the total biomass may vary by SSMUs, e.g. in SGE this relationship based on the two surveys data constituted 0.18 and 0.40, and in SGW - 0.06 and 0.24 respectively . The survey 2002 indicated that the significant differences between commercial biomass can be obtained for areas with the comparable total biomass, e.g. total biomass constituted 1.0587 mlt for eastwards of 37°W and 1.000mt for westward of 37°W , but commercial biomass was 0.41985 mlt and 0.24 mlt respectively.
The option “standing stock of krill in the SSMUs”, considered for allocating this catch limit among the SSMUs in the Scotia Sea, has to be supplemented with the fishable biomass estimate within SSMUs.
A success of assessment of the standing stock and its fishable part will be related to the problem of acoustic data processing improvement. The methods specially designated for spatially distributed data are preferable. Special researches are necessary to compare the precision of different methods of spatial data processing, such as classic geostatic methods, Maximum Entropy method, Bayesian geostatic methods based on the maximum Entropy principle