Biomass results from the International Synoptic Krill Survey in Area 48, 2019

Results from the International Synoptic Krill Survey in Area 48, 2019, are presented. This survey covered both the strata occupied during the CCAMLR 2000 acoustic survey and the strata that comprise the regular AMLR survey. Acoustic transects (10534 n.mi), oceanographic measurements (253 casts), and trawls (164) were carried out as per survey procedures developed in 2018, which were based on the methods and procedures used in the CCAMLR 2000 krill acoustic survey. Backscatter from krill were delineated using the ‘swarms’ method and integrated to produce distribution maps of krill areal density and survey standing stock estimates. Krill areal density for the CCAMLR 2000 strata was 35.2 gm^-2, producing a standing stock estimate of 72 mt with a sampling CV of 13%. For the AMLR strata the density was 64.2 gm^-2, standing stock 8 mt, and a CV of 16%. However, the choice of krill length distributions used to convert acoustic backscatter into krill density has a significant effect on these estimates and requires further consideration.