Update to the Polar Ocean Ecosystem Time-Series Western Core Box krill density

In February 2025 an acoustic trawl survey was carried out to estimate Antarctic krill (Euphausia superba) abundance in the Western Core Box (WCB) survey area to the northwest of South Georgia (in CCAMLR Subarea 48.3). The survey was run from the British Research Vessel the RRS Sir David Attenborough operating a calibrated Simrad EK80 scientific echosounder and an RMT8 net. Acoustic reflections were attributed to krill using the 3-frequency dB-differencing technique (38, 120 and 200 kHz) and estimated mean areal biomass density was 46.89 gm^-2. The acoustic transects of the survey were completed solely during daylight hours. Biomass for the WCB survey strata was estimated as 500,152 tonnes, with a CV of 47.9%.