Dataset: Krill swarms detected with active acoustic EK80 onboard small boat surveys in Palmer Deep Canyon, Antarctica during January-March 2020

Day trip active acoustic surveys were conducted from Palmer Station Field Season aboard RHIB twice weekly from January-March 2020 using a hull-mounted SIMRAD EK80 single-beam, single frequency (120 kHz) echosounder (Kongsberg Maritime) along transects shown in Figure 1A (Veatch et al 2025).

The echosounder was configured with a 1 s ping rate, 512 µs pulse duration, and 24 µs sampling duration. Calibrations of the echosounder were performed in the vicinity of Palmer Deep Canyon using a tungsten sphere (diameter = 38.1 mm) during February, 2020. Acoustic data were processed in Myriax Echoview software version 11.1 following methods from (Tarling, Klevjer et al. 2009) and (Tarling, Thorpe et al. 2018). Raw data were processed to consider the echosounder calibration and in situ ocean acoustic conditions via incorporation of onboard CTD data, and to remove background noise and other interferences via the Background Noise Removal (De Robertis and Higginbottom 2007) and Impulse Noise Removal (Ryan, Downie et al. 2015) algorithms in Echoview. Krill were then detected using a target strength threshold of -70 dB to -30 dB(Tarling, Klevjer et al. 2009, Tarling, Thorpe et al. 2018) in Echoview following similar parameterization and protocols to (Nardelli, Cimino et al. 2021) and (Reiss, Cossio et al. 2021) (Figure 4, Veatch et al 2025).