Field comparison of Antarctic krill (Euphausia superba) backscatter and aggregation types using NORTEK and SIMRAD echosounders

• DOI: 10.1093/icesjms/fsae093
• Publication Date: 2024-07-25T02:15:47Z
• Authors: Pavanee Annasawmy; John K Horne; Christian S Reiss; George R Cutter; Gavin J Macaulay
• Keywords: Antarctic krill; Backscatter (email); Echo sounding

Abstract Temporal distributions of Antarctic krill (Euphausia superba) density and aggregation types were characterized compared using Nortek Signature100 SIMRAD Wideband Autonomous Transceiver (WBAT) upward-looking echosounders. Noise varied between the two With Signature100, it was necessary to correct data for background, transient, impulse noises, while WBAT needed be corrected background noise only. For selected regions with no visible backscatter, signal-to-noise ratio Sv values (i.e. signal level) did not vary Surface echo backscatter similar during time periods. Descriptive metrics used quantify spatial temporal vertical distributions: volume mean depth, center mass, inertia, equivalent area, index, proportion occupied. Krill differed instruments but detected at depths. aggregations identified each mooring location classified in three based on morphological characteristics. Each type shape spatially separated moorings, acoustic similar. The a lower number (n = 133) 707). Although both can autonomous deployment sampling over extended periods, there is strong caveat use due significant differences characteristics detection.