The salp species Salpa thompsoni was collected using depth-stratified net sampling conducted across six Southern Ocean locations during nine sampling years between 1989 and 2018. This dataset accounts for 13 day-night pairs and 10 single tows (6 daytime, 4 nighttime) collected across multiple research cruises (SO891, TAN1516, PS112, AG57, TAN0802, LMG09-01, LMG10-01, LMG11-01, LMG17-01) that were conducted in the Bransfield Strait, Chatham Rise, Elephant Island, Lazarev Sea, Ross Sea, and the Western Antarctic Peninsula. Salps were sampled using MOCNESS-1 (1 m² mouth area, 200 µm mesh), Rectangular Midwater Trawls (RMT-1, 1 m² mouth area, 332 µm mesh; RMT-8, 8 m² mouth area, 4.5 mm mesh; multi-RMT-8+1, combination of RMT-1 and RMT-8), and Juday nets (0.8 m² mouth area, 176 µm mesh), with depth-discrete sampling intervals spanning from the surface to, in some cases, 1200 m. Salp life cycle stage (LCS: blastozooid, oozoid), and occasionally developmental stage, and oral-atrial length (OAL, mm) were recorded for each individual, with salps assigned to three size classes based on maturity. For each depth stratum, abundance estimates (ind. m⁻³) were calculated by dividing the number of individuals by the volume of water filtered, then scaling by depth strata thickness if needed. This dataset comprehensively describes S. thompsoni abundance, stratified by depth, according to life cycle stage and size class, offering key insights into diel vertical distribution and regional variability.

Further funding: Ministry for Business, Innovation, and Employment (MBIE) of New Zealand Royal Society of New Zealand Marsden Fund University of British Columbia's Graduate Fellowship International Doctoral Fellowship granted by the University of British Columbia