Active acoustics data from the French PIRATA cruises in the tropical Atlantic, 2015-2025.

This paper presents an active acoustics dataset derived from the French component of the PIRATA (Prediction and Research Moored Array in the Tropical Atlantic) program in the Tropical Atlantic and the Gulf of Guinea. This program, initiated in 1997 with the deployment of a buoy network, has offered the opportunity to collect multifrequency acoustic data since 2015. The measured parameters are the acoustic nautical area scattering coefficient (sA in m2 nmi-2 or NASC), an indicator of marine organisms' biomass, and the acoustic volume backscattering strength (Sv in dB re 1 m-1), an indicator of marine organisms' density. Following standard procedures, we provide calibrated data for studying the spatial and temporal variability of these parameters, with the aim of gaining a better understanding of the processes that shape the mesopelagic ecosystem in the Tropical Atlantic. Beyond their regional scope, these data can also support large-scale studies of pelagic ecosystem structure and variability, model validation, and biogeochemical coupling at basin to global scales. The data are available in the SEANOE repository, an open-access platform dedicated to marine science datasets.