Soundscape and Franciscana. San Clemente, Argentina, September 2025.

Audio files recorded in the Somborombón bay, near San Clemente del Tuyu, about 200 km SE of Buenos Aires, Argentina, from Sep, 9th, 2025 to Sep, 15th 2025 (UTC). GPS position is ( -36,249977° ; -56,868041°). Two instruments were installed. One is QHB Recorder from Smiot, Université de Toulon, set with sample rate of 512 KHz, sampling depth of 24 bits, two channels with two C57 hydrophones from Cetacean Research (UTC). This instrument was set on the ground at 3 m depth. The other is a Soundtrap ST 300 HF (Ocean Instruments), set with a sample rate of 576 KHz, 16 bits, one channel, fixed on the same structure (local hour = UTC -3h). Here we present a subset of the total dataset, with the four files, for each instrument, with most dolphins clicks (Narrow Band High Frequency). The visual follow up shows that the cetaceans are Franciscana (Pontoporia blainvillei).