Abstract:

Patterns in acoustically-derived biological scatter through the water column were collected with multi-frequency scientific echosounders (Simrad EK80) operating at 18kHz, 38kHz, 70kHz, and 120kHz following protocols developed during the NOAA NRDA DAP data collection operations. Specifically, transducers were installed on a rigid pole mounted to the side of the ship and calibrated at sea for operating conditions following protocols developed by Dr. Kevin Boswell during the ONSAP/DAP cruises. The dynamics of the mesopelagic scattering community will be examined through the depth- dependent scattering responses at the 18 and 38 kHz frequencies, as well as through the difference between the mean volume backscattering strength (MVBS; in dB) at 18 kHz and 38 kHz (dMVBS(18-38)). In addition, scatterers in the upper water column (~150m) will be examined by analyzing all four available frequencies. Data were collected aboard the R/V Point Sur PS23_22 (DP09) in the northern Gulf of Mexico from 2023-05-02 to 2023-05-12. This dataset is a result of research funded by the National Oceanic and Atmospheric Administration's RESTORE Science Program (ROR - https://ror.org/0042xzm63) under award #NA19NOS4510193 to Nova Southeastern University.