Raw acoustic scattering data of organisms from the water column, cruise DP04 (R/V Point Sur cruise PS17-03), 2016-08-06 - 2016-08-19

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. Boswell during the ONSAP/DAP cruises. The dynamics of the mesopelagic scattering community were examined through the depth dependent scattering responses at both frequencies (18 and 38kHz) 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) were examined by analyzing the all four available frequencies. By integrating both methods, the magnitude of biological scattering at discrete-depth intervals was classified into major taxonomic components (e.g., fluid-like crustaceans, swimbladdered fishes) based on resonant properties and behavior. Data were collected aboard the R/V Point Sur (cruise PS17-03, DEEPEND DP04, 2016-08-06 - 2016-08-19).