EK60 Water Column Sonar Data Collected During OES0703L1

Oceanographic Survey of Cross Seamount and Control Sites (OES0703L1, EK60). The goals of the cruise were to collect acoustic backscatter and oceanographic data at Cross Seamount (18°43.285’ N, longitude 158° 15.710’ W), with an approximately 400 m deep plateau, and at control sites in the surrounding environment. Data collected consisted of CTD casts, trawl samples, and continuous monitoring of currents and biological acoustic backscatter. CTD cats were conducted at predetermined stations. CTDs were equipped with oxygen sensors and fluorometers, and water was sampled at discrete depths during each cast for chloropigment determinations. Trawl operations were conducted at predetermined stations using a Cobb trawl at depths of the shallow (nighttime) and deep (day and nighttime) sound scattering layers. Currents were continuously monitored using a RD Instruments Acoustic Doppler Current Profiler (ADCP) operating at 75 kHz frequency. Biological backscatter were recorded using the EK60 echosounder system (38, and 120 kHz) along predetermined transects.