EK80 Water Column Sonar Data Collected During GU2203

Summary of Objectives 1. Primary Objectives a. Assess the occurrence, abundance and geographical distribution of the early life stages of fall spawning fishes, especially king and Spanish mackerel, red drum, and snappers, on U.S. continental shelf waters in the GOM using a 61 cm bongo frame fitted with 0.335 mm nets, and a 1x2 m neuston frame fitted with a 0.950 mm net at selected Southeast Area Monitoring and Assessment Program (SEAMAP) stations in support of annual stock assessments. b. Describe the pelagic habitat of fish larvae through measurements of various physical and biological parameters: i. Record profiles through the water column of temperature, salinity, fluorescence, dissolved oxygen, and turbidity using a CTD at SEAMAP stations. ii. Measure chlorophyll a in replicate water samples taken at surface, maximum chlorophyll layer and near bottom (to a maximum of 200 m) depths using bench top fluorometry. iii. Detect and measure frontal features along the survey cruise track using data from the ship’s Fluoro-thermosalinograph flow-through system (TSG). c. Map the distribution of fish eggs and invertebrate zooplankton along the cruise track using a Continuous Underway Fish Egg Sampler (CUFES). d. Measure the vertical distribution of fish larvae by sampling at discrete depths in the water column at selected locations along the SEAMAP plankton survey grid using a 1 m Multiple Opening/Closing Net and Environmental Sensing System (MOCNESS) during both legs of the survey. 2 Template Date: 25SEP2020 e. Collect detailed observations of net-caught jellyfish and ctenophores. 2. Secondary Objectives a. Assess the occurrence and abundance of marine debris and microplastics in the GOM in collaboration with the NOAA Marine Debris Program. b. Collect zooplankton samples for a University of Florida graduate student project examining temporal stability of the isotopic baseline across the Gulf of Mexico.