ME70 Water Column Sonar Data Collected During RL1703

During spring 2017, part of the west coast of the United States was surveyed using Lasker during the principal spawning seasons of sardine and anchovy. Since the central sub-population of anchovy inhabits southern and central California during the spring, the survey began off San Diego and progressed northward toward San Francisco. Transect positions, lengths, and spaces were adjusted according to the expected distribution of anchovy at the time of the survey. Compulsory transects were nearly perpendicular to the coast with nominal separations of 20 nmi; adaptive transects were placed between compulsory transects to reduce nominal separation to 10 nmi when the survey encountered putative CPS backscatter in echograms, high-density eggs in the CUFES (1 or 0.3 eggs min-1 for anchovy or sardine, respectively), or adults in trawls. After initiating adaptive acoustic sampling, the adaptive transect immediately south of the completed compulsory transect was sampled before proceeding northward along the next adaptive and compulsory transects. An adaptive cluster was defined as a minimum of five consecutive transects with 10-nmi spacing. The transect positions also covered much of the potential habitat of sardine at the time of the survey. The survey spanned an area from approximately San Diego to San Francisco, with 27 east-west transects totaling 1828 nmi, and 64 Nordic trawls. Multi-frequency (18, 38, 70, 120, 200, and 333 kHz) General Purpose Transceivers (Simrad EK60 GPTs) and Wideband Transceivers (Simrad EK80 WBTs) were configured with split-beam transducers (Simrad ES18-11, ES38B, ES70-7C, ES120-7C, ES200-7C, and ES333-7C, respectively). The transducers were mounted on the bottom of a retractable keel or “centerboard”. The keel was retracted (~ 5-m depth) during calibration, and extended to the intermediate position (~7-m depth) during the survey. Exceptions were made during shallow water operations, when the keel was retracted to ~ 5-m depth; or during times of heavy weather, when the keel was extended to ~9-m depth to provide extra stability and reduce the effect of weather-generated noise. In addition, acoustic data were also collected using an ME70 multibeam echosounder (Simrad) and MS70 multibeam sonar (Simrad). Final Spring 2017 Survey Report: https://repository.library.noaa.gov/view/noaa/15394 Final Spring 2017 Biomass Report: No biomass report created. The next available biomass report is the Summer 2017 CCE Survey.