2018 Summer California Current Ecosystem CPS Survey (RL1807, EK80). In the California Current Ecosystem (CCE), multiple coastal pelagic fish species (CPS), including Pacific sardine (Sardinops sagax), Northern anchovy (Engraulis mordax), jack mackerel (Trachurus symmetricus), Pacific mackerel (Scomber japonicus), and Pacific herring (Clupea pallasii), comprise the bulk of the forage fish assemblage. These populations of these species can change by an order of magnitude within a couple years, represent important prey for marine mammals, birds, and larger migratory fishes (Field et al., 2001), and are targets of commercial fisheries.

Between 26 June and 23 September 2018, an Acoustic-trawl method (ATM) survey was performed to sample the west coast of North America, from the northern tip of Vancouver Island, British Columbia to San Diego, CA to estimate the biomass distributions and abundances of CPS, krill, and their abiotic environments in the CCE. The ATM survey was part of a larger joint survey with the Southwest Fisheries Science Center Marine Mammal and Turtle Division that used line-transect sampling to estimate the abundances, distributions, and demographcis of marine mammals and seabirds within the sampling domain. Acoustic sampling and visual observations of marine mammals and seabirds were conducted along 127 east-west acoustic transects totaling 6104 nmi. To estimate the proportions of coastal pelagic species and their lengths, catches were analyzed from 169 trawls.

On the NOAA Ship Reuben Lasker, multi-frequency (18, 38, 70, 120, 200, and 333 kHz) EK60 General Purpose Transceivers (GPT, Simrad) and EK80 Wideband Transceivers (WBT, Simrad) were configured with split-beam transducers (Models ES18-11, ES38B, ES70-7C, ES120-7C, ES200-7C, and ES333-7C; Simrad) mounted on the bottom of a retractable keel or “centerboard”. The keel was retracted (transducers ~5-m depth) during calibration, and extended to the intermediate position (transducers ~7-m depth) during the survey. Exceptions were made during shallow water operations, when the keel was retracted; or during times of heavy weather, when the keel was extended (transducers ~9-m depth) to provide extra stability and reduce the effect of weather-generated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), MS70 multibeam sonar (Simrad), and SX90 omni-directional sonar (Simrad). Transducer position and motion were measured at 5 Hz using an inertial motion unit (POS-MV, Trimble/Applanix).

Final 2018 Report: https://repository.library.noaa.gov/view/noaa/19759 Final 2018 Biomass Report: https://repository.library.noaa.gov/view/noaa/19853