2017 Spawning Hake Stock Acoustic-Trawl Survey SH1701, EK80)

The primary goals of the survey are to characterize the winter distribution of hake, the hake aggregations, and the fish within those aggregations in order to support an evaluation of the feasibility of a future winter hake biomass survey. The

project will use data from an integrated acoustic and trawl survey off the west coast of the U.S. from approximately south of San Diego, CA (latitude 31.6?N along the U.S. EEZ) to approximately Newport, OR (latitude 44.6?N). Our

objectives are to:

- Conduct 24-hour acoustic, trawl, oceanographic, and zooplankton operations.

- Continuously sample multi-frequency acoustic backscatter data using the ship?s Simrad EK60 scientific echosounders (18, 38, and 120 kHz) system. Simrad EK80 broadband echosounders will operate at 70 and 200

kHz. Collectively, the acoustic data will be used to characterize the distribution of hake and describe hake aggregations.

 -- Collect acoustic data along pre-planned diagonal transects along the coast (hereafter ?transects?).

 -- Collect acoustic data over hake aggregations, where the design will be determined based on the observed aggregation (hereafter ?adaptive transects?).

- Collect stationary acoustic data 1 hour before sunrise/sunset to 1 hour after sunrise/sunset to evaluate migration (vertical and/or horizontal) of hake aggregations.

- Conduct daytime and nighttime trawling (Appendices 3 and 4) to verify hake aggregations and obtain specimens for biological data (length, sex, maturity, age, ovaries, diet, genetics, etc.).

  -- Multiple trawl samples may be taken on a single hake aggregation to evaluate heterogeneity in sex, maturity, etc.

  -- Record data from shipboard net mensuration gear to evaluate trawl performance

- Use a portable x-ray system (Appendices 5 and 6) to take radiographic images of fish swimbladders

- Optically verify the presence of non-hake scatterers during trawling using a video camera and light(s) attached to the upper panel of the midwater trawl approximately 20-30 meters forward of the codend.

- Conduct vertical casts with the ship?s CTD rosette, outfitted with a dissolved oxygen sensor and Niskin bottles, at pre-planned stations along transects and/or at trawl locations (Appendix 2, Table 2, Table 4, and Table 5). These data will be used to describe the vertical and horizontal distributions of hake relative to oceanographic conditions. Niskin water

collections will be filtered for evaluation of environmental DNA (eDNA).

- Conduct underway CTD (uCTD) casts at pre-planned stations along transects (Appendix 2, Table 6). These data will be used to supplement oceanographic information obtained from the CTD rosettes and will be used to describe the distribution of hake relative to ocean conditions 

- Continuously collect Acoustic Doppler Current Profiler (ADCP) data along transects. These data will be used to describe the distribution of spawning hake relative to currents.

- Conduct vertical ring net zooplankton tows at pre-planned stations along transects (Appendix 1, Figure 1; stations are listed in Appendix 2, Table 2) and bongo net tows (Appendix 1, Figure 1; stations are listed in Appendix 2, Table 3). These data will be used to describe the winter distribution of zooplankton species.

- Continuously sample sea-surface temperature, salinity, and chlorophyll-a using the ship?s thermosalinograph and fluorometer. These data will be used to estimate the physical oceanographic habitats for spawning hake.

- Continuously sample air temperature, barometric pressure, and wind speed and direction using the ship?s integrated weather station.

- Collect broadband acoustic data with EK80 echosounders operating at central frequencies of 70 and 200 kHz. The use of the EK80s will require temporary modification to the ship?s EK60 set-up.

Tags: North Pacific Ocean, earth-science--biosphere--ecosystems--aquatic-ecosystems, earth-science--biosphere--ecosystems--marine-ecosystems, earth-science--biosphere--ecosystems--marine-ecosystems--benthic, earth-science--biosphere--ecosystems--marine-ecosystems--pelagic, earth-science--oceans--aquatic-sciences--fisheries, earth-science--oceans--bathymetryseafloor-topography--bathymetry, earth-science--oceans--bathymetryseafloor-topography--seafloor-topography, earth-science--oceans--ocean-acoustics--acoustic-scattering, geographic-region--global, nodc.noaa.gov, vertical-location--sea-floor
Organization: Ocean Data Partners