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EK80 Water Column Sonar Data Collected During RL1603

Metadata Updated: November 10, 2022

Multi-frequency (18-, 38-, 70-, 120-, 200-, and 333-kHz) General Purpose Transceivers (Simrad EK60 GPTs), 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 The keel was retracted (~ 5-m depth) during calibration, and extended to the intermediate position (~7-m depth) during the survey. Exceptions were made during shallow water operations, when the keel was retracted to ~ 5-m depth; or during times of heavy weather, when the keel was extended to ~9-m depth to provide extra stability and reduce the effect of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. Nighttime trawl sampling was conducted where echoes from CPS schools where observed earlier that day. Trawls were towed at ~ 4 kn for 45 min. The total catch from each trawl was weighed and sorted by species or groups. From the catches with CPS, up to 75 fish from each of the target species were selected randomly. Those were weighed (g) and measured to either their standard length (Ls; mm) for sardine, northern anchovy, and herring, or fork length (Lf ; mm) for jack mackerel and Pacific mackerel. Regional species composition was estimated from the nearest trawl cluster, i.e., the combined catches of up to three trawls per night, separated by ~ 10 nmi. During the day, fish eggs were collected using CUFES (Checkley et al., 1997), which collects water and plankton at a rate of ~640 l min-1 from an intake on the hull of the ship at ~ 3-m depth. The particles in the sampled water were sieved by a 505 μm mesh. All fish eggs were identified to lowest taxa, counted, and logged. Typically, the duration of each CUFES sample was 30 min, corresponding to a distance of 5 nmi at a speed of 10 kn. Because the initial stages of the egg phase is short for most fish species, the egg distributions inferred from CUFES indicate the nearby presence of actively spawning fish CalCOFI Bongo Oblique (CalBOBL, or bongo) nets (71-cm diameter; 505-μm mesh) were used to sample ichthyoplankton and krill at each station. Where there was adequate depth, 300 m of wire was deployed and then retrieved at 20 m min-1, at a nominal wire angle of 45. Paired vertical egg tow (Pairovet; formerly CalCOFI vertical egg tow or CalVET) (Smith et al., 1985) nets (25-cm diameter; 150-μm mesh) were used to sample fish eggs from a depth of 70 m to the sea surface at a rate of 70 m min-1 in areas where their densities exceeded a threshold of > 0.3 eggs min-1. Day and night, conductivity and temperature versus depth to 350 m were measured with calibrated sensors on a CTD probe cast. These data were used to estimate the time-averaged sound speed (Demer, 2004), for estimating ranges to the sound scatterers, and frequency-specific sound absorption coefficients, for compensating the echo signal for attenuation during propagation of the sound pulse from the transducer to the scatterer range and back (Simmonds and MacLennan, 2005). The CTD also provided indication of the depth of the upper-mixed layer, where most epipelagic CPS reside during the day. The survey comprised 16 east-west transects totaling 2623 nmi, and 43 Nordic trawls, which were used for acoustic-trawl biomass estimation. The survey spanned an area from approximately Newport, OR to north of Bodega Bay, CA. The concentration of adaptive samples off Oregon and damage to the trawl gear precluded sampling to the southern extent of the survey area.

Access & Use Information

License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Date October 14, 2022
Metadata Created Date November 10, 2022
Metadata Updated Date November 10, 2022
Reference Date(s) March 23, 2016 (creation), October 14, 2022 (publication)
Frequency Of Update notPlanned

Metadata Source

Harvested from NGDC MGG Sonar Water Column

Additional Metadata

Resource Type Series
Metadata Date October 14, 2022
Metadata Created Date November 10, 2022
Metadata Updated Date November 10, 2022
Reference Date(s) March 23, 2016 (creation), October 14, 2022 (publication)
Responsible Party NOAA National Centers for Environmental Information (Point of Contact)
Contact Email
Guid gov.noaa.ncei:RL1603_EK80
Access Constraints Cite as: NOAA Southwest Fisheries Science Center. 2022. EK80 Water Column Sonar Data Collected During RL1603. NOAA National Centers for Environmental Information. https://doi.org/10.25921/67a7-s312 [access date], Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives., Use liability: NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose., Resource may not be available for up to one year after initial collection.
Bbox East Long -118.15566
Bbox North Lat 44.95228
Bbox South Lat 33.37509
Bbox West Long -126.65438
Coupled Resource
Frequency Of Update notPlanned
Harvest Object Id 6d595065-4a93-407f-8f29-f77f49bf1e95
Harvest Source Id ab8b0290-e4db-4a00-89f2-4e427c2054b2
Harvest Source Title NGDC MGG Sonar Water Column
Licence These data are considered raw and have not been subjected to the NOAA's quality control or quality assurance procedures. They are released for limited public use as preliminary data to be used only with appropriate caution. NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty., Not subject to copyright protection within the United States.
Lineage Calibrated w/ calibration data
Metadata Language eng; USA
Metadata Type geospatial
Old Spatial {"type": "Polygon", "coordinates": [[[-126.65438, 33.37509], [-118.15566, 33.37509], [-118.15566, 44.95228], [-126.65438, 44.95228], [-126.65438, 33.37509]]]}
Progress completed
Spatial Data Service Type
Spatial Reference System urn:ogc:def:crs:EPSG::4326
Spatial Harvester True
Temporal Extent Begin 2016-03-23T00:00:00
Temporal Extent End 2016-04-23T11:59:59

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