Depth-integrated euphausiid (Family Euphausiidae) backscatter summary from echo integration-trawl survey of walleye pollock (Theragra chalcogramma) on the U.S. and Russian Bering Sea shelf in June, July, and August 2010

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Metadata:

Identification_Information
Data_Quality_Information
Spatial_Data_Organization_Information
Entity_and_Attribute_Information
Distribution_Information
Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: Ressler, Patrick H.
Originator:: Midwater Assessment Program (MACE) of the Resource Assessment and Conservation Engineering Division (RACE) of the NOAA National Marine Fisheries Service Alaska Fisheries Science Center (AFSC)
Publication_Date: Unpublished material
Title:: Depth-integrated euphausiid (Family Euphausiidae) backscatter summary from echo integration-trawl survey of walleye pollock (Theragra chalcogramma) on the U.S. and Russian Bering Sea shelf in June, July, and August 2010
Geospatial_Data_Presentation_Form: digital

Description:

Abstract:: Midwater walleye pollock biomass is measured during annual or biennial acoustic-trawl surveys conducted by the Midwater Assessment and Conservation Engineering (MACE) Program, Resource Assessment and Conservation Engineering (RACE) Division, of the NOAA-NMFS Alaska Fisheries Science Center (AFSC). Acoustic backscatter from euphausiids (Family Euphausiidae, principally Thysanoessa inermis and T. raschii) is now also measured during these surveys. In 2010, the acoustic-trawl survey was conducted from 5 June to 7 August using the NOAA Ship Oscar Dyson. Acoustic backscatter at five acoustic frequencies (18, 38, 70, 120, and 200 kHz) was measured along north-south survey transects spaced at an east-west distance of 20 nautical miles (nmi); backscatter from euphausiids was classified by comparing the observed frequency response, characterized by pairwise frequency differences between 18, 38, 120, and 200 kHz, to a reference library of known catch composition and frequency response derived from previous surveys. Methot trawling was used to determine the species and length frequency composition of detected euphausiid aggregations; analyses of these catch composition data are still in preparation. The summary data set submitted here includes the nautical area scattering coefficient (sA, m2 nmi-2) for euphausiids between 16 m below the sea surface and 0.5 m above the seafloor in 0.5 nmi intervals (averaging distance along the survey transect). The latitude, longitude, and vessel log distance values represent the starting location for each interval along the transect. sA is proportional to biomass of euphausiids, but these data have not yet been scaled to biomass units. The multifrequency classification method is described further in De Robertis et al. (2010) and Ressler et al. (accepted). Further information and detail on the midwater pollock survey data can be found by consulting Honkelehto et al. (in prep.) or by contacting the author of this data set.
Purpose:: The purpose of the submitted data set is to provide a spatially explicit estimate of euphausiid backscatter for use according to the BEST-BSIERP data policy. Those with a need for more detail should contact the Author of the data set. These data come from a regular stock assessment survey of midwater walleye pollock in the eastern Bering Sea. The purpose is to characterize the abundance and distribution of euphausiids, and important prey of walleye pollock. The digital data file described here was created for submission to the BEST-BSIERP program database.
Supplemental_Information:: This data set as submitted to the database is unpublished. Use and citation of these data must conform to the BEST-BSIERP data policy (<http://www.eol.ucar.edu/projects/best/program_management_plan.pdf>) and standard scientific practice.
A manuscript describing these data by Ressler et al. was recently accepted to the journal Deep-Sea Research II:
Ressler, P.H., De Robertis, A., Warren, J.D., Smith, J.N., Kotwicki, S. Using an acoustic index of euphausiid abundance to understand trophic interactions in the Bering Sea ecosystem. Accepted, Deep-Sea Res. II
The following is a publication that describes the frequency classification method used:
De Robertis, A., D.R. McKelvey, and P.H. Ressler. 2010. Development and application of empirical multifrequency methods for backscatter classification in the North Pacific. Can. J. Fish. Aquat. Sci. 67: 1459–1474. The following is a publication about the data that describes the 2010 acoustic trawl survey:
Honkalehto, T., A. McCarthy, P. Ressler, K.Williams, and D. Jones. In preparation.
Results of the acoustic-trawl survey of walleye pollock (Theragra chalcogramma) on the U.S. and Russian Bering Sea shelf in June - August 2010 (DY1006). AFSC Processed Rep. xxxx, xx p. Alaska Fish. Sci. Cent., NOAA, Natl. Mar. Fish. Serv., 7600 Sand Point Way NE, Seattle WA 98115.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 20100605
Ending_Date: 20100807

Currentness_Reference: Start and end dates of the survey

Status:

Progress: Complete
Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Description_of_Geographic_Extent: Eastern Bering Sea Shelf

Bounding_Coordinates:

West_Bounding_Coordinate: -180.0
East_Bounding_Coordinate: -160.0
North_Bounding_Coordinate: 63.0
South_Bounding_Coordinate: 54.0

Keywords:

Theme:

Theme_Keyword_Thesaurus: None
Theme_Keyword: project_number:B62
Theme_Keyword: data_url:<http://data.eol.ucar.edu/codiac/dss/id=245.B62-005>
Theme_Keyword: archive_url:<http://www.eol.ucar.edu/projects/bsierp>

Place:

Place_Keyword_Thesaurus: None
Place_Keyword: Bering Sea
Place_Keyword: Alaska
Place_Keyword: AK

Taxonomy:

Keywords/Taxon:

Taxonomic_Keyword_Thesaurus: None
Taxonomic_Keywords: Euphausiids
Taxonomic_Keywords: Euphausiidae
Taxonomic_Keywords: Thysanoessa raschii
Taxonomic_Keywords: Thysanoessa inermis