Surface Trawl Survey Acoustics (B59)

Surface Trawl Survey Acoustics (B59)

Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: Horne, John K.
Originator: Parker-Stetter, Sandra L.
Originator: Farley, Ed
Publication_Date: 20090804
Title: Surface Trawl Survey Acoustics (B59)
Geospatial_Data_Presentation_Form: spreadsheet
Publication_Information:
Publication_Place: Seattle.WA
Publisher: University of Washington
Description:
Abstract:
This project will quantify forage fish (e.g. juvenile pollock, capelin, herring) distributions on portions of the eastern Bering Sea shelf, and examine how oceanography and environment may influence forage fish distribution, abundance, and ultimately effect apex predator distribution and abundance. Acoustics and midwater trawling will be added to the BASIS survey (project B90) to document density distributions of forage species. We will map forage species distribution and compare distributions and abundances among survey years and supply IBM and energetic models with forage fish data as requested. Milestones for the reporting period are listed above.
Purpose:
These data provide acoustic backscatter estimates for YOY (or age-0) walleye pollock, YOY (or age-0) Pacific cod, jellyfish, and mixed forage species from the 2008 BASIS survey. They are intended to provide an index of relative distribution for BSIERP/BEST models. Users who wish to use the data for other purposes should contact the authors.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20080907
Ending_Date: 20080929
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Description_of_Geographic_Extent: Bering Sea shelf in water depths between 30 to 100 m.
Bounding_Coordinates:
West_Bounding_Coordinate: -169.00000
East_Bounding_Coordinate: -161.00000
North_Bounding_Coordinate: 59.50000
South_Bounding_Coordinate: 55.50000
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: BSIERP fish component
Theme_Keyword: B59
Theme:
Theme_Keyword_Thesaurus: IOOS Core Variables
Theme_Keyword: Version 1
Theme_Keyword: Fish abundance
Theme:
Theme_Keyword_Thesaurus: AOOS Data Services
Theme_Keyword: metadata=NPRB/BSIERP/B59_Horne.xml
Theme:
Theme_Keyword_Thesaurus: Alaska Marine Information System
Theme_Keyword: project_number:26
Theme_Keyword: data_url:<http://ak.aoos.org/data/bsierp/secure/B59/Horne/>
Theme_Keyword: archive_url:<http://ak.aoos.org/data/archive/2009/0000025/>
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: Bering Sea
Stratum:
Stratum_Keyword_Thesaurus: None
Stratum_Keyword: Bering Sea shelf, 30-100 m water depth
Temporal:
Temporal_Keyword_Thesaurus: None
Temporal_Keyword: September 2008
Taxonomy:
Keywords/Taxon:
Taxonomic_Keyword_Thesaurus: None
Taxonomic_Keywords: juvenile pollock
Taxonomic_Keywords: jellyfish
Taxonomic_Keywords: forage fish
Access_Constraints:
Access is restricted. Data policy: <http://bsierp.nprb.org/posted/proj_mgmt/Final%20NPRB-NSF%20program%20management%20plan%202007%2012_21.pdf>
Use_Constraints:
Use is restricted. Data policy: <http://bsierp.nprb.org/posted/proj_mgmt/Final%20NPRB-NSF%20program%20management%20plan%202007%2012_21.pdf>
Analytical_Tool:
Analytical_Tool_Description: none
Tool_Access_Information:
Tool_Access_Instructions:
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
These data are considered to represent conservative estimates of YOY pollock, YOY Pacific cod, surface jellyfish (dominated by Chrysaora), and deep jellyfish (dominated by Chrysaora). If the identity of a scattering group was not known (i.e., in the mixed region at night, containing jellyfish and mixed forage), the classification "forage sps + jellyfish" is used. Mixed forage species (herring, sandlance, rainbow smelt, capelin, Pacific cod, juvenlie rockfish, juvenile pollock), are also presented. No formal estimates of accuracy were performed given limited sampling but standard procedures were used throughout the analysis.
Logical_Consistency_Report: not applicable
Completeness_Report:
The following definitions or acronyms are used in these data: YOY pollock = young-of-the-year (i.e., age-0) walleye pollock YOY Pacific cod = young-of-the-year (i.e., age-0) Pacific cod Layer_jellyfish = generally small jellyfish, dominated by Chrysaora Deep_jellyfish = generally large jellyfish, dominated by Chrysaora Forage fish or Forage = a mixture of small forage-sized fish (herring, sandlance, rainbow smelt, capelin, YOY Pacific cod, YOY pollock) that could not be disriminated with available trawl samples
In the spreadsheet names: D = daytime only data N = nighttime only data D&N = data from both day and night combined
Column headers and additional notes are given in the "File Info" page of the Excel file.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report: none
Lineage:
Methodology:
Methodology_Type: Field
Methodology_Description:
Acoustic data contained in this dataset were collected with the 38 kHz Simrad EK60 unit on the RV Oscar Dyson .
Methodology:
Methodology_Type: Field
Methodology_Description:
The 2008 BASIS survey was conducted on the Bering Sea shelf (~30 m to 100 m depth ranges) between September 7 and 29 aboard the RV Oscar Dyson. Acoustic data (18, 38, 70, 120, and 200 kHz) were collected along transects between surface trawl stations. One midwater trawl was performed each day to identify targets observed on the acoustics. This dataset was analyzed using the 38 kHz acoustic data and midwater+surface trawl data for species or group assignment. Data are presented as integrated water column backscatter (i.e., acoustic energy summed over the water column) within 0.5 nmi horizontal bins for species or scattering groups. Species or group assignment was made only when adequate verification occurred with midwater or surface trawls and patterns on the acoustics could be matched with species or group composition. When composition was uncertain, data comments will assist with interpretation. Data are from both day (D) and night (N) periods, but are either combined D&N or kept separate (D or N) in spreadsheets depending on expected bias from combining them. These data are considered to represent conservative estimates of juvenile pollock, surface jellyfish, deep jellyfish, and mixed forage backscatter.
Process_Step:
Process_Description:
Noise (TVG-rampled) was removed from the data using traditional (linear subtraction) methods. A 10 dB signal-to-noise (SNR) ratio was imposed. All depths were held to a minimum Sv threshold of -95 dB (=-105 dB noise estimate at the deepest survey depth (90 m) + 10 dB SNR).
A 0.5 m backstep was used to exclude data from withon 0.5 m of the bottom. To account for transducer location (9.15 m from the surface) and saturation, data were excluded from the surface to 15 m depth.
Process_Date: Unknown
Process_Step:
Process_Description:
The bottom of the layer was defined using a edge-detection routine and smoothed by an operator.
Process_Date: Unknown
Process_Step:
Process_Description:
The layer (defined as the layer bottom and above) was partitioned into YOY fish (min Sv threshold = -67 dB, no max Sv threshold) and jellyfish (min Sv threshold = -95 dB, max Sv threshold = -67 dB). Based on the proportions of YOY pollock and YOY Pacific cod captured in trawls, YOY pollock were allocated 94.5% of the YOY fish backscatter and Pacific cod were allocated 5.5% of the YOY fish backscatter.
Process_Date: Unknown
Process_Step:
Process_Description:
Below the layer, in water with jellyfish scattering and verified with midwater trawling, we imposed a -95 dB Sv minimum threshold and grouped all backscatter into the "Deep_jellyfish" classification, acknowledging that it may contain some backscatter from small fish schools.
Process_Date: Unknown
Process_Step:
Process_Description:
In shallow water (generally <50 m deep, below the layer if one was present) wth fish schools or single targets we classified backscatter into jellyfish (minimum Sv threshold = -95 dB, maximum Sv threshold = -67 dB) and mixed forage fish (Sv minimum threshold = -67 dB, no maximum Sv threshold). Based on net catches, mixed forage fish could be herring, sandlance, rainbow smelt, capelin, YOY Pacific cod, or YOY pollock.
Process_Date: Unknown
Process_Step:
Process_Description:
All backscatter data (NASC=sA in units of m^2/nmi^2) were exported in 0.5 nmi horizontal bins for the entire water column (between 15 m depth and 0.5 m from the bottom).
Process_Date: Unknown
Process_Step:
Process_Description:
Updated metadata record for integration of dataset with Alaska Marine Information System. Original metadata filename: B59 metadata.xml. The new filename for AMIS: B59_Horne.xml
Process_Date: 20091020
Process_Step:
Process_Description: Edited metadata for consistency.
Process_Date: 20091213
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Point
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Geographic:
Latitude_Resolution: 0.0001
Longitude_Resolution: 0.0001
Geographic_Coordinate_Units: Decimal degrees
Geodetic_Model:
Ellipsoid_Name: World Geodetic System of 1984
Semi-major_Axis: 6378137
Denominator_of_Flattening_Ratio: 298.25722210088
Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
The dataset contains the following items. Column headers are listed in CAPITAL letters.
TRANSECT is the transect number 1-5 (going east to west)
INTERVAL is the analytic number for the horizontal bin (0.5 nmi) that referernces our dataset
DIEL indicates whether the data are from day or night
NASC is the acoustic backscatter (NASC=sA in units of m^2/nmi^2) integrated over the water column (15 m depth to 0.5 m above bottom) within the 0.5 nmi INTERVALs. This is the field that should be used for relative distribution
DATE is date (recalling that time is in GMT) at the middle of the INTERVAL
TIME is time (in GMT) at the middle of the INTERVAL
LAT_M is the geographic coordinate (decimal degrees) at the middle of the INTERVAL
LON_M is the corresponding geographic coordinate (decimal degrees) at the middle of the INTERVAL CLASSIFICATION contains species or group identification when possible.
COMMENT contains any additional comments to aid in the interpretation of the data
In the spreadsheet titles: D = daytime only data N = nighttime only data D&N = day and night data *if data are separated into D or N spreadsheets, they should be analyzed that way as we surmise tha a bias would be present in combining them. If data are listed in a single spreadsheet as D&N, we consider the bias from combining the diel periods to be minimal in this dataset.
Entity_and_Attribute_Detail_Citation: Spreadsheet explanation
Metadata_Reference_Information:
Metadata_Date: 20090723
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Sandra Parker-Stetter or John Horne
Contact_Organization: University of Washington
Contact_Address:
Address_Type: mailing
Address: UW-SAFS
Address: Box 355020
City: Seattle
State_or_Province: Wahington
Postal_Code: 98195-5020
Country: United States
Contact_Voice_Telephone: 206-221-5459 (SPS)
Contact_Voice_Telephone: 206-221-6890 (JH)
Contact_Electronic_Mail_Address: slps@u.washington.edu
Contact_Electronic_Mail_Address: jhorne@u.washington.edu
Metadata_Standard_Name:
FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001.1-1999
Generated by mp version 2.9.7 on Wed Jan 13 13:26:51 2010