CRED Fish Biomass Estimates at French Frigate Shoals in the Northwestern Hawaiian Islands, 2008

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Frequently anticipated questions:


What does this data set describe?

Title:
CRED Fish Biomass Estimates at French Frigate Shoals in the Northwestern Hawaiian Islands, 2008
Abstract:
Fish biomass data were collected using a Towed Optical Assessment Device (TOAD), an underwater sled equipped with an underwater digital video camera and lights. Data were collected at the Northwestern Hawaiian Islands, French Frigate Shoals to support Benthic Habitat Mapping efforts.
Supplemental_Information:
French Frigate Shoals is a large open atoll located at 23.75N, 166.2W. The underlying basalt structure is estimated to be 13.8 million years old. Tern Island is the largest island at FFS and was enlarged by the U.S. Navy just prior to World War II; numerous other small islets exist. The total land mass is only 0.23 sq. km but the large reef and adjacent banks include 733 sq. km of coral habitat less than 100 m.

Mobile fauna data were collected using the Tethered Optical Assessment Device (TOAD), a sled equipped with underwater video cameras and lights. These data are used to provide fish count and biomass maps where benthic habitat classification has been completed. Camera sled deployments were conducted at night and during the day. The camera sled was deployed off the starboard J-frame on NOAA ship Hi'ialakai. The TOAD was lowered slowly to the bottom by a winch holding 360 m of cable and operated from a control station in the dry lab of the ship. The TOAD operator monitored a live video feed from the camera and record data on a video tape recorder.

Equipment Description - The TOAD sled body used for the data collection is constructed from a shortened Phantom ROV body with a tail piece added for stability. The frame has been extensively modified from its original configuration and was equipped with two Deep Sea Power and Light Multi SeaCam 2060 color video cameras. One camera is mounted to point at approximately a 45 degree angle toward the seafloor and is the primary data collection instrument. The second camera is aimed straight ahead and the signal from this camera is fed to a second video monitor to provide warning of underwater obstructions. The video signals from the sled are sent via coaxial conductors within a 360 m long and 19 mm diameter umbilical cable to a topside control unit. The cable between the sled and the surface includes an internal strength member to support the sled frame. The cable is paid out and recovered using a dedicated custom-built winch equipped with slip rings and powered by a 5 hp electric motor. The winch is controlled at the winch itself for sled deployments and recoveries. The rest of the time a remote controller located in the dry lab is used to enable the operator at the video console to adjust the sleds altitude. All TOAD surface components are located in the Dry Lab in an equipment rack on the after bulkhead. Illumination is provided by two 250 W DeepSea Power & Light Multi-SeaLite model 1050 underwater lights mounted on the sled frame. The lights are located on each side of the sled to provide the maximum possible horizontal distance from the camera. An ORE Offshore model 4330B Multibeacon is attached to the sled to provide a response to acoustic interrogations sent by the Hi'ialakai's Model 4410D-01 Trackpoint II Plus Ultrashort Baseline acoustic tracking system.

The sled is also equipped with a sonar altimeter to detect the height of the camera above the seafloor, a pair of parallel lasers to determine the size/scale of viewed objects, a compass to determine the sled heading and orientation, and a depth (pressure) sensor. Neither the altimeter nor the pressure transducer functioned reliably during this cruise.

Name and address of person collecting data - John Rooney NOAA IRC NMFS/PIFSC/CRED 1845 WASP Blvd., Building 176 Honolulu, HI 96818

Data Files - Video data are recorded on a mini DV video tape recorder. The position of the camera sled is recorded using Hypack Max version 6.2b survey software.

File naming convention - Each tow is given a name consisting of a 3-letter designator for the island area followed by two-digit year and three-digit tow number. For example, during HI0804 (NOAA Ship Hi'ialakai's 4th cruise in calendar year 2008) the first tow was called FFS08001. Video tape labels and paper log forms are annotated with the tow name.

Data files recorded in Hypack software followed their CHS filename format consisting of the year, the first two letters of the platform name, the Julian date, and the hour and minute in which the file was started. For example, a file collected on July 18, 2005 (Julian date 199) aboard the Hi'ialakai starting at time 1935 would be 2005HI1991935.

Time Correlation - All times are based on UTC. Four clocks were manually synchronized prior to starting data collection; the clock in the on screen display that was used to annotate the video tape, in one of the video cassette recorders, in the Trackpoint II system, and in the computer running the Hypack Max software. These clocks are set to UTC at the beginning of each operation.

Resource Description: Digital video imagery that is geo-referenced to navigation files.

  1. How should this data set be cited?

    Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), 200906, CRED Fish Biomass Estimates at French Frigate Shoals in the Northwestern Hawaiian Islands, 2008.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -166.37545
    East_Bounding_Coordinate: -166.24015
    North_Bounding_Coordinate: 23.9084387
    South_Bounding_Coordinate: 23.6143596

  3. What does it look like?

    <http://www.soest.hawaii.edu/pibhmc/NWHI_images/FFS_TOAD_MF_445.jpg> (JPEG)
    French Frigate Shoals, NWHI - TOAD Tows and Multibeam Bathymetry

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 07-May-2008
    Ending_Date: 26-May-2008
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: Video imagery, track line navigation files, and log sheets

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

    2. What coordinate system is used to represent geographic features?

  7. How does the data set describe geographic features?


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Pacific Islands Benthic Habitat Mapping Center, Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), NOAA

  3. To whom should users address questions about the data?

    Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
    Attn: John Rooney
    NOAA IRC
    Honolulu, HI 96818

    808 725-5360 (voice)
    808 725-5429 (FAX)
    nmfs.pic.credinfo@noaa.gov

    Contact_Instructions: e-mail preferred


Why was the data set created?

These data will provide optical observations that will be correlated with bathymetry and acoustic backscatter imagery to create a fish biomass map of French Frigate Shoals. Refer to supplemental information for description of instrument and survey.


How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 16-Jul-2008 (process 1 of 1)
    After a tow is completed the video tape data is reviewed by spot-checking the master and backup tape to verify that data were recorded. Raw data files recorded using Hypack Max software include time, horizontal position, and ship's heading information are copied from the acquisition computer to the data archive. Tow-specific metadata are recorded in the data archive in the same location as the raw data, in a spreadsheet that was then referred to in creating metadata records of each island where data were collected during the cruise. Raw data files are exported as comma-delimited text files which were then imported into ArcGIS v9.2 and saved as shapefiles. TOAD video were classified for benthic habitat type to create Optical Validation maps to interpret acoustically derived data layers. These classified points were imported into a Microsoft Access 2003 database. All fish present during 15 second intervals before and after these positions were recorded and identified. Using LW coefficients derived from fishbase.org and size estimates from video, total biomass was calculated for a given point. An area of 0.0012 hectares per point observation was assumed based on average distances traveled between points as well as average width of field of view. A table with position, island, biomass(tonnes/hectare), and number of fish was exported from MS Access into ArcGis v9.3. This file was exported as a shapefile. A column with biomass data was symbolized using layer file MF_Biomass.lyr to create Fish Biomass Estimates map.

  3. What similar or related data should the user be aware of?


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    The horizontal position accuracy for the camera sled position is estimated at plus or minus +/- 20 meters. There are two primary sources of this error. The ship's positioning is based on GPS SPS, often called standalone or non-differential GPS positioning. SPS has a measured accuracy of under 5 meters. The position of the GPS antenna is referenced to the ship's granite block. The second and larger primary source of error is uncertainty associated with the sled's position as reported by the Trackpoint II acoustic tracking system, which is also referenced to the granite block.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Complete

  5. How consistent are the relationships among the observations, including topology?

    Unspecified


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints:
Please acknowledge the NOAA Coral Reef Ecosystem Division, Pacific Islands Fisheries Science Center as the source of this information.

  1. Who distributes the data set? (Distributor 1 of 1)

    Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
    Attn: John Rooney
    NOAA IRC
    Honolulu, HI 96818

    808 725-5360 (voice)
    808 725-5429 (FAX)
    nmfs.pic.credinfo@noaa.gov

    Contact_Instructions: e-mail preferred
  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    These data are not to be used for navigational purposes. NOAA makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. NOAA cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 12-Mar-2014
Last Reviewed: 18-May-2009
Metadata author:
Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
Attn: CRED Data Management Team
NOAA IRC
Honolulu, HI 96818

808 725-5360 (voice)
808 725-5429 (FAX)
nmfs.pic.credinfo@noaa.gov

Contact_Instructions: e-mail preferred
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


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