Mobile fauna data were collected using the Tethered Optical Assessment Device (TOAD), a sled equipped with underwater video camera 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, usually between 1800 and midnight. The TOAD was deployed from a pot hauler mounted on the starboard side of the fantail on NOAA Ship Townsend Cromwell. It was lowered slowly to the bottom by the deck crew with the use of a capstan. The TOAD operator monitored a live video feed from the camera and began recording data on two video tape recorders. When the camera reached bottom the deck crew was notified by radio to stop lowering. The TOAD was a MiniBat 8820 unit manufactured by Guideline, and was towed by the ship at 1-2 knots while remotely guided from the ship using adjustable wing controls to keep the unit close to the underwater substrate. The TOAD was damaged during the cruise on 02/20/02, and subsequent tows were conducted as drift deployments. At each station the ship was positioned with the wind on the starboard side and drifted downwind; occasional light turns were applied to the ship's screws if necessary to reduce the ship's motion. The operator continued to monitor the vehicle and provided commands to raise or lower it to keep the camera just above the bottom.
Equipment Description: The TOAD is a camera sled based on the Guildline MiniBat model 8820 tow body. The frame was configured with a single Sony DCR-PC110 Digital Video Camera in a modified Gates underwater housing and two 500 W DeepSea Power & Light model 710-0400601 underwater lights. The MiniBat pressure sensor and wing controller were also mounted on the frame but the pressure sensor was not operational. After damage to the TOAD on 02/20/02and the sled's wings were not installed thereafter. The cable between the sled and the surface was an underwater load-bearing electrical cable. The TOAD computers were located in the Electronics Lab of the Townsend Cromwell. The electronics box containing the power switches was secured to the ship's fantail, and all other TOAD surface components were secured in the ship's wet lab.
Name & address of person collecting data: John Rooney NOAA PIFSC 1125B Ala Moana Blvd
Data Files: Video data were recorded on two video tape recorders. The position of the camera sled was recorded using Guildline MiniBat In-Tow data acquisition software.
File naming convention: Each tow is given a name consisting of a 3-letter designator for the island area, "LAY" in this case followed by a five-digit tow number. The first two digits indicate the last two digits of the calendar year, i.e., "02" is used for this cruise, which took place in 2002. The last three numbers indicate the consecutive number of the tow for that island and year, and start on the next hundred for subsequent cruises in that year to the same island. During TC0207 the consecutive numbers started at 020. Video tape labels, the navigation files (*.glo) and paper log forms are all annotated with the tow name. Metadata were extracted from the navigation data and recorded to a file with the same name as the navigation file except that a file type of ".met" was appended; for example, "LAY02002.glo.met"
Time Correlation: All times are based on UTC. Two clocks were set manually synchronized prior to starting data collection; the clock in the video character generator that was used to annotate the video tape and the TOAD data acquisition computer clock was used to annotate the navigation (*.glo) files. These clocks were set to UTC at the beginning of each evening's operations and then compared to one another prior to (and during) each tow. There were problems maintaining synchronization of the TOAD computer clock during this cruise. See the problems section for a description.
Resource Description: Digital video images geo-referenced to navigation files
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), 20090930, CRED Fish Biomass Estimates at Laysan Island, 2002.Online Links:
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in Decimal Degrees.
The horizontal datum used is D_WGS_1984.
The ellipsoid used is WGS_1984.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257224.
Benthic Habitat Mapping Group, Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Oceanic and Atmospheric Administration (NOAA)
(808) 983-3776 (voice)
(808) 983-2902 (FAX)
pibhmc@soest.hawaii.edu
These data will provide optical observations that will be correlated with bathymetry and acoustic backscatter imagery to create a fish biomass map of Laysan Island. Refer to supplemental information for description of instrument and survey.
The horizontal position accuracy for the camera sled position is 100 meters. There are three 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 used; no attempt is made to translocate this position to that of the tow block from which the camera is deployed. The difference between the tow block and the antenna is about 14 meters. The camera sled position is based a layback calculation that use ship's course, the amount of cable out and the camera sled depth to develop an estimate of the camera sled position. The amount of cable deployed is manually entered by the operator during a given camera tow.
Complete
Unspecified
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.
(808) 983-3776 (voice)
(808) 983-2902 (FAX)
pibhmc@soest.hawaii.edu
Downloadable Data
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.
| Data format: | Each comma-delimited record contains year, day of year, time, latitude longitude, velocity north and east, water column depth, vehicle depth, layback, and wing angle. For this dataset the fields for vehicle depth and wing angle do not contain useful data. List of navigation files: LAY02002.glo in format ASCII |
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| Network links: |
<http://www.soest.hawaii.edu/pibhmc/pibhmc_nwhi_lay_optical.htm> |
| Media you can order: |
CD-ROM
(format ISO 9660)
|
| Data format: | List of video tapes: LAY02002, VHS, Master LAY02002, Mini Dv, Master LAY02002, Mini Dv, Backup in format mini digital video and VHS |
|---|---|
| Media you can order: |
Video cassette tape
(format VHS, Mini DV)
|
(808) 983-3776 (voice)
(808) 983-2902 (FAX)
pibhmc@soest.hawaii.edu
