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Metadata
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ID
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B-1-98-SC
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Abstract
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United States Geological Survey, Menlo Park, California.
Chief Scientist: Guy Cochrane. Seismic and Sidescan Sonar and
Video data (YoNav, Kleinsidescan, underwatercamera) of field
activity B-1-98-SC in Santa Barbara Coast and Channel Islands
from 06/14/1998 to 06/29/1998
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Organization
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United States Geological Survey, Menlo Park, California
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Project/Theme
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Nearshore Benthic Habitats Project
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National Plan
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Environment
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Chief Scientist
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Guy Cochrane
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Activity Type
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Seismic and Sidescan Sonar and Video
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Platform
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Ballena
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Area of Operation
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Santa Barbara Coast and Channel Islands
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Location map
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Bounding Coordinates
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34.40898
-119.69134 -118.83857
34.00000
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Dates
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06/14/1998 (JD 165) to 06/29/1998 (JD 180)
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Analog Materials
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list
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Index map
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Crew
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Guy Cochrane
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Chief Scientist, USGS Western Region
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Mike Boyle
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Electronic Technician, USGS Western Region
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Equipment Used
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YoNav
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Kleinsidescan
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underwatercamera
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Purpose
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Nearshore Benthic Habitats mapping
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Information to be Derived
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2048 samples were recorded per channel over a swath width of 400 m yielding a pixel size of 0.1 m of seafloor area for the side-scan data.
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Summary
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We used the R/V Ballena, owned by the Channel Islands National Marine
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Sanctuary, for our geophysical surveying. Combined sidescan-sonar imaging,
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seismic reflection profiling, and towed bottom camera work began on June 15
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after a day of mobilization, and ended June 26 with one day of demobilization.
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Data was collected in nearshore waters, here defined as 0 to 100 meters in
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depth. Two areas were surveyed in 1998, a 59 square km area north of Anacapa
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Island, and a 113 square km area surrounding the Big Sycamore Canyon Reserve, on
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the California coast, northwest of Pt. Dume. Approximately 6 hours of bottom
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video was recorded in each of the two areas for groundtruthing the sidescan.The
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geophysical surveying done in this and future years will be combined with
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existing population studies, sediment sampling, ROV, submersible, and bottom
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video camera observations to better understand benthic habitat - faunal
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relationships. Navigation Systems - The 1998 survey was navigated with a Leica
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Differential Global Positioning System (DGPS) which provided a ship position
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with accuracy of 1-5 m in DGPS mode. At times during the cruise differential
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signal was interrupted. In non-differential mode, the receiver provided a
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position with 30-50 m accuracy. A KVH Industries Inc. azimuth digital
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gyro-compass provided ship headings with 0.5 degree accuracy. Navigation data
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were recorded using Yo-Nav version 1.19 (Gann, 1992). The sidescan fish is
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towed approximately 20 m above the seafloor. The distance behind the ship of the
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fish was not known during this survey and must be estimated when the data is
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processed in order to produce the sidescan image mosaics. Sidescan Surveying
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System - A Klein 2000 sidescan system was used for geophysical surveying. The
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unit features 8 channels of processed data, 7 subsurface from the towfish (5
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sonar and 2 instrumentation) and 1 surface (external analog input). Two sonar
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channels each were devoted to 100 KHz and 500 KHz sidescan data and a fifth
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sonar channel was used for 4 KHz subbottom profiling. The resolution of the
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profiler data is approximately 0.15 m of sub-bottom thickness (penetration of
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tens of meters is typical in unconsolidated sediment). A Triton Elics Isis
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brand side-scan data recording system was used on the cruise. The Isis system
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simultaneously records 5 channels of data; port and starboard 100 KHz side-scan
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data, port and starboard 500 KHz side-scan data, and profiler data. Side-scan
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data shown in this report are 100 KHz data. Typically, 2048 samples were
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recorded per channel over a swath width of 400 m yielding a pixel size of 0.1 m
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of seafloor area for the side-scan data.
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Notes
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Associated cruises in southern California:
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B-1-98-SC
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B-1-99-SC
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B-2-99-SC
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M-1-99-SC
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M-1-00-SC
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J-1-02-SC
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M-1-02-SC
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M-1-03-SC
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S-5-04-SC
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June 26, 1998
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TIDBIT FROM THE CHANNEL ISLANDS
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This from Guy Cochrane, via phone mail from the R/V Ballena: "Shot 40 sq km of
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side-scan with the Klein system off the north side of Anacapa Island, working
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with Channel Islands Marine Sanctuary people and the National Marine Fisheries
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Service. We've also done a day and a half of bottom video using Hank's camera
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sled, so we have about two hours of video tape. We've had really great weather.
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Conditions have been perfect for both side-scan and bottom video. Mike Boyle and
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I are doing okay."
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July 10, 1998
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CHANNEL ISLANDS BENTHIC HABITATS CRUISE
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Mike Boyle and I finished the two-week Channel Islands/Santa Barbara benthic
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habitats cruise on Saturday, June 27, and off-loaded on Sunday, June 28. We
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sidescanned a 40-sq-km area of Anacapa Island and a 60-sq-km area on the coast
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south of Ventura. Both areas contain state fish reserve areas and are in the
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Channel Islands National Marine Sanctuary, or the National Park. We also have
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about 8 hours of bottom video from both areas, thanks to very cooperative
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weather. We did have some trouble with Differential GPS reception and will try
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to improve our system prior to returning to the area. Guy Cochrane
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Publications
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Cochrane, G.R., and Lafferty, K.D., 2000, Activities and Preliminary Results of Nearshore Benthic
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Habitat Mapping in Southern California, 1998, U.S. Geological Survey Open File Report 2000-321:
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http://pubs.er.usgs.gov/usgspubs/ofr/ofr00321
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Cochrane, G.R., Nasby, N.M., Reid, J.A., Waltenberger, B., and Lee, K.M., 2003, Nearshore
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Benthic Habitat GIS for the Channel Islands National Marine Sanctuary and Southern California State
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Fisheries Reserves Volume 1, U.S. Geological Survey Open File Report 2003-85:
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http://pubs.er.usgs.gov/usgspubs/ofr/ofr0385
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Got Help?
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For B-1-98-SC, we would appreciate any information on -- contract, days at sea, dive count, funding, information specialist, kms of navigation, NGDC Info, owner, ports, project number, scanned materials, seismic description, station count, station description, submersible, tabulated info.
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