Pacific Ocean Perch - Mapping
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Klein 3000 sidescan sonar unit towed behind the research vessel to map bottom reflectivity. |
Multibeam sonar mounted to the side of the research vessel used to map the depth of the seafloor. |
Five study areas surrounding the Islands of Four Mountains were mapped in summer 2004 using towed sidescan sonar (Klein 3000; 100 kHz) and multibeam sonar (Simrad SM2000, 200 kHz) systems. These acoustic systems determine bottom depth and reflectivity (backscatter indicating bottom hardness/roughness). The processed acoustic data sets were used to construct mosaics of each study area. |
Reflectivity collected by the sidescan sonar system.
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Bathymetry collected with the multibeam sonar system of Samalga Island south site. Depth ranged from 120 m (red) to 140 m (blue).
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Camera sled towed along the seafloor to collect video used to classify fish habitats in the study areas.
During the summer of 2004 we collected underwater video using a towed camera sled (photo above). Different habitats were delineated from the underwater video (image below).
For example, at the Samalga Island South site three types of habitats were found:
- low relief sandy habitat
- low relief sandy-cobble habitat
- relatively high relief boulder and sand habitat
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