Pelagic Trawling Figures


CSH-5 sonar display

Figure 2.4.1. The display of the Furuno CSH-5 Omni-directional Sonar shows a horizontal (above) and vertical (below) image of a herring school. In the horizontal view, the bottom is displayed as the circular ring along the edge of the 200 m search radius. The vertical display shows herring to be aggregated primarily in the 50-100 m portion of the water column.

midwater tow path

Figure 2.5.1.Towpath (time vs. depth) for a midwater deployment. Red lines denote depths of the headrope and footrope. Tow performance measurements for the High Speed Midwater Rope Trawl were obtained from the Simrad ITI and FS903 systems, and Vemco MiniLog temperature depth probes attached to the headrope and footrope.

high speed midwater rope trawl

Figure 2.5.2 Diagram of the High Speed Midwater Rope Trawl (HSMRT).

high speed midwater rope trawl gear

Figure 2.5.3 Bridle configuration and associated hardware for optimal fishing performance of the High Speed Midwater Rope Trawl. Trawl gear include: 1.8 m2 Suberkrub type doors, 273 kg tomweights, 1.5 m setback given the specifications in the figure, and tow speeds ranging 4.0-4.5 knots.