| 摘要 |
A method of fishing the seabed for shellfish i.e. razor shells comprises towing a dredge 1 across the seabed by a vessel. The dredge comprises a forklike frame 2 attached to a flat carriage (4 figure 2) by the frame fork ends (2a figure 3, 2b figure 2) by means of a hinge joint (3 figure 2). The flat carriage (4 figure 2) comprises two wide parallel skids (7 figure 3) which may have a horizontal bearing surface for the dredge. At the front of the dredge there is an adjustable cutter 6 and a rectangular opening perpendicular to the direction of travel to take in the catch. The rectangular opening is provided with a ring line for compressed air which carries the catch of razor shells on a bed of fluidised air and water to the vessel deck via conduits 11 and 13. A short distance ahead of the skid (4 figure 2) a towing tackle is dragged by the vessel consisting of two welding cables (15 and 16 figures 3 and 4) each with a number of elongated electrodes (17 and 18 figures 3 and 4) connected at a mutual distance to each other perpendicular to the welding cables. The welding cables are connected to the towing tackle (19 figure 4) on a frame (20 figure 4) and fastening eye (21 figure 4) to which a towing cable (22 figure 4) is attached. A power generator onboard the vessel supplies an A.C. current/voltage to the cables as they are dragged across the seabed which irritates/numbs the shellfish causing them to move up out of the sand to lie on the seabed, where they are collected by the dredge. |
