| 摘要 |
A bottom trawl (1) for fish catching comprising a trawl net having a front part and a cod-end part, and including such components usually present in a standard bottom trawl, is used in combination with an acoustic emitter (2) for producing an acoustic zone in front of the trawl net entrance. The emitter comprises transducer means mounted on the front end of a carrier towed by the trawl, and activating equipment located inside a sealed section of the carrier. The transducer means is adapted to produce a sector shaped acoustic directional zone (5, 6) oriented substantially horizontally in the direction of the trawl movement, the acoustic emitter being adjustable to set the angle of orientation of the transducer means such that an optimum level of acoustic pressure is achieved in the lower portion of said acoustic directional zone above the lop line of the trawl net. |
