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Otter trawling derives its name from the large rectangular otter boards which are used to keep the mouth of the trawl net open. Otter boards are made of timber or steel and are positioned in such a way that the hydrodynamic forces, acting on them when the net is towed along the seabed, push them outwards and prevent the mouth of the net from ...
The otter may have multiple different designs. Otter boards used in bottom trawling are based on a similar design principle. The design takes advantage of the shearing effect achieved when the board is positioned at an oblique angle to the current. The effect is reminiscent of that of a kite in the wind.
However, single-boat trawling is more common. Here, the horizontal spread of the net is provided by trawl doors (also known as "otter boards"). Trawl doors are available in various sizes and shapes and may be specialized to keep in contact with the sea bottom (bottom trawling) or to remain elevated in the water. In all cases, doors essentially ...
After various unsuccessful dives and spotting signs of bottom trawling on the seafloor, they feared that it might have been destroyed altogether. Then, they discovered it: a rich marine animal ...
Trawling is a method of fishing that involves actively dragging or pulling a trawl through the water behind one or more trawlers. Trawls are fishing nets that are pulled along the bottom of the sea or in midwater at a specified depth. A trawler may also operate two or more trawl nets simultaneously (double-rig and multi-rig).
Otter trawl – An otter trawl is a demersal trawl which uses large rectangular otter boards to keep the opening of the trawl net from closing. Otter trawls are towed by a single trawler. Overfishing – occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans.
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1: trawl warp, 2: otter boards, 3: longline chains, 4 hunter, 5: weights 6: headline with floats, 7: pre-net, 8: tunnel and belly, 9: codend. Midwater trawling is trawling, or net fishing, at a depth that is higher in the water column than the bottom of the ocean. It is contrasted with bottom trawling.