Boat seineA boat seine and its fishing operations.
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|OverviewThe boat seines consists basically of a conical netting body, two relatively long wings and a bag. An important component for the capture efficiency of boat seines is the long ropes extending from the wings, which are used to encircle a large area. Many seine nets are very similar in design to trawl nets. Frequently, however, the wings are longer than on trawls. The groundrope is usually a fairly heavy rope weighted with lead rings or hanging lead ropes. The seine ropes are made from synthetic fibre ropes with a lead core or from a combination of ropes.Handling EquipmentIn medium and large sized vessels special rope hauling (a small but fast winch) and coiling machinery is installed on deck. The long ropes are often coiled in bins (on or below the deck) but on modern Seiners these are stored on large hydraulic reels. For hauling the net hydraulically operated power blocks are used. In smaller boats seine nets are manually operated.Vessel OverviewSeine net boats range in size from relatively small 10 m up to about 30 m in length.Fish OperationSeine netting as originally developed, included setting of an anchored dahn (marker) buoy from where a first one drag line was set, followed by one of the wing, the bagnet, the second wing and finally the second dragline when the boat comes back to the anchored buoy simultaneously. The whole gear is encircling a large area in more or less a triangular pattern. The net is back by the anchored boat, which is done by hauling the two drag lines simultaneously with the help of the winches, first relatively slowly and increasing to a larger hauling speed when the net is nearly closed. The use of an anchor is often referred to as Danish seining. Fish inside the ropes are frightened into the forward moving path of the seine net where they are subsequently overtaken by the net and captured. Another boat seine technique is similar, but is not using an anchor. Instead the boat is kept stationary during haul back with the propeller. This technique is often referred to as Scottish seining or Fly dragging.Target SpeciesMainly demersal but to a lesser extent also pelagic species.Water Area OverviewAll over the world.Gear EnvironmentSeine nets are operated both in inland and in marine waters. The catching area depends on the length of the ropes; catching depth is shallower than 50 m in lakes and down till 500 m in marine waters. The techniques is most efficient on flat and smooth bottom when long ropes (2 500 m) can be used. Boat seines are also used in rougher grounds, but then with shorter ropes. In some areas are boat seines used to catch schooling fish off the bottom.ImpactsSpecies The impact on living resources are similar to that for trawls as small meshes in the codend may result in capture of undersized fish and sometimes non-target species.|