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Driftnets
Driftnets
Source: FAO-Fish.Tech.Pap.222, Fig. 1, p. 40
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Characteristics
OverviewDriftnets consist of a string of gillnets kept more or less vertical by floats on the upper line (headrope) and weights on the lower line (groundrope) (sometimes the groundrope is without weights), drifting with the current, in general near the surface or in mid-water.Accessory EquipmentSmall solid floats, usually made of plastic or of cork are attached to the headrope and lead weights are evenly distributed along the groundrope. Commonly are the lead attached to the core of the groundrope.Handling EquipmentFor setting and hauling driftnets net haulers are usually employed. The drifter capstan on the forepart of the vessel is typical for driftnetters. In developing countries most nets are commonly hauled by hand.Vessel OverviewDrift netters.Fish OperationThese nets drift freely with the current connected to the operating vessel. The method of capture is by gilling and driftnets are highly size selective on the targeted species.Target SpeciesDriftnets are especially used to catch schooling pelagic species like herring, mackerel and sardines, but also for salmon and tuna and pelagic squid are captured with such gears.Water Area OverviewAll over the world.Gear EnvironmentDriftnets are kept near the surface, or a certain distance below it. They are especially employed in marine waters.ImpactsSpecies The principal negative environmental impact produced by this type of nets is related to the bycatch of non-target species like marine mammals, seabirds and to a minor extent turtles. In general gillnets are a fishing gears with a high degree of size selectivity for fish, efficiently regulated by the meshsize. It is also a gear with low energy consumption calculated on the relationship of fuel/fish. Various instruments are developed to reduce the negative impact of drift netting on the non-targeted biological resources. In 1991, the United Nations banned the use of large scale high seas driftnets over 2.5 kilometers long. Prior to the UN driftnet ban, these nets were of enormous proportions reaching lengths of 40 to 60 km. Despite the UN ban on large scale driftnets, serious concerns exist regarding ongoing violations.
 
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