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Gillnets and entangling nets
Gillnets and entangling nets
Source: Scott.Fish.Inf.Pamp. Fig.30, p.40

ISSCFG code: 07
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OverviewGillnets and entangling nets are strings of single, double or triple netting walls, vertical, near by the surface, in midwater on on the bottom, in which fish will gill, entangle or enmesh. Gillnets and entangling nets have floats on the upper line (headrope) and, in general, weights on the ground-line (footrope). Gillnets or entangling nets consist in single or, less commonly, double (both are known as "gillnets", strictly speaking) or triple netting (known as "trammel net") mounted together on the same frame ropes. Several types of nets may be combined in one gear (for example, combined gillnets-trammel nets). These nets can be used either alone or, as is more usual, in large numbers placed in line ('fleets' of nets). The gear can set, anchored to the bottom or left drifting, free or connected with the vessel.Accessory EquipmentSmall solid floats, usually made of plastic and spherical, cylindrical or egg-shaped, are attached to the headrope and weights are evenly distributed along the footrope.Handling EquipmentGillnets (any type) can be hauled by hand, at least from shallow or moderate depth, in small-scale fisheries (when the total length of net is not too large). However, the use of gillnet or net hauler is now very common; sometime a power block can also be used. The gillnets are, most of the time, folded on the deck, often within a delimited area or, in some cases, kept on net drums.Vessel Overview Gillnetters.Fish OperationThe means of capture is that the fish are gilled, entangled or enmeshed in the netting. Gillnetting and entangling are two different principles of catching: a fish being retained by its gills or the whole or part of the body of the fish being entangled, in the net webbing; one or the other may happen according to the slack of the netting on the frame ropes.Target SpeciesPelagic, demersal and benthic species.Water Area OverviewAll over the world.Gear EnvironmentAccording to their design, ballasting and buoyance, these nets may be used to fish near to the surface, in midwateror at the bottom, either in inland and sea waters.ImpactsSpecies Real gillnets, at least those with a single netting, are, in general, considered as having a high degree of selectivity, in terms of fish species, as well as size of the fish which directly depends on the size of the mesh. Incidental catch of a number of endangered species such as turtles, sharks, marine mammals or seabirds, in certain areas is a matter of growing concern. Researches are carried out aiming to a reduction of this risk; at the same time, International Plans of Action for the reduction of the incidental catch of sharks or the entanglement of seabird when operating gillnets, were agreed on. "Ghost fishing", when lost (or discarded) gillnets, or any piece of netting, drifting or somehow attached to the bottom, continue, somehow, is also a serious concern. The use of new material or mounting can now make that lost nets will not fish for too long or unlimited time. For the above mentioned reasons, the United Nations banned, in 1991, the use of large scale high seas driftnets over 2.5 kilometers long. From the point of view of environment, in general, it is also worth noting the low energy consumption for fishing with gillnets.
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