Seine (fishing)
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Seine fishing is fishing using a seine. A seine is a large fishing net that hangs vertically in the water by attaching weights along the bottom edge and floats along the top. Boats equipped for seine fishing are called seiners.
Seine nets are usually long flat nets like a fence that are used to encircle a school of fish, with the boat driving around the fish in a circle.
There are two main types of seine nets: purse seines and Danish seines.
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[edit] Purse seine
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Purse seine |
A common type of seine is a purse seine, named such because along the bottom are a number of rings. A rope passes through all the rings, and when pulled, draws the rings close to one another, preventing the fish from "sounding", or swimming down to escape the net. This operation is similar to a traditional style purse, which has a drawstring.
The purse seine is a preferred technique for capturing fish species which school, or aggregate, close to the surface: such as sardines, mackerel, anchovies, herring, certain species of tuna (schooling); and salmon soon before they swim up rivers and streams to spawn (aggregation).
[edit] Danish seine
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Danish seine |
A Danish seine, also occasionally called an anchor seine, has a conical netting body, two relatively long wings and a bag. The drag lines extending from the wings are long, so they can encircle a large area.
A Danish seine is similar to a small trawl net, but the wire warps are much longer and there are no otter boards The seine boat drags the warps and the net in a circle around the fish. The motion of the warps herds the fish into the central net.
Danish seiner vessels are usually larger than purse seiners, though they are often accompanied by a smaller vessel. The drag lines are often coiled on the deck with the help of a coiling machine, or stored on drums. A brightly coloured buoy is anchored as the "marker" and serves as the fixed point for the hauling of the seine. A power block mounted on boom, or a deck crane with slewing, is used to handle the seine net.
Danish seining works best on demersal fish which are either scattered on or close to the bottom of th e sea, or are aggregated (schooling). They are used when there are areas with flat but rough seabeds which are not trawlable. It is especially usefulin northern regions, but not much in tropical and sub-tropical regions.
The net is set out from an anchored dan (marker) buoy. The operation is carried out directly by the main vessel, the "seiner", or from an additional smaller boat. First, one drag line is put into the water, then one net wing follows and, while the seiner turns round in a surrounding move, back to the buoy, the setting continue with the bag of the seine, then the other wing, then, finally, the other drag line. Thus a big area is encircled by the time the seiner returns to the anchored marker buoy or the smaller auxiliary boat used for the setting is back to the main unit. Next the net is hauled in with the two drag lines using rope-coiling machines by the boat anchored at the marker until the bag with the catch can be taken on board.
[edit] History
This fishing method evolved in Denmark and is the original seine netting technique from which "fly dragging" (Scottish seining) was a later development. The operation is much the same as fly dragging except the marker buoy is anchored while hauling, and the warps and net are closed entirely by winch.
[edit] See also
[edit] References
- Division of Commercial Fisheries (2005-07-26). Commercial Purse Seine Fishery. Alaska Department of Fish and Game. Retrieved on 2008-04-20.
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