|A purse seine is made of a long wall of netting framed with a lead line of equal or longer length than the float line.|
|American seiners are most common on both coasts of North America and in many areas of Oceana and like all purse seiners are a most effective vessels for catching aggregating species near the surface.
|Species EnvironmentFish are into large dense schools near the surface or aggregated by artificial means, such as floating object (Fish Aggregating Devices, FADs) or, at night, by light.Fishing GearA purse seine is made of a long wall of netting framed with floatline and leadline (usually, of equal or longer length than the former) and having purse rings hanging from the lower edge of the gear, through which runs a purse line made from steel wire or rope which allow the pursing of the net. For most of the situation, it is the most efficient gear for catching large and small pelagic species that is shoaling.Vessel Overview Purse seiners are the most important and most effective vessels to catch aggregating species near the surface. For pursing the seine, therefore hauling the purse line, a winch or a capstan is used. The purse line is either stored on the already mentioned winch: "purse seine winch" or kept separately on a purse line reel. In general large and/or modern purse seiners are equipped with purse seine winch while, small, more artisanal seiners may use the association: capstan plus purse line reel. On board large seiner, another capstan on foredeck can be used for hauling the tow line. Power block is used to transporting the nets on board the vessel, or back onto the wharf.Handling ModeThe modern distant waters purse seiners are equipped to freeze their catch.Fishery Production SystemsSemi-industrial and Industrial.Fishing EnvironmentMarine coastal and high-sea waters, between 0 and 300 m deep.Fishing OperationsThere are two different methods of purse seining: the one boat system and the two boats system. Both have their advantages and disadvantages, but purse seining with a single boat is now considered more economical, even though shooting a purse seine with the two boats system may be quicker and a larger gear can also be operated than with the one boat system. The American seiners is not much adapted to rough weather conditions compared to the European seiners. The high position of a heavy power block typical net hauling device used on the American seiners can itself cause problems of stability during fishing operations in rough waters.|
|1. Searching for fishFish schools can be detected near to the surface by visual observation (fish or seabirds flying over) from a crow's nest of in the vessel or by using echosounder and sonar.|
|2. Setting the netThe vessel moves ahead, drops skiff or buoy with net attached and moves in circular path paying out net over stern. It normally takes less than 5 minutes.|
|3. Completing the setThe vessel has completed the circle and is about to retrieve the buoy or skiff in order to take aboard the bridle and purse line.|
|4. Ready to purseThe extremities of the floatline and leadline are retrieved on board; each end of the purse line is taken to the purse winch and both ends pulled in together, starting the "pursing" of the bottom of the net.|
|5. Pursing proceedingThe bottom of the net is gradually being drawn tight.|
|6. Pursing completeThe purse rings have been pulled up and are hanging over the side of the boat. The bunt is secured forward so that the fish cannot leave the net.|
|7. Rings aboardRings aboard, web being hauled: the purse rings have been lifted aboard, they are fastened, then the purse line removed from the rings. The wing opposite to bunt side is passed through power block, and over one or two hours, the net webbing with both the floatline and leadline and, also rings is progressively hoisted in being taken aboard.|
Fishery AreaTemperate and tropical countries.IssuesEnvironmental Compared to most of the other fishing techniques, purse seining in general, is not harmful to natural resources or environment.Discard In certain cases, the potential negative impact produced by a purse seine may result from the fact that catching performance are not very selective (in terms of both species and sizes of fish): when there is important bycatch of non-targeted species or too many small fish. Incidental capture of dolphins by large tuna purse seiners fishing in certain high sea areas is regarded as an irresponsible fishing practise. Special techniques have been developed to reduce bycatch of dolphins; the Medina panel and "back down" operation, which secure that encircled dolphins are released alive. The increasingly used practice of encircling floating objects, including man-made FADs increases the capture of small sized and immature aggregating around such devices.Source of information
|8. Ready to remove fishThe net has been hauled until the fish are gathered in the bunt, close to the ships side. Brailing or pumping can now begin.|
Workshop on Gear and Vessel Technology. Dakar (Senegal), 10-15 Dec 1984. FAO. Fishery Committee for the Eastern Central Atlantic. 1987 CECAF/TECH/87/83 FAO (Food and Agriculture Organization for the United Nations). Dakar (Senegal).