* Trollers - catch fish by towing astern one of more trolling lines. A trolling line is a fishing line with natural or artificial baited hooks trailed by a vessel near the surface or at a certain depth. Several lines can be towed at the same time using outriggers to keep the lines apart. The lines can be hauled in manually or by small winches. A length of rubber is often included in each line as a shock absorber. The trolling line is towed at a speed depending on the target species, from 2.3 knots up to at least 7 knots. Trollers range from small open boats to large refrigerated vessels 30 meters long. In many tropical artisanal fisheries, trolling is done with sailing canoes with outriggers for stability. With properly designed vessels, trolling is an economical and efficient way of catching tuna, mackerel and other pelagic fish swimming close to the surface. Purpose built trollers are usually equipped with two or four trolling booms raised and lowered by topping lifts, held in position by adjustable stays. Electrically powered or hydraulic reels can be used to haul in the lines.
http://www.hickerphoto.com/fishing-troller-15073-pictures.htm
Japanese squid jigger in Cook Strait
* Jiggers - there are two types of jiggers: specialised squid jiggers which work mostly in the southern hemisphere and smaller vessels using jigging techniques in the northern hemisphere mainly for catching cod.
* Squid jiggers - have single or double drum jigger winches lined along the rails around the vessel. Strong lamps, up to 5000 W each, are used to attract the squid. These are arranged 50–60 centimetres apart, either as one row in the centre of the vessel, or two rows on each side. As the squid are caught they are transferred by chutes to the processing plant of the vessel. The jigging motion can be produced mechanically by the shape of the drum or electronically by adjustment to the winch motor. Squid jiggers are often used during the day as midwater trawlers and during the night as jiggers.
* Cod jiggers - use single jigger machines and do not use lights to attract the fish. The fish are attracted by the jigging motion and artificial bait.
Other vessels
* Dredgers - use a dredge for collecting molluscs from the seafloor. There are three types of dredges: (a) The dredge can be dragged along the seabed, scooping the shellfish from the ground. These dredges are towed in a manner similar to beam trawlers, and large dredgers can work three or more dredges on each side. (b) Heavy mechanical dredging units are operated by special gallows from the bow of the vessel. (c) The dredger employs a hydraulic dredge which uses a powerful water pump to operates water jets which flush the molluscs from the bottom. Dredgers don't have a typical deck arrangement, the bridge and accommodation can be aft or forward. Derricks and winches may be installed for lowering and lifting the dredge. Echosounders are used for determining depths.
http://www.hickerphoto.com/fishing-troller-15073-pictures.htm
Japanese squid jigger in Cook Strait
* Jiggers - there are two types of jiggers: specialised squid jiggers which work mostly in the southern hemisphere and smaller vessels using jigging techniques in the northern hemisphere mainly for catching cod.
* Squid jiggers - have single or double drum jigger winches lined along the rails around the vessel. Strong lamps, up to 5000 W each, are used to attract the squid. These are arranged 50–60 centimetres apart, either as one row in the centre of the vessel, or two rows on each side. As the squid are caught they are transferred by chutes to the processing plant of the vessel. The jigging motion can be produced mechanically by the shape of the drum or electronically by adjustment to the winch motor. Squid jiggers are often used during the day as midwater trawlers and during the night as jiggers.
* Cod jiggers - use single jigger machines and do not use lights to attract the fish. The fish are attracted by the jigging motion and artificial bait.
Other vessels
* Dredgers - use a dredge for collecting molluscs from the seafloor. There are three types of dredges: (a) The dredge can be dragged along the seabed, scooping the shellfish from the ground. These dredges are towed in a manner similar to beam trawlers, and large dredgers can work three or more dredges on each side. (b) Heavy mechanical dredging units are operated by special gallows from the bow of the vessel. (c) The dredger employs a hydraulic dredge which uses a powerful water pump to operates water jets which flush the molluscs from the bottom. Dredgers don't have a typical deck arrangement, the bridge and accommodation can be aft or forward. Derricks and winches may be installed for lowering and lifting the dredge. Echosounders are used for determining depths.
