Types
| Type | Image | Target fish | Description | Environmental impact |
|---|---|---|---|---|
| Bottom trawl | Demersal fish such as groundfish, cod, squid, halibut and rockfish | A trawl is a large net, conical in shape, designed to be towed along the sea bottom. The trawl is pulled through the water by one or more boats, called trawlers or draggers. The activity of pulling the trawl through the water is called trawling or dragging. | Bottom trawling results in a lot of bycatch and can damage the sea floor. A single pass along the seafloor can remove 5 to 25% of the seabed life. A 2005 report of the UN Millennium Project, commissioned by UN Secretary-General Kofi Annan, recommended the elimination of bottom trawling on the high seas by 2006 to protect seamounts and other ecologically sensitive habitats. In mid October 2006, US President Bush joined other world leaders calling for a moratorium on deep-sea trawling. | |
| Cast net | Schooling and other small fish | Cast, or throw nets are small round nets with weights on the edges which is thrown by the fisher. Sizes vary up to about four metres in diameter. The net is thrown by hand in such a manner that it spreads out on the water and sinks. Fish are caught as the net is hauled back in. | High discrimination possible. Non targeted fish can be released unharmed. | |
| Coracle net fishing | Coracle fishing is performed by two men, each seated in a coracle, plying his paddle with one hand and holding a shared net with the other. When a fish is caught, each hauls up his end of the net until the two coracles are brought to touch and the fish is secured. | |||
| Dragnet | This is a general term which can be applied to any net which is dragged or hauled across a river or along the bottom of a lake or sea. An example is the seine net shown in the image. The fishing depth of this net can be adjusted by adding weights to the bottom. | |||
| Drift net | The drift net is a net that is not anchored, but is drifting with the current. It is usually a gill or tangle net, and is commonly used in the coastal waters of many countries. Its use on the high seas is prohibited, but still occurs. | |||
| Drive-in net | A drive-in net is another fixed net, used by small-scale fishermen in some fisheries in Japan and South Asia, particularly in the Philippines. It is used to catch schooling forage fish such as fusiliers and other reef fish. It is a dustpan-shaped net, resembling a trawl net with long wings. The front part of the net is laid along the seabed. The fishermen either wait until a school swims into the net, or they drive fish into it by creating some sort of commotion. Then the net is closed by lifting the front end so the fish cannot escape. | |||
| Fyke net | Fyke nets are bag-shaped nets which are held open by hoops. These can be linked together in long chains, and are used to catch eels in rivers. If fyke nets are equipped with wings and leaders, they can also be used in sheltered places in lakes where there is plenty of plant life. Hundreds of these nets can be connected into systems where it is not practical to build large traps. | |||
| Gillnet | Sardines, salmon, cod | The gillnet catches fish which try to pass through it by snagging on the gill covers. Thus trapped, the fish can neither advance through the net nor retreat. Uses a system of nets with floats and weights. The nets are anchored to the sea floor and allowed to float at the surface | Animals cannot see the net, so they swim into it and are tangled. High risk of bycatch. | |
| Ghost net | Ghost nets are nets that have been lost at sea. They may continue to be a menace to marine life for many years. | |||
| Hand net | Hand nets are held open by a hoop and are possibly on the end of a long stiff handle. They have been known since antiquity and may be used for sweeping up fish near the water surface like muskellunge and northern pike. When such a net is used by an angler to help land a fish it is known as a landing net. In England, hand netting is the only legal way of catching eels and has been practised for thousands of years on the River Parrett and River Severn. | |||
| Landing net | ||||
| Lave net | A special form of large hand net is the lave net, now used in very few locations on the River Severn in England and Wales. The lave net is set in the water and the fisherman waits till he feels a fish hit against the mesh and the net is then lifted. Fish as large as sturgeon are caught in lave nets. | |||
| Lift net | A lift net has an opening which faces upwards. The net is first submerged to a desired depth, and then lifted or hauled from the water. It can be lifted either manually or mechanically, and can be operated on a boat or from a shore. | |||
| Midwater trawl | Pelagic fish such as anchovies, shrimp, tuna and mackerel | In midwater trawling a cone-shaped net is towed behind a single boat and spread by trawl doors (image), or it can be towed behind two boats (pair trawling) which act as the spreading device. | Midwater trawling is relatively benign compared to the damage bottom trawling can inflict on the sea bottom. | |
| Plankton net | Research vessels collect plankton from the ocean using fine mesh plankton nets. The vessels either tow the nets through the sea or pump sea water onboard and then pass it through the net. | |||
| Purse seine | Schooling fish | The purse seine, widely used by commercial fishermen, is an evolution of the surround net, which in turn is an evolution of the seine net. A large net is used to surround fish, typically an entire fish school, on all sides. The bottom of the net is then closed by pulling a line arranged like a drawstring used to close the mouth of a purse. This completely traps the fish. | Higher chance of bycatch | |
| Seine net | A seine is a large fishing net that may be arranged in a number of different ways. In purse seine fishing the net hangs vertically in the water by attaching weights along the bottom edge and floats along the top. A simple and commonly used fishing technique is beach seining, where the seine net is operated from the shore. Danish seine is a method which has some similarities with trawling. In the UK seine netting for Salmon and Sea-trout in coastal waters is only permitted in a very few locations and where it is permitted one end of the seine must remain fixed and the other end is then waded out and returns to the fixed point. This variant is called Wade netting and is strictly controlled by law. | |||
| Shore Operated Stationary Lift Nets | Pelagic species | These are held horizontally by a large fixed structure and periodically lowered into the water. Huge mechanical contrivances hold out horizontal nets with diameters of twenty metres or more. The nets are dipped into the water and raised again, but otherwise cannot be moved. The nets may hold bait or be fitted with lights to attract more fish. The most famous examples are found at Kochi, India, where they are known as Chinese fishing nets (Cheena vala). Despite this name, this technique is used all the world. They are also widely used on the Atlantic coast of France, where they are operated from small huts built over the water on stilts, known as carrelets. | ||
| Shrimp net | ||||
| Stake net | A stake net is a form of net for catching fish in shallow inter-tidal zones. It consists of a sheet of network stretched on stakes fixed into the ground, generally in rivers or where the sea ebbs and flows, for entangling and catching the fish. | |||
| Surrounding net | A surrounding net surrounds fish on all sides. It is an evolution of the seine, and is typically used by commercial fishers. | |||
| Tangle net | Tangle nets, also known as tooth nets, are similar to gillnets except they have a smaller mesh size designed to catch fish by the teeth or upper jaw bone instead of by the gills. | |||
| Trammel | A trammel is a fishing net with three layers of netting that is used to entangle fish or crustacea. A slack central layer with a small mesh is sandwiched between two taut outer layers with a much larger mesh. The net is kept vertical by the floats on the headrope and weights on the bottomrope. |
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