Gillnets can be characterized by mesh size, as well as colour and type of filament from which they are made. Fish may be caught by gillnets in three ways:
Wedged – held by the mesh around the body.
Gilled – held by mesh slipping behind the opercula.
Tangled – held by teeth, spines, maxillaries, or other protrusions without the body penetrating the mesh. Traditionally this line has been weighted with lead and may be referred to as "lead line." A gillnet is normally set in a straight line. The floats are sometimes called "corks" and the line with corks is generally referred to as a "cork line." The line along the bottom of the panels is generally weighted. Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water.
Most often fish are gilled. Mesh size, twine strength, as well as net length and depth are all closely regulated to reduce bycatch of non-target species. Gillnets have a high degree of size selectivity. When it struggles to free itself, the twine slips behind the gill cover and prevents escape.[1]
Gillnets are so effective that their use is closely monitored and regulated by fisheries management and enforcement agencies. Most salmon fisheries in particular have an extremely low incidence of catching non-target species.[2]. A fish swims into a net and passes only part way through the mesh.
Surrounding net
A surrounding net is a fishing net which surrounds fish and other aquatic animals on the sides and underneath. There is typically a purse line at the bottom, which is closed when the net is hauled in. It is typically used by commercial fishers, and pulled along the surface of the water.
There are floating buoys on the top of the net and weights on the bottom of the net to make sure that it forms a wall. A surrounding net is deployed by a fishing boat that starts sailing in a circle. This is one of the easiest ways to trap a school of fish. This allows for the net to come all the way around 360 degrees to completely surround the fish. This makes it so that there is no escape for the fish. One negative of surrounding nets is the fact that they might catch an animal that they are not intentionally trying to catch, but this does not happen all that often. As stated above, a seine net is one of the most common types of surrounding nets used in the commercial fishing industry.
Lift net
Lift nets, also called lever nets, are a method of fishing using nets that are submerged to a certain depth and then lifted out of the water vertically. The nets can be flat or shaped like a bag, a rectangle, a pyramid, or a cone. Lift nets can be hand-operated, boat-operated, or shore-operated. They typically use bait or a light-source as a fish-attractor.[1] Lift nets are also sometimes called "dip nets", though that term applies more accurately to hand nets.[2].
This differs when lamps are above the surface either one or several, or if under water lamps are used; with the former. The active gear depends on the attraction power of light when light attraction is used. Lift nets are hauled out by hand or mechanically through bomm(s) and blocks. The operations from the shore, from a canoe or a bigger boat includes the setting of the net at a certain depth opening facing upwards- the attraction of the fish over the above mentioned opening by light or bait, then the lifting and hauling of the net out of the water manually or mechanically.
The Target species are small pelagic species, fish and squid.
Water Area Overview: All over the world.
These net are active a few meters below the surface. The handling (setting and hauling) of large lift nets, normally requires in addition one or several winches.
Drift net :
These nets usually target schools of pelagic fish. Folds of loose netting, much like a window drapery, snag on a fish's tail and fins and wrap the fish up in loose netting as it struggles to escape. The nets are kept vertical in the water by floats attached to a rope along the top of the net and weights attached to another rope along the bottom of the net.[1] Drift nets generally rely on the entanglement properties of loosely affixed netting. Drift netting is a fishing technique where nets, called drift nets, hang vertically in the water column without being anchored to the bottom. However the nets can also function as gill nets if fish are captured when their gills get stuck in the net. The size of the mesh varies depending on the fish being targeted.
Trawl net
The net used for trawling is called a trawl. Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. Trawls are often called towed gear or dragged gear. This principle requires netting bags which are towed through water to catch different species of fishes or sometimes targeted species.
Trawling is also commonly used as a scientific sampling, or survey, method.[1]. The boats that are used for trawling are called trawlers or draggers. Trawlers vary in size from small open boats with as little as 30 hp (22 kW) engines to large factory trawlers with over 10,000 hp (7.5 MW). While trawling involves a net and is typically done for commercial usage, trolling instead involves a reed, rod and a bait or a lure and is typically done for recreational purposes. Trawling can be carried out by one trawler or by two trawlers fishing cooperatively (pair trawling).
Trawling can be contrasted with trolling.
Ghost net
They can entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and other creatures, including the occasional human diver.[2] Acting as designed, the nets restrict movement, causing starvation, laceration and infection, and suffocation in those that need to return to the surface to breathe.[3] It's estimated that around 48,000 tons of ghost nets are generated each year,[4] and these may linger in the oceans for a considerable time before breaking-up. Ghost nets are fishing nets that have been abandoned, lost or otherwise discarded in the ocean.[1] These nets, often nearly invisible in the dim light, can be left tangled on a rocky reef or drifting in the open sea.
Tangle net
Left in the water for no more than two days, and allowing bycatch to be released alive, this net is considered to be less harmful that other nets. When spent, these nets can be bundled, and left on the sea floor to collect smaller species. These bundles are known locally as lumen lumen nets. The tangle net is used in the Philippines by commercial fishermen, as well as by the scientific community. Similar to a gillnet, the tangle net, or tooth net, is a type of nylon fishing net.
Hand net
A hand net with a long handle is often called a dip net. When it is used by an angler to help fetch out ("land") a hooked fish, it is called a landing net.[1]. A hand net, also called a scoop net, is a fishing net or meshed basket held open on a rigid hoop, which may or may not be mounted to the end of a handle.
Bottom trawler
Midwater trawling catches pelagic fish such as anchovies and mackerel, whereas bottom trawling targets both bottom-living fish (groundfish) and semi-pelagic species such as cod, squid, shrimp, and rockfish. Bottom trawling can be contrasted with midwater trawling (also known as pelagic trawling), where a net is towed higher in the water column. The scientific community divides bottom trawling into benthic trawling and demersal trawling. Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". Benthic trawling is towing a net at the very bottom of the ocean and demersal trawling is towing a net just above the benthic zone.
Cast net
This technique is called net casting or net throwing. The net is cast or thrown by hand in such a manner that it spreads out while it's in the air before it sinks into the water. Fish are caught as the net is hauled back in.[1] This simple device is particularly effective for catching small bait or forage fish, and has been in use, with various modifications, for thousands of years.
Plankton net
Plankton nets are considered one of the oldest, simplest and least expensive methods of sampling plankton.[1] The plankton net can be used for both vertical and horizontal sampling.[1] It allows researchers to analyse plankton both quantitatively (cell density, cell colony or biomass) and qualitatively (e.g. Chlorophyll-a as a primary production of phytoplankton) in water samples from the environment. It consists of a towing line and bridles, nylon mesh net, and a cod end. A Plankton net is equipment used for collecting samples of plankton in standing bodies of water.
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