Journal of Fisheries & Livestock Production
Open Access

Gillnetting is a fishing system that uses gillnets perpendicular panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are occasionally called “corks” and the line with corks is generally appertained to as a “cork line”. “The line along the bottom of the panels is generally ladened. Traditionally this line has been ladened with lead and may be appertained to as” super eminent line. “A gillnet is typically set in a straight line. Gillnets can be characterized by mesh size, as well as color and type of filament from which they’re made [1].

Mesh sizes are designed to allow fish to get only their head through the network but not their body. The fish’s gills also get caught in the mesh as the fish tries to back out of the net. As the fish struggles to free itself, it becomes more and more entangled. A variety of regulations and factors determine the mesh size, length, and height of marketable gillnets, including area scrabbled and target species. There are two main types of gillnets

Set gillnets are attached to poles fixed in the substrate or an anchor system to help movement of the net.

Drift gillnets are kept round at the proper depth using a system of weights and buoys attached to the head rope, footrope, or float line.

Gillnetting has been a major source of mortality for all sea turtle species: Turtles encountering a gillnet can quickly come entangled around their head or flippers as they try to escape. Entangled turtles will drown if held under the water but have a advanced chance of survival if they can reach the surface to breathe. The nylon can strain around the turtle’s soft body corridor and beget deep cuts potentially leading to infections, limited movement, or complete loss of the branch. Limited use of accessories can vitiate a turtle’s natural feeding, breathing, and swimming geste [2].

Gillnets are long blockish panels of netting with diamond- shaped mesh that are held vertically in the water column and anchored to the ocean bottom at either end. Fish swim into the net and are entangled by the gills, fins and backbones. The nets are kept perpendicular by the docks along the top and weights along the bottom. Only demersal gillnets (touching the ocean’s bottom) are permitted in Commonwealth fisheries, and are used by one Commonwealth fishery to catch academy and sticky sharks. Gillnets are typically used in shelf waters lower than 100m deep.

Gillnets have a minimum impact on the substrate as they’re stationary when set. Gillnets have the eventuality to interact with marine mammals, although when set duly, larger raptorial harpies and marine mammals will bounce off the tight mesh. Relate to AFMA’s Australian Sea Lion Management Strategy and Dolphin Strategy.

Gillnet mesh size is regulated by AFMA so that substantially medium size sticky wolf are caught. The shrimp harpies are suitable to swim through the mesh and larger harpies bounce off the net. This leaves both lower harpies who have not had the chance to reproduce and large parentage harpies in the water.

All gill nets are fairly size picky as the size range of fish caught can be regulated by the mesh size used. Small fish will swim unchecked through the mesh whereas larger bones will be caught. Frequently the veritably large fish will’ bounce ‘off the net without getting caught in the net. Gill nets are also species picky due to the area that they’re shot in, the commander will use his experience to place his gear where he expects there to be a cornucopia of the target species thereby reducing the chances of by-catch [3-5].

There can be problems with cetacean by catch in some areas but in utmost fisheries the commanders are formerly apprehensive of this and have espoused the use of aural fritters to keep the cetaceans down from the gear. In numerous fisheries moment the use of pingers is obligatory.

Seabed contact with gill nets is limited to veritably light contact from the footrope and minimum contact from the small anchors at each end. As the gear isn’t hauled over the seabed there should be veritably little bruise. There have been reports of problems with ‘ghost fishing ‘in the history, this is where the nets are lost and continue fumbling for some time after they’re lost. There have been attempts to alleviate this by encouraging fishers to report lost gear so that it can be recaptured at an after date and to bring ashore any poorly damaged gear for disposal. It has also been plant that in numerous areas, lost nets will veritably snappily get entangled with weed and become visible to the fish and ultimately sinks to the seabed. However lost nets still remains a problem for fish and marine mammals.

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1. Uhlmann SS, Broadhurst MK (2015) Mitigating unaccounted fishing mortality from gillnets and traps. Fish Fish 16(2): 183-229.

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2. Olin M, Kurkilahti M, Peitola P, Ruuhijarvi J (2004) The effects of fish accumulation on the catchability of multimesh gillnet. Fish Res 68: 135-147.

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3. Holst R, Madsen N, Moth-Poulsen T, Fonseca P, Campos A (1998) Manual for gillnet selectivity. European Commission: 43.

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4. Hamley JM (1975) Review of gillnet selectivity. Journal of the Fisheries Board of Canada 32(11): 1943-1969.

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5. Reeves RR, McClellan K, Werner TB (2013) Marine mammal bycatch in gillnet and other entangling net fisheries, 1990 to 2011. Endanger Species Res 20(1): 71-97.

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