Gill-nets

Depending on geographic location and position in the water column, gill-nets are used to target demersal and pelagic sharks, skates and rays. Sharks, skates and rays are also taken as bycatch in some fisheries, as are sea-birds and marine mammals.

Gill-nets are rectangular sheets of netting weighted at the bottom and supported at the surface by a head-line attached to floats, ensuring the net hangs vertically in the water column. Gill-nets can be ‘bottom-set’ - anchored to the seabed to target demersal species, ‘mid-water set’ and ‘surface-set’ - where they target pelagic species. Mesh size varies depending on the target species, as does the height (up to 6m) and length (often several hundred metres). Gill-nets are tightly hung and, with a suitable mesh size, ensure only the head and gill covers of the target species can pass through without being trapped. Loosely set gill-nets are known as tangle-nets: as well as being caught by their gills, fish twisting and turning to escape become entangled. 

For demersal species the main advantage of set gill-nets over towed nets (trawling) is that tightly hung nets - with an appropriate mesh size - can be very size selective, retaining very few juveniles. This fishing method can also be used on very rough grounds which are inaccessible to towed gears. If soak time is kept to a minimum, the condition of the caught fish remains high.

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