2 LITERATURE REVIEW
2.1 The Description of the Gillnet
Gillnet is a wall of netting which may be set at or below the sea surface, on the sea bed, or at any depth between. Fish are caught by gilled, or by entangled as
they attempt to pass through the net, which may be classified as a gillnet, tangle net or trammel net depending on the manner in which the net is constructed and
the way the netting is hung Sainsbury, 1996. True gillnets are simply used to catch fish with body size of almost uniform
since the mesh size matched to the fish’s girth: the mesh size used depends on the species and size range being targeted. The net is constructed so that the meshes
are virtually square in shape and large enough that the fish can get its head through, but not its body, so that it becomes caught by at the gill cover on
attempting to back out. These nets are used for a wide range of species including small pelagic, cods and haddock, bass, and salmon Sainsbury, 1996.
Trammel nets are constructed of three panels of netting attached to the same framing ropes. A middle sheet of webbing of small, loosely hung mesh is rigged
between outside walls of large mesh. A fish striking from either side passes through the large outer mesh web and hits the small mesh netting which is carried
through the openings of the other large mesh webbing to form a sack or pocket in which fish is entrapped Sainsbury, 1996.
Various methods of setting gillnets are: 1 bottom set gillnet. Net may be set out end to end for up to a mile, but more usually are set in a pattern across or
around an area where fish are known to travel. Lead line maintains net in position on the bottom while the float line provides sufficient buoyancy to stretch the
twine. 2 Off-bottom gillnets. Net position is maintained by appropriate adjustment of buoyancy in floats and float line compared to the weight of the lead
line. 3 Surface drift gillnet. Surface floats are used; the lead line stretches the twine and the depth below the surfaces is adjusted by the length of the lines to the
floats Sainsbury, 1996.
Kategori