Gill net

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Contents:-
Introduction of gill net
Necessary equipment
Description of gill net
Caught species
Mode of capture
Types of gill net
Impacts of gill net

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Introduction of gill net
Gill net are widely used both in marine and inland water
throughout the world.
It is a highly selective fishing gear.
It is passive fishing gear.
Gill net may be made up from single net, double net and tripple
netting walls.
It may be operated in surface water, midwater and bottom water.
Gill net can be set with Anchor to the bottom.
Gill net can be free or connected to the vessel.
These nets can be used either alone or usually in large number
called fleets of nets.
Hanging coefficient of gill net-0.56
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Gill net
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Gill net
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Necessary equipment
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Small floats
Sinkers
Anchors
Buoys

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Floats
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Floats Usually made of plastic
attached to the head rope.
Floats help in keeping the gear
at the required depth.
Floats should be buoyant.
Floats should not absorb water.

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Sinkers
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Sinkers are evenly distributed along
the foot rope of gill net.
Sinkers are used to keep the net in
the desire position
Sinkers are made up from stones,
rocks,bones,and lead.

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Anchor
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 Anchor used for setting the net
into bottom.
 Anchor is normally made up
from metal

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Buoys
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 Buoy denote the current position
of gill net.
 Buoy attached to the fishing gear
by the buoy line.

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Description of gill net
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 Gill net is highly selective fishing gear.
 In the gill net fishes are caught by gilling.
 Gill net are generally used by both commercial and artisanal fishers in both
marine water and freshwater bodies.
 It has simple design and operation with low investment.
 It is also used by small scale fisherman because of its selective nature.
 Gill netting is one of the most suitable fish catching method from conservation
point of view.

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 It is a long wall of webbing kept suspended in the water and the meshed size
of the net is calculated in such a way that the fish can pass its head but not
the body.
 A twine otherwise called mounting twine attaches the webbing to the head
rope and foot rope.
 Several pieces of webbing are laced together prior to operation by means of
brace line(the line used for lacing the adjoining shots in a fleet of gill net).
 A few rows of meshes in the periphery of the net are called selvedge made of
thicker twine and large vessels to protect the main netting by taking up the
excess pressure.

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Gilling
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Gill net fishing in the sea
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Caught species
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Gill net is suitable for sparsely
distributed and scattered fish
population.
Fishes caught by gill net:-
Salmon
Pomfrets
Seer fish
Lobsters
Mullets
Shark
Tuna
Shad
Seabass
Mullet

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Mode of capture
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 Fish may be caught by gill nets in
four ways:-
1. Gilling
2. Snagging
3. Wedging
4. Entangling

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 Gilling – held by mesh around their gill.
 Snagging -held by meshed around their head.
 Wedging– held by the mesh around the body.
 Entangling – held by teeth, spines, maxillaries, or other protrusions
without the body penetrating the mesh.

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Types of gill net
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 The gill net are classified based on the:-
1. Methods of construction
2. Methods of operation
3. Depth of operation
4. Target species

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1.Simple wall gill net
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 These are single walled gill nets
without line.
 These nets kept vertical in the
water with sinkers and floats

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2.Vertical line gill net
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 Vertical line gill nets are set
vertically in water bodies.
 These are Prefer in areas of
lower fish population

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3.Framed gill net
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 Line are passed both vertically
and horizontally show that squire
compartment of about 1-2 meter
are formed in the webbing.
 These net is useful for catching
larger fishes especially from the
reservoirs.

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4.Trammel net
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 These consist of three layers of
webbing.
 The outer layer are made of
larger meshes and thicker twine
and called armour.
 The middle layer is called “lint”
and is made of smaller meshes
of thinner twines
 These nets are more useful for
different size fishes.
 In trammel net fishes swim easily
through the outer meshes but get
entangle in pocket through the
smaller meshes.

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5.Combined gill net
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 In combine gill net webbing of
different mesh size are joint
together.
 These can be single walled or
two walled .
 In two wall net one wall is of
larger mesh and other is of
smaller meshes .
 It is useful in water were different
size groups of same species
swim together.

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Based on method of operation
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 Set gill net
 Drift gill net
 Encircling gill net

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Set gill net
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 Set gill net are set in water either
on surface, sub-surface or
bottom fixed in a substrate with
anchor to prevent the movement
of the gear.

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Drift gill net
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 Drift gill net drift in water with
current and wind with no anchor .
 Floats and sinkers attached to
the head rope and foot rope of
the net .
 Buoys attached to the head rope
of the net for location of the net

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Encircling gill net
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 Encircling gill net surrounds an
area and the fishes are frightend
and then caught by gilling

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Based on depth of operatrion
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 Surface gill net
 Midwater gill net
 Bottom gill net

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Surface gill net
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 Surface gill net are operated on
the surface water with floats ,
sinkers,buoys and anchors.
 Surface gill net are commonly
used for catching pelagic fishes.

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Midwater water gill net
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 Midwater gill net are used in
midwater with floats, sinkers,
buoys and anchors.
 Midwater gill net are used for
catching mid water fishes.

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Bottom gill net
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 Bottom gill net are operated in
bottom water with floats, sinkers,
buoys and anchors.
 These are mainly used for
catching bottom fishes.

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Based on the target species
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 Tuna gill net
 Shrimp gill net
 Sardine gill net

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Tuna gill net
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 Tuna gill net are generally used
for catching tuna fishes .

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Shrimp gill net
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 Shrimp gill net are used for
catching shrimp in water bodies.
 Shrimp gill net is used in bottom
water because shrimps are
bottom dweller.

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Sardine gill net
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 Sardine gill net is used for
catching sardine fishes.
 Sardine gill net is surface gill net.

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Impacts of gill net
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 By-catch
 Ghost fishing

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By-catch
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 By-catch is a accidental catch
which entangle in the net during
operation of gill net.
 Accidental catches-
 marine mammals
 sea turtles
 Seabirds
 sharks

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By-catch Reduction
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 Many factors are used for reducing accidental catches
Like:-
 Breakaway panels
 Changing net slack
 Changing mesh size
 Set depth.

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Ghost fishing
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Ghost fishing refers to lost or
abandoned fishing gear.
Which is also called derelict fishing
gear
Which continuous to capture fish
and other marine animals.
After some times fishes are die in
the gear.
After many days fishes becomes
like ghost .
So it is called ghost fishing.

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Conclusion
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Gill net is a highly selective fishing gear.
Gill net are widely used in both marine and freshwater ecosystem in the world.
Ghost fishing is a major problem in the gill net.

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Gill net

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