fisheries oceanography

1. FISHING
GEAR

2. Sojib ahmed
ASH171801
0M
Dept of

3. NO Topic Name
01 Prelude
02 Fishing gear
03 Method of fishing
04 Fishing by gear
05 Fishing screens
06
07
Fishing traps
08 Hooks and lines
09 Net fishing
10 Types of net
11 Trawl net
12 Classification of trawl net
13 Advantage and disadvantage of trawl net

4. Prelude:
Fish is the major source of animal protein in the diet of the people of
Bangladesh contributing 60% of the total animal protein supply. The per capita
demand for consumption of fish is 19.30 kg per annum in 2013-2014 (DoF, 2015).
Marine fisheries contribute 16.78% of total fish production of Bangladesh (DoF, 2015).
Marine fisheries are divided into industrial and artisanal fisheries. Industrial
fisheries based on trawl fishery (shrimp & fish), which contributes only 12.93% and
artisanal fisheries contribute 87.07% of the total marine landings (DoF, 2015). In the
year of 2013-2014, the total marine fish production was 5, 95,385 metric tons of
which 5, 18,500 metric tons comes from artisanal fishing (DoF, 2015). The future of
fisheries is very much dependent on fishing gear selection, mode of operation,
fishermen’s number, intensity of fishing and level of exploitation.

5. Fishing Gears:
Fishing gear refers to any form of equipment, implement, tool
or mechanical device used to catch, collect or harvest fish.
Active gears:
• Fishers usually guide the gear into the path of the fish.
• e.g., trawls, dredges, seine nets
Passive gears:
• The fish has to come to the gear.
• Hooks Detailed knowledge of fish behaviour is needed to
successfully construct and locate passive fishing gears.
• e.g., gillnets, traps, some types of hooks
.

6. Method of Fishing:
On the basis of use of gear, fishing are of basic
two types -:
1) Fishing by gear (Gear Fishing)
2) Fishing without gear (Hand Fishing)
Fishing by Gear
1) Fish Screens
2) Fish Traps
3) Line Fishing
4) Net Fishing
5) Fish Attraction Devices (FADs)
6) Electrical Fishing

8. Fish Screens
The screen are set to surrounded a shallow tidal
area at the time of high floods. When the flood
water recedes the fish are left behind in the
muddy pool and are collected.
Screen are also set to mark off shallow areas of
river.
By this method is employed to catch Carps,
Catfish, Murrells etc.

10. Fish Traps
*Various type of traps are used to catch of fish
which are allowed and prevent from escaping of
fish.
* It is also called as Cover-pot or Basket trap.
* A large number of fisherman are together in
muddy water by this method.
*Live fishes like : Channa, H. fossilis, Clarias
batrachus are easily catch by trapping

12. Hooks & Line Fishing
* Long-lining is one of the most fuel-efficient catching
methods.
* This method is used to capture all type of fishes and also
able to perform in Rivers, Sea, Ponds, Lacks, Pools etc.
* The lines may be set vertically in the water column, or
horizontally along the bottom.
* The size of fish and the species caught is determined by
hook size and the type of bait used.

13. Types of Lining Fish
Catching
*Lining is a modern fishing method. Modern fishing lines are usually
made from artificial substances.
* Lining method are basically divided into three types -:
1) Drop lining - A Dropline usually shorter than longlines and
have fewer hooks. Droplines have a weight at the bottom and a float
at the top.
2) Handlining - It is a single fishing line method by a single
person. Handlining can be done from boats or from the shore.
3) Longlining - is a commercial technique that uses a long
heavy fishing line with a series of hundreds or even thousands of
baited hooks hanging from the main line by means of branch lines
called "snoods". Longlines are usually operated from specialized boats
called longlines.

15. Net Fishing
* Netting is the principal method of commercial
fishing.
* The most common form of fishing for recreational
fishers is “net” called netting. It is mostly used by
commercial fisherman to catch fish in large scales.
* While there are many types of nets, all rely on the
fish
getting snared or caught in the net's mesh. Nets are
typically long, narrow and flat, weighted at the
bottom
edge and supported at the top edge by floats.

16. Types of
Net
1) Dip net or Lift net
2) Cast net
3) Purse net
4) Drag net
5) Shore sienes or Rampani net
6) Trawl net

17. Dip Net or Lift Net
*Dip net are formed in a several shapes like :
square
or rectangular, triangular, etc.
* Dip net lowered into the water in the hope that
fish would swim over them and lifted out of water.
8 Lift nets can be categorized into four names -:
1) Hela Jal
2) Kharra Jal
3) Bhesal Jal
4) Khoursal Jal

18. Types of Lift Net or Dip Net

19. Cast Net
*It is also called “Ghagaria Jal”.
* It is a circular net which is looks like the
umbrella shape.
* It is extensively used in ponds and rivers and
all along the sea coast.
* It is can’t be used in weedy place or rocky
bottom place.

20. Cast Net

21. Purse net
*It is a purse shaped net and operated from a boat.
* The net is then "pursed", drawing the bottom closed
and entrapping the fish.
* Purse nets cannot be used by recreational fishers.
* Two kinds of purse net are used to catching fishes-
1) Kharki Jal
2) Shangla Jal

22. KHARKI JAL
(Purse Net)
SHANGLA JAL
(Purse Net)

23. Drag net
*Drag nets are held apart with triangular bamboo
frame & pushed manually to fish traditional water of
river ,beels & flood plains locally called moijal.
GILL NET
* It is also known “Fixed Net”.
* Gill nets are walls of netting which may be set at or below
the surface, on the water bed, or at any depth in between.
* Gill netting is probably the oldest form of net fishing,
having been in use for thousands of years.
* Netting is almost invisible, fish swim right into it; and their
gills get caught

24. DRIFT NET
• Large floating nets
• Unbreakable and invisible to most sea
species
• likely to entangle large pelagic species :
dolphins, whales, sharks, turtles, and rays.
• Driftnets have earned the nickname “walls of
death”.
•

25. A Type of Drift Net

26. Shore sienes or Rampani
net:
* Rampani nets are a wall of net divided into three
layers.
* An inner fine-meshed net is sandwiched between
two outer, larger meshed nets.
* Rampani Net are also two types -:
1) Fixed Rampani Bag Net
2) Moveable Rampani Net

27. Moveable Rampani Net

28. Trawl Net
It is a bag net of synthetic twine which is drawn along the sea-bed to harvest fish
on or near the bottom.
*It is under nets
 Active Fishing Gear
 Cone Shaped Body
 Most Versatile Fishing Technique
 Trawl net can be operated at the surface, mid-water, bottom.
 Sea water > Fresh water bodies.
 Not used in artisanal fisheries.

29. Trawl
net

30. Classification of Trawl
1. Based on mouth opening device
a) Beam trawl
b) Bull trawl
c) Otter trawl
2. Based on the depth of operation
a) Bottom trawl
b) Mid water trawl/Pelagic trawl
3. Based on the construction pattern
a) Two seam trawl
b) Four seam trawl
c) Six seam trawl

31. BEAM TRAWLING
Beam trawling is one of the most destructive form of bottom trawling, in
which a large net attached to a heavy metal beam is dragged across the sea bed
behind a boat, digging into and ploughing up the ground.
Bull Trawl
The boat which shoots the net open by t in bull or pair trawling by using two vessels.
Otter Trawls
Trawl towed on the sea-bed, held open by a pair of otter boards. It is much larger net than a beam
trawl.
Bottom Trawl
Trawl towed along the sea-bed. These dragged along the bottom.

32. • Beam trawl
– Trawl towed on the sea bed in which the net is held open by a
wood /steel
beam.
• Bull trawl
– The boat which shoots or hauls the net in bull or pair trawling i.e.
by using
two vessels.
• Otter trawl
– Trawl towed on the seabed, held open by a pair of otter boards. It
is much
larger net than a beam trawl.
• Bottom trawl
– Trawl towed along the seabed. Those dragged along the bottom.
• Mid water trawl
– Trawls can be towed be in mid water to catch the pelagic species
.

33. Advantages of Trawl Net
Disadvantages of Trawl Net
1. Effective
2. Large scale fishing operation
3. Can catch bottom, demersal and pelagic species
4. Commercially profitable
1. Disturbs and destroy the seabed including sea-
grasses, coral reefs, rock-gardens where fishes hide
from predators, spawning grounds.
2. By catches ( turtles, sea-birds, marine mammals,
unwanted fish caught & thrown away).
3. Overfishing gear is nonselective and discards a lot
of sea fish.

34. Dredging
*Dredging is used for harvesting bivalve molluscs such as
oysters, clams and scallops from the seabed.
*A dredge is a metal framed basket with a bottom of connected iron
rings or wire netting called a chain belly.
*The lower edge of the frame has awaking bar, with or without
teeth, depending upon the species targeted.
*The catch is lifted off the seabed or out of the sea by the raking (or
teeth) bar and passes back into the basket or bag

35. Fish Attraction
Devices
*Various species of fish often associate with
other living creatures.
* e.g. tuna associate with dolphins and whale
sharks.
*Some associate with objects floating or
suspended in the sea.
* This natural phenomenon has been
exploited to attract fish to floating or
suspended structures.

36. Fish Attraction
Devices
* Such structures can provide known locations for
congregating fish, around which vessels can
operate a wide range of fishing techniques
including purse seines, pole and line or trolling
*FADs may be used to concentrate fish in
sufficiently high numbers which are then
surrounded with a purse seine net.

37. ELECTRICAL FISHING
* Electric fishing is a new technique has been
developed by using of low voltage electric current.
* The fish always swim towards the positive pole of
electric current and electrode with increasing
potential.
* The advantage of this method is that even the large
size of fishes which escape being caught by taking
shelter under stones, rocks etc., can be easily caught

38. Dive-caught
Free diving (using
mask and snorkel)
or scuba diving is a
traditional method
of collecting lobster,
abalone, seaweed,
sponges and reef
dwelling fish
(groupers and
snappers).

39. Fishing without
gears
In some rivers and streams of the hills
or near
dams & reservoirs. Water flows into
narrow
channels & fish are caught by hands.