Surrounding nets with a purse line (purse seines)
According
to fisheries statistical record for 1982, there were 840 registered purse seiners. Most
of them were in the 10-100 gross ton category, and used luring devices. Some
had modern equipment on board, such as wireless set radio communication, echo-sounder,
sonar, and radar. In 1985, some boats even had satellite navigation. Many
auxiliary fishing gears were used on board; capstan winch (mechanical of hydraulic),
davit pulley, boom crane, electric generator, fish luring lamps and power block. There
were no freezers on board; instead, wet or dry ice was used. A characteristic
of this method of fishing is a rather large manpower requirement, which may,
in time, become a disadvantage.
Chinese
or two-boat purse seine (Uan tang-ke)
This
kind of purse seine has been known to Thai fishermen for
nearly 60 years. It has not changed much during that
time, except that cotton netting has been replaced by nylon,
and fishermen on longer sail around looking for fish but
rather use fish luring lamps. This old-fashioned gear
still remains in use on the Andaman Sea coast (Phuket, Trung,
Satun), because of its special advantages, such as low operating
cost, effectiveness in difficult fishing grounds and good
commercial value of catch.
Several
vessels are required for an operation. The mother
boat is a 16-20 m long wooden vessel with a 100-250 h.p.
main engine. To rowing-boats (8 x 2x 0.8 m) are used
as net boats, and another rowing-participate in an operation.
The
net is rectangular, 350 x 60 m, made of black-colour 25 mm
nylon 210 d/9-12. Polyethylene, 25 mm, 380 d/15, is used
for selvedge. Two purse lines, polyethylene cross-rope,
28-32 mm, are fixed to the middle of the net. The
net is spread out by two rowing-boats, in areas around islands
or banks, where the bottom is rocky or sandy hills. The
catch includes scad, barracude, cavalla, trevally Spanish
makerel, mackerel and bonito.
Anchovy
purse seine (Uan lom chub pla katak)
This
gear is similar to anchovy surrounding net, except that a
purse ring is attached to the sinker line, and the bottom
of the net can be closed with the purse line. A 10-20
m wooden vessel with a 20-150 h.p. engine, and 10-30 fishermen
are needed for fishing operation.
The
net is rectangular, 250-400 meters long and 15-50 meters deep. Float line is
shorter than sinker line (E=0.83/E=0.93). Main net is blue polyethylene
minnow net 2 x 2 mm and/or green nylon rachel net 6.5 – 8.3 mm 110 d – 210
d/5. Polyethylene 380 d/12-15, 25 mm, is used for selvedge at sinker
line. Iron purse rings are attached on sinker line at intervals of 1.5-2
meters. A 26-32 mm polyethylene cross-rope is used for purse line. Buoyancy
force is about twice the sinking power.
A
fishing operation is usually conducted in the early morning
and evening time. Fish schools are saught by eye, but
sometimes fish luring lights are operate at night. Anchovy
purse seine can be found on the east coast of the Gulf of
Thailand (Rayong, Chantaburi, and Trat), the southern east
coast (Surat Thani) and the southern part of the west coast
of Thailand, in Phuket, Krabi and Satun.
Thai
purse seine (Uan daum)
Before
1960, most purse seines in Thailand were of this type. The
difference between this and any other purse seine lies not
so much in construction, but in the manner of operation. Nowadays,
large vessels have sonar equipment for fish detection, but
in the past and even today in the case of small vessels,
a fish school has to be spotted by eye, in the twilight. Sometimes,
however, Thai purse seines are operated with the fish luring
lights and fish shelters, which causes some confusion in
fishery statistical records (see Table 1.4).
The
fishing vessel is 14-14 m long, with a 20-200 h.p. engine,
and 10-30 fishermen on board.
The
net is rectangular, 400-600 m long, 70-110 m deep, cod-end
is in the middle of the net. The main net is 25-43.8
mm nylon 210 d/6-12, float line is shorter than sinker line
(E = 0.6-0.7/E=9.65-0.75). The buoyancy force is 1.3-2
times higher than the sinking power. The colour of
the net is black or green.
Fishing
operation is conducted from a single boat. The net
is hauled by hand on both sides of the boat, whereas the
purse line is pulled by a capstan winch which is driven by
the main engine. The catch consists largely of Indo-Pacific
mackerel and scad. The fishing grounds are in the eastern
and western Gulf of Thailand, inner Gulf, and the southern
part of the Andaman Sea; the main ports are Samut Sakhon,
Chonburi, Langsuan (Chumporn province) and Kantant (Trang
Province).
Luring
purse seine (Uan Sung and Uan Tageang)
Most
purse seines in Thailand are used in conjunction with one
of the two luring methods; fish shelter and fish luring lights. A
fish shelter (Sung) is constructed of bamboo poles,
wire and coconut leaves, and fastened to a concrete block. This
luring method is used in day-time fishing. Fish luring
lamps (Tageang), which can be either electric or
gass lamps, are used in night-time fishing.
A
luring purse seine is 400-800 m long, 80-100 m deep. The
main net has 20-25 mm mesh-size, the material is black nylon
210 d/4-12 and polyethylene 380 d/12-15 at the cod-end. The
float line is shorter than the sinker line (E=0.7-0.8/E=0.75-0.85). The
ratio between the depth and the length of net is 1/5 – 1/7. The
fishing boat is 18-24 m long (20-80 gross tons), with a 100-400
h.p. engine. Thirty to forty fishermen are needed
for an operation.
The
main catch are sardine, round-scad, selar-scad, and Indian
mackerel. Fishing grounds of fish shelter purse seine
are in the central Gulf of Thailand (40-60 meters depth),
while fish luring lights are used both in the Gulf of Thailand
and the Andaman sea (20-40 meters depth). Main fishing
port for fish shelter purse seine are Pattani and Samut Prakan,
whereas Chumporn, Prachuap Khirikhan, Phuket, Trang and Satun
are the main fishing port for fish luring lamp purse seine.
Fish
schools are detected by sonar. Fishing is done at nigh,
usually in the central Gulf of Thailand, and sometimes in
the South China Sea. The catch comprises long-tail
tuna, eastern little tuna, jack, trevallies, cavalla and
others. The fishing ports are in Rayong, Songkhla and
Pattani.
Tuna
purse seine (Super seiner)
During
the past fifteen years (1982-1997) the most advance Thai
fishing gear and methods is Tuna purse seine on the Super
seiner. In 1987, the Department of Fisheries of Thailand
has emploied one large fisheries research vessel, name R.V.Chulaporn.
Her basic construction is trawler, then she was designed
to be multipurpose of fishing with composed of stern trawler,
longliner, gill netter and purse seiner. In 1994, The Southeast
Asian Fisheries Development Center, Training Department has
emploied a multipurpose fishery research and training vessel,
name M.V.SEAFDEC. Her basic construction is Tuna Purse Seiner
(Super Seiner) then longliner, gill netter and pot fishing
were designed to work on for some cruise and some period.
Then in 1995, Department of Fisheries, Thailand emploied
a new Tuna Fisheries Research Vessel name R.V.Mahidol, she
is a 1,270 gross tonnage super seiner, a typical type tuna
purse seiner. Then, in 1998 Thai Off shore fisheries Association
has emploied a used tuna purse seiner about 1,800 gross tonnage,
she was also a typical tuna purse seiner, All most of them
are operated in the Indian Ocean and Andaman Sea.
Their
fishing nets vary from 1,000 to 2,000 meters in length and
250 to 300 meters in depth and mesh size are 90 millimeters
at bunt part and 210 millimeters at the body and wing, and
all of them operate by fish aggregating devices, FADs or
paayao. The target catch are skipjack, yellow fin and big
eye tuna while their by-catch are rainbow runner, horse mackerel,
leather jacket and dolphin fish.
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