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Grouper and Snapper Fisheries in Thailand, Vietnam, Philippines, Malaysia and Indonesia, MRAGWWF 2007
MARD, Fisheries law, Circular no. 022006TT-BTS Pillay, K.K. N.B. Nair 1971. The annual reproductive cycles of Ucaannulipes,
Portunuspelagicus and Metapenaeusaffinis Decapoda: Crustacea from the South-west coast of India. Marine Biology 112: 152-166.
Potter, I.C. S. de Lestang 2000. Biology of the blue swimmer crab Portunuspelagicus in Leschenault Estuary and Koombana Bay, south-western Australia. Journal of the Royal Society of
Western Australia 83: 443-458.
Williams, M.J. 1982. Natural food and feeding in the commercial sand crab Portunuspelagicus Linnaeus, 1766 Crustacea :Decapoda : Portunidae in Moreton Bay, Queensland. Journal of
Experimental Marine Biology and Ecology 592-3: 165-176.
3 BACKGROUND TO THE FISHERY
3.1 History, location and scale of the fishery
The fishery is based in province of Kien Giang, south of the Mekong Delta, close to the boarder with Cambodia between latitude 8-10º and longitute 103’8-104’4. There are two towns with large fleets.
These are Ha Tien, and Phu Quoc. Other districts with smaller numbers of swimming crab vessels are Kien Luong, Hon Dat districts. The island of Phu Quoc is also used as a landing site. However, there
are also a large number of smaller craft based from the small villages along the coast. The fishery is also demarcated into four areas areas
1
: • No fishing within 2 nautical miles
• vessels 15 hp, fishing from 2 nm or 4 metres to the 8 metre isobath; • vessels 15hp-33 hp, fishing from the 8 metres isobath to around 18 metres.
• Vessels, 33 hp, fishing from 24 nautical miles or approximately at the 18 m isobath
Map 1: Blue swimming crab Fishing area, Kien Giang province
Source: DARD
The larger vessels fish the offshore areas 24 nm off
Phu Quoc, Tho Chu and Chuoi islands
The fishery is reported to have grown. However, the rate of fleet
growth is unclear. The jump in boat numbers
Table 2, between 2007 and 2008, is more a reflection of the
announcement of a fuel subsidy in this period, with more existing
smaller craft registering. The fleet composition by size group
is shown in Table 3.
1
This is different than national operational demarcation zones which are set at different horse power limits See section 7.3
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Table 2: Number and characteristics of boats in Kien Giang province
2005 2006
2007 2008
2009 No’ vessels
1,117 1,118
1,039 3,234
3,823 Total hp
28,137 28,870
28.145 86,760
97,324 Average hp
25.19 25.82
27.09 26.10
25.46
Table 3: Fleet composition by hp size band.
HP group 21 HP
21 - 45 45 - 90
90 - 150 150- 250
250 - 400 Total
No. of
vessels 2.861
446 422
31 61
2 3.823
Source: DARD; Note: the demarcation groups are consistent with national boundary laws. It appears that the crab fishery zones differ from these, but fleet data is only available following the national demarcation
standards.
There are now an estimated 20,000 crab fishers involved. It is not known how many of these are fully active. The first sale market value of US 75 million.
Fishing nets are recorded from 4-12 nautical miles long for the smallest boats, to around 12 or more nautical miles for the larger vessels. Nets are made of monofilament and usually comprise individual
sheets of 100-150 metres. The height of the net is around 1 m, but may reduce in the water to half this depth. The mesh size used is between 70-100 mm Table 4. The nets are set in triangular patterns, at
30º angles, over the length of ground covered.
Table 4: Gear configurations by boat horse power group
Horse power group Net length km
Net height m Mesh size mm
15 4-8
0.7-0.8 70-80
15-33 8-20
0.8-0.9 80-90
33 20+
0.9-1.1 90-100
Source: DARD The high season is from May to September, but fishing periods are different for the larger and smaller
boats. The smaller craft fish between October to March as the crab move closer to shore to spawn. Fishing inside 2 nautical miles is banned. All fishing takes place over mud. Fishing in and around
mangroves and in estuaries is not permitted. There is a closed season for the near-shore from 1
st
April to 30
th
June annual. The smaller boats those less than 33hp will fish day trips commencing at 05.00 hrs to 14.00 hrs, and
fishing tends to take place in periods of stronger tidal drift. The net soak times are between 2 to 3 hours.
The larger boats 33hp fish from 05.00 hrs to 18.00 hrs, but seldom at night because of conflict with trawlers on the same ground. The boats fish 9-10 trips per annum, each trip lasting up to 30 days.
However, this may fall in the low season from 10-20 day trips, depending on the catching opportunities. Crabs are collected from these boats by collector boats.
All crabs are landed whole. There are no other target species. The total blue swimming crab catch from the boats is 11,399 tonnes Table 5. The by-catch accounts for 10 of the total DARD. The
combined levels of other species Shark Nebrius ferrugineus and others
2
, Ray species not identified and sole species not identified, account for 5.2, and slipper lobster species not
identifiedgastropod species not identified, 4.8. The bycatch is either consumed by the crew or
2
Other shark species were not identified during the assessment, but is known to comprise one other than Nebrius ferrugineus.
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sold to the local villages.
Table 5: Catch by crab tangle net boats 2008
Species Tonnes
Crab 11,399
90 Shark
169 1.5
Rays 253
2.2 Sole
169 1.5
Gastropodesslipper lobster 547
4.8 Total
12,538 100.0
Source: By-catch data extracted from fisher interviews. The fishery is an open access fishery. Fishing effort has increased in two ways. The nets used have
more than doubled in size in the last 20 years; and the inshore fleet has increased markedly
3
, stimulated by both economic opportunity, but also by a Government ban on the use of push net and
trawl in inshore waters with the incentive to transfer fishing method to tangle netting. DARD state that there is a decline in CPUE. Fishers interviewed stated that trip catches had remained constant but
they had doubled the length of gear deployed. The average size of crab is reported as constant at around 110 mm YCC purchase records, with the balance in male female crabs being 40:60 for
small boats and 70:30 for large boats
4
. Catch rates are recorded at 15-30kgday for small boats, and 70-80kg for larger boats. Average sizes
for smaller boats are recorded at 10-15 individualskg, and for larger boats, 4-6 individualskg. Spawning females averaged 150 gindividual, but between 100g to 400 g.
Berried females are landed regularly.
4 BIOLOGY
4.1 Life cycle
