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1
PROGRESS REPORT 1st SEMESTER (JANUARY – JULY 2014)
THE ASSESSMENT ON BLUE SWIMMING CRABS (Portunus pelagicus (Linnaeus, 1758)) FISHERIES IN NORTH COAST OF JAVA
Research Center for Fisheries Manageent and Conservation (RCFMC)
Jl. Pasir Putih 1, Ancol Timur, Jakarta-14430
for
Indonesia Blue Swimming Crab Processors Association (APRI) Jl. KIG Raya Selatan Kav C-5, Gresik, Jawa Timur, Indonesia
BACKGROUND • Crab fishery has contributed as one of the source livelihood of small-scale fishers in the
North of Java since the 1970s and still exist seasonally until to date. An intensive
fishing increased since the 1990s, this along with increasing international market
demand (FAO, 2013).
• Blue swimming Crabs (Portunus pelagicus Linnaeus, 1758) is economic important
marine living resources in Indonesian, it ranked under tuna and shrimps. Kailola et al.
(1993) and Ng (1998) stated that this species widely distributed in Indo-Pacific waters,
West Indian and East Pacific Oceans. Sumiono (1997) and Sumiono et al. (2011)
informed that Blue swimming Crabs in Indonesia distributed along the coastal area of
east Sumatera, north of Java, South of Sulawesi, South and East Kalimantan. Among
them, Jakarta and Cirebon Bays, Brebes, Rembang and Madura strait were the main
fishing areas in the north coast of Java.
• Antara News (1989) informed that several species of swimming Crabs in Indonesia,
Portunus pelagicus is the highest export value species in form of picking, cooking,
frozen or caning. The estimate export volume in 2012 is around 28,000 tons, which is
commercially valued at around 330 million USD (Fauzi, 2013). FAO (2011) in Chu et
al., (2012) mentioned that Indonesian annual production fluctuated during period of
1970 to 2008.
• The annual production in 2008 estimated at around 34,000 tons and it contributed 20%
of world production after China. Worldwide policy on sustaining fish for food
(including blue swimming crabs) should consider safety, security and sustainability
2
issues of its resources. Wall Mart, Costco Wholesale, Sam’s Club Whole Foods
Market and others (Crawford, 2013) adopted those mainstreams of world market
system. By 2020, it is expected that world buyers on fish product will only accept
products that have been eco-labeling certified issued by the Marine Stewardship
Council (MSC). There are wide spread informations available on the benefit of applied
best practices sustainable fisheries and its management plan. This ecolabelling
certification voluntarily proposed regarding issues on Fisheries Improvement Project.
• The annual world statistics on blue swimming crab production and within the last 5
years Indonesian (IDN) contribution were around 20%. (Figure 1)
0
20
40
60
80
100
120
140
160
180
200
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
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1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
ESTIMAT
ED LAN
DING
(x 100
0 TO
NS)
WORLD
IDN
Figure 1 The annual world and national landing of blue swimming crabs 1970 – 2012
Source : http://www.fao.org/fishery/species/2629/en 16 November 2014
• Since 2014, RCFMC and APRI carried out a Blue swimming crab fisheries assessment
in the north coast of Java. Observation was carried out through collecting the
dependent and independent fisheries data.
OBJECTIVES
The objective of research project is to provide the present status of blue swimming
crabs fisheries in the Java Sea as a base line information on designing Harvest Control
Rules to support its Fisheries Management Plan.
3
METHODS
Site locations Six site locations were selected as a major data base to collect the data. There are
distribute along the coast of north of Java and South of Kalimantan (Figure 2). Each
location has a different characteristics on fishing gear and its tactic and strategy on BSC
exploitation.
Figure 2. Site locations
Data collecting There are two types of data were proposed to collect during this research project.
First, dependent data on fisheries through regular weekly sampling in representative sites,
miniplant and collectors in the several landing bases i.e Jakarta, Cirebon, Demak,
Rembang, Sumenep (North coast of Jawa) and Sampit (South coast of Kalimantan) and it
consisted of length frequency, catch by type of gear, and effort characteristics. Secondly,
independent data through onboard sampling in a small-scale commercial fishing vessels
measuring size and catch compotition by gear by depth distribution, ecological related
species and possibly the occurrence of ETP species. Observation on oceanographic
parameters i.e. salinity, temperature and bottom substrate profiles and larval abundance.
Data Analysis
A simple model for tropical fish stock assessment will be applied on data analysis.
Several approach to describe stock status and its perspectives including production and
analytical model were used based on size, catch and effort data.
Java Sea
4
Biological aspects Length – weight relationships
Length weight relationship was analyszed through carapace length and weight of
specimens. Regression analysis followed the formula of King (1995):
which :
W = weight (gram) a = (slope) L = carapace length (mm), b = constant
Average size at first maturity (Lm)
Size at first maturity, were estimated through a formula of King (1995)
Remarks:
PLm : proportion of size of specimen mature to immature, a and b : parameters.
Average length at first capture (Lc)
Length at first capture (Lc) by type of gear (collapsible trap, gillnet, trawl) were
calculated through selectivity approach on logictics function (Stewart & Ferrel, 2002). The
formula were as follows:
Remarks: r(l) = probalility retention l = carapace width a & b = constant
Biomass estimation from on board commercial fishing vessel
Stock density were calculated by using swept area method for mini bottom trawl,
(Saeger et al., 1976), with a formula of:
5
Remarks:
D = stock density (kg/ km2) C/t = catch per hour (kg/jam) a = area swept by gear
e = escapement factor = 0,5 (Saeger et al., 1980 dalam Sparre & Venema, 1999)
v = vessel speed (knot) h = head rope length (m)
E = head rope opening = 0.5 (Pauly,1980 dalam Sparre & Venema, 1999)
1,852 = conversion mile to km 1.000 = conversion from meter to km Biomass estimation will be calculated by using a classic equation as follows :
B = D x A
Remarks:
B = biomassa (kg) D = stock density (kg/km2) A = area covered (km2) A general fishing power index will be determined based on catch by type of gear used and its characteristics to fish BSC. Spawning potential ration (SPR)
SPR can be calculated for different levels of Lc and F by dividing spawning stock
biomass under exploitation ( ) by pristine spawning stock biomass ( )
SSBF = existing spawning stock biomass SSBF=0 = pre fishing spawning stock biomass
Biomass calculated at each time-age class and spawning stock biomass is simply
the sum of all biomass above the age at maturity. Spawning stock biomass is calculated as:
6
Wt = the average weight by age at spawn Nt = estimate number of fish by age at spawn Population parameters as an input to this model consisted of:
- Natural Mortalitas (M) - Growth parameters (K, L∞, to) - Regression coefficient (a, b) - Length at first maturity (Lm)
Surplus Production Model
A schaeffer model will be applied to estimate a maximum sustainable yield and its
optimum efforts. An appropriate Harvest Control Rule will be applied to initiate
management measures.
WORKPLAN AND ACHIEVEMENTS
The general scheme on research project
The steps and process of the activities on data collecting, validation and the way to
analyze data were shown in Figure 3. It consisted of several steps from source of data, type
of data measured and observed, preliminary analysis due to on going regular sampling
program and limited on board observation in two main locations. Advance analysis and
draft final report will be carried out in January 2015. Focus group discussion will be
proosed to held in the end of February 2015.
Initiative Performance Indicators of research project
The performance indicators of on going research project were mapped in Figure 4.
Scope of work including data collecting system, data collecting system, type of data,
location, platform and time line were identified and listed. The predicted achievement
level as major research performance indicators showed that there are still items with less of
50% (red). The major component of low indicators is due to data still in hard copies and
some of them still on going process including some amandmend on additional two
locations proposed during the last midterm evaluation.
7
Fishery dependent:• landings• enumerator• sampling
Fishery independent (at sea research):• Charterd
Fishing Boats
• Biological data• Catch• Effort
• Catch composition
• Biological data• Catch composition
• By-‐catch• Catch-‐rate• Larva• Habitats
•Population parameters(L∞,K,to, Z,M,F,E)• Lm• Lc•Indices of stock abundance& recruitment•Est.Biomass & SSB•MSY•Genetic population•Mapping life cycle
Harvest control rule
Stock assesment
FISHERY MANAGEMENT AREA Harvest Strategy
Figure 3. General frame work of BSC research project
Field survey
Draft Report
Dissemination 2nd phase
2014 National Provincial District Crb Dmk Rbg Sum Sam Pas JaB Crb DmkJanuary x x x xFebruary x x x xMarch x x x x xApril x x x x xMay x x x xJune x x x xJuly x x x x x x xAugust x x x x xSept x x x x xOctober x x x x x x mid November x x x x xDecember x x x x x x x x x
January Final February FGD
expected output
Estimated MSY, fopt,
CPUE Fishing Power Index
annual fluctuation
seasonal variabil ity
data validatio
n
data processing
on going done
Achievement (%)
80 10 10 100 0 0 60 60 60
Remarks : Cr = Cirebon Pas = PasuruanL/W = length weight relation ship Dm = Demak JaB = Jakarta BayLm = estimated size at first mature Rb = RembangLc = estimated size at first capture Sum = SumenepCPUE = Catch per unit of effort Sam = SampitMSY = Maximum sustainable Yieldf opt = optimum effort
proposal 2015 -‐2016
60
on schedule
Bio -‐reproduction (Sex ratio, Maturity, L/W, Lm and Lc,
growth parameters, mortality, Exploitation
rates, SPR, PSA
on going
esti Bo , S & T profi le,
Substrate, Larvae, Gear Selectivity
historical annual data 2000 -‐ 2012 catch and estimated effort
Statistic on capture fisheries
quarterly within last 5 years data
monthly within last 5 years data on catch and effort by gears
Enumerators on-‐board
Figure 4. Workplan and its on going achievement
8
PRELIMINARY RESULTS
Landing site observation Since January 2014, local trained enumerators established to measure the biological
aspects such as carapace length, weight, sex and maturity stages. Validating processes
were done in March and July 2014. Fisheries data consisted of catch per trip by gear,
fishing ground were also collected from local fishers through interviewing.
• Three type of fishing gear were used during survey, they are mini bottom trawl,
collapsible trap and bottom gillnet.
Fisheries data • Data consisted of gear description, catch rate and its composition, fishing areas.
Information on environmental condition on substrate, depth, salinity, temperature,
dissolved oxygen and crabs larvae also observed.
• Field identification blue swimming crabs species referred to Ng (1998) and Sumpton et
al. (1994). Fischer & Whitehead (1974); Gloerfelt-Tarp & Kailola (1985); Nakabo
(2000); Carpenter & Volker (1998) were used for fish specimens.
Fishing Gears Bottom gillnet
Length of net (bottom gill net) with maximum 7.000-8.000 meters. It made by
monofilament with mesh size of 3.5” (Figure 3). Fishing operation during dark period and
deployed at midnite for 4 to 5 hours depends on the catch.
Collapsible trap
Fishing vessels with length of 6 – 10 m, breadth 1,5–2,8 m and depth of 0,75–1,5
m. Inboard engine of 16 - 25 PK. Two fish hold covered by fibre with 90 x 60 x 70 cm
sebanyak 2 buah). Number of crew 5 persons. Traps were made by combination of wire
and polyethylene D6. The dimension of 18 cm height, 25 cm width and 40 cm length.
Mouth opening 6-8 cm (Figure 4). Number of traps by trip during sampling was 750 unit.
Dredge net
Dredge net is the active fishing gear. Length of mouth is 2 meter with height of 1,5
meter. Webbing made by PE-multifilamen with mesh size of 0.75-inch dengan ukuran
9
mata in codend is 0.75-inch (Figure 5). Towing at around 1 – 2 hours with speed 0f 1 – 2
knots
Demersal Danish seine
Jaring arad as of one type of demersal Danish seine is used to target shrimps
resource operated with fishing craft of < 5GT. Otter board with size of 40 cm x 80 cm and
thikness 2 cm. Length of wing part at around is 11,2 meter with mesh size at around 24-45
mm, cod end of 1.7 m
Research findings
Biological aspects
• The carapace width frequency distribution in two main locations of Demak and
Rembang (Central Java) showed that the higher average was found in the collapsible
traps. The catch from demersal Danish seine was the lowest average. Gill net mostly
between Danish seine and collapsible trap.
Figure 5. Carapace width distribution by type of gear and locations (januari – August
2014)
10
• The range of carapace width measurement from enumerators were preliminary
indicate that the largest mean by sex occurred in the specimens from Sampit of
south Kalimantan. The smallest mean came from Cirebon west Java (Table 1). This
probably strongly related to relatively healthy habitat and environmental condition
in the area compared to north coast of Java.
Table 1. Minimum, Maximum and mean of carapace width based on enumeration by site
location.
Location Carapace width (mm)
Male Female min max. mean min max mean Cirebon 85,7 146,8 110,0±14,7 72,2 143,3 110,7±18,3 Demak 68,7 168,4 115,3±18,8 59,2 161,9 116,8±18,6 Rembang 70,4 159,2 117,1±15,5 79,0 165,6 117,8±15,8 Sumenep 85,4 147,1 111,8±14,9 77,7 143,8 112,0±18,1 Sampit 87,0 165,0 135,0±14,7 90,0 183,0 130,0±13,8
• The mean carapace width bysex by three types of fishing gear were also observed
and it showed that the largest mean found in specimens caught by collapsible traps.
The smallest size occurred in specimens caught by mini bottom trawl or demersal
Danish seine (Table 2).
Table 2. Mean carapace width by sex, location and type of gear
Gears Mean of carapace width (mm)
Demak Rembang Male Female Male Female
Mini bottom trawl 102,1+15,6 103,9+15,8 Gillnet 102,6+14,7 107,1+13,2 116,9+16,0 110,7+15,6
Collapsible trap 122,1+17,1 124,3+16,8 117,7+15,0 118,8+15,6
• Estimation on length at first maturity (Lm) and length of fisrt capture (Lc) were
also calculated based on specimens measured by site locations. The preliminary
assessment indicated that the highest Lm and Lc occurred in Sampit south
Kalimantan. The smallest values occurred in specimens measured in Cirebon
(Table 3).
11
Table 3. Estimated Lm and Lc by locations
Lokasi Lm (mm) Lc (mm) Cirebon 98.12 116.19 Demak 112.47 115.55 Rembang 101.51 116.58 Sumenep 100.06 111.68 Sampit 126.78 129.50
Rata2 107.79 117.90 Std. Dev. 11.99 6.77
Length weight relationship
• Length weight relationships between male and female were different. B coefficient
of male is always higher than male (Figure 6).
y = 8E-‐06x3.4489R² = 0.8372
n=295
0
50
100
150
200
250
0 20 40 60 80 100 120 140 160
W (gr)
CW (mm)
y = 2E-‐05x3.2597R² = 0.8878
n=123
0
50
100
150
200
250
300
0 50 100 150 200
W (gr)
CW (mm)
y = 9E-‐06x3.4512R² = 0.9544
0200400600
0 50 100 150 200
W(gram)
CW (mm)
Demak
y = 2E-‐05x3.2602R² = 0.9219
-‐150
50
250
450
0 50 100 150 200
W(gram)
CW (mm)
Demak
W= 1E-‐05L3,385R² = 0,941
0
200
400
0 50 100 150 200
W (gram)
CW (mm)
Rembang
W= 3E-‐05L3,191R² = 0,927
0
200
400
0 50 100 150 200
W(gram)
CW (mm)
Rembang
y = 1E-‐05x3,404R² = 0,910
0200400600
0 50 100 150 200
W(gram)
CW (mm)
Sampit
y = 6E-‐05x3,036R² = 0,878
0200400600
0 50 100 150 200
W(gram)
CW (mm)
Sampit
Cirebon Cirebon Cirebon Cirebon
Figure 6 . Carapace width and weight relationships between male and female based on data
from Cirebon, Demak, Rembang dan Sampit
12
• Length at first maturity
Preliminary analysis on estimated length at first maturity were found at around
100.8 cm CW. It seems all the catch were above this value (Figure 7).
13
Figure 7. Estimated length at first mature and length at first capture by locations
Spawning Potential Ratio (SPR)
• SPR is an one of recent reference point could applied for fisheries management and
its measures. Literature study explain that across a broad range of species, a
threshold of 40% SPR is generally accepted as a proxy for Maximum Sustainable
Yield (MSY) and 50% SPR is generally accepted as a proxy for Maximum
Economic Yield (MEY) of a certain fisheries. Situation of stocks are generally
thought to risk recruitment of its stocks is declining when the level of SPR < 20%.
The preliminary exploration on limited data that has been collected showed that the
stocks is relatively not in risk condition (Figure 8).
Figure 8. The estimated Spawning Potential Ratio of BSC
Onboard data collection • Observation on research data through onboard sampling using several types of small
scale fishing gear has been carry out during this first semester. Coastal water of
14
Cirebon and Demak north coast of central Java (Figure 1) were selected as the area to
study.
• First survey was carried out in Cirebon on July 2014. A number of 14 trawl sampling
stations (Figure 9), including 9 stations were collected. The geographical location of
fishing activities by type of gear were showed in Figure 10. Distribution of fishing
station and catch rates by Danish seine (Figure 11), dredge net (Figure 12)
108.4°E 108.45°E 108.5°E 108.55°E 108.6°E 108.65°E 108.7°E 108.75°E 108.8°E 108.85°E 108.9°E-6.9°S
-6.85°S
-6.8°S
-6.75°S
-6.7°S
-6.65°S
-6.6°S
-6.55°S
-6.5°S
-6.45°S
-6.4°S
12
3 4 5
6
789
10
11
12
13
14
Gebang
CIREBON
Figure 9. Oceanographic Sampling stations on July 2014.
Figure 10. The sampling fishing area by gill net, dredge and demersal Danish seine.
15
Figure 11. Distribution of fishing station of demersal danish seine and its catch rates in
Cirebon, Juli 2014
Figure 12. Fishing stations by dredge net and its catch rates in Cirebon, Juli 2014
Ecological Related Species
• Issues on the ecological related species is one of the information to measure the
ecosystem impact of fisheries activities. The List of ecological related species of
BSC fisheries were slightly different by type of gear. This occurred due to the
technical efficiency and performance of the gear. Specific analysis will be held on
108.4°E 108.45°E 108.5°E 108.55°E 108.6°E 108.65°E 108.7°E 108.75°E 108.8°E 108.85°E 108.9°E-6.9°S
-6.85°S
-6.8°S
-6.75°S
-6.7°S
-6.65°S
-6.6°S
-6.55°S
-6.5°S
-6.45°S
-6.4°S
Gebang
CIREBON
Tangkapan Ikan Demersal (kg)
0.475 to 1.34 1.34 to 1.992 1.992 to 4.13 4.13 to 5.511
Remarks: 100,472 -‐ 149,07 kg/km2
90,85 kg/km2
42,045 kg/km2
Gebang
Java Sea
J ava Sea
16
after survey completed. The list of species and its composition by four type of
fishing gear used by fishers were showed in Figure 13, 14 and 15.
Gill net
Figure 13. Catch composition of ecological related species caught by gill net
Dredge net
Figure 14. Catch composition of ecological related species caught by dredge net in Cirebon
2014
17
Demersal Danish seine
Figure 15. Catch composition of ecological related species caught by demersal dansih
seine net in Cirebon 2014
Estimated density
• The catch rates of BSC during fishing with demersal Danish seine were showed in
Table 4. The estimate density ranged between 42 to 159 kg/km2, the value is
relatively high compare the actual fishers estimates. Some detail data exploration
will be held after the last on-board observation were completed.
Table 4. Catch rate and stock density of BSC caught by Danish seine in Cirebon waters,
July 2014.
No Latitude Longitude Setting
time (hr)
Total catch (kg)
Catch rate (kg/hr)
Stock density
(kg/km2) 1 6046,305' 108044,305' 0.75 100.47 133.96 100.47 2 6046,724' 108045,090' 0.83 42.04 50.45 42.04 3 6045,649' 108044,303' 0.83 nd nd nd 4 6045,657' 108044,111' 0.92 104.23 113.71 104.23 5 6046,584' 108043,342' 0.47 90.85 194.68 90.85 6 6047,167' 108043,558' 0.47 149.07 319.44 149.07
Total 4.27 486.67 812.24 486.67 Average 0.71 81.11 135.37 81.11
Nd= unsuccessful haul
18
Oceanographic Parameters
• Oceanographic stations were collected simultaneously before or after trawl
sampling. The parameter consisted of temperature, salinity, dissolved oxygen and
measured by using water quality checker tipe WQC 22A. Substrate and
macrobenthic were collected by using grab bottom sampler of 20x20 cm or 0.04
m2. A bongo net were used to collect crab larvae. Substrate were observed by using
Millar triangle to obtain sand, dust and dan clay (Brower et al., 1990).
• The physical water body and substrate characteristics were listed in Table 5 and 6.
Futher analysis will be carried out after completed the second surveys at different
monsoon.
Table 5 . Data on oceanographic parameter survey in Cirebon and adjacent waters, July 2014
Depth Transparency(m) (m) Surface Bottom Surface Bottom Surface Bottom Surface Bottom
1 -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐2 9 6 28.3 28.2 32 32 5.9 6 6.3 5.3 Muddy3 7 6 28.5 28.1 32 32 7 6.1 6.9 6.8 Muddy4 7 2 29 28.7 31 32.5 6.6 6.4 6.4 6.5 Muddy5 8 2 29.5 29 30 31 6 5.9 6.3 6.4 Muddy6 6 0 28.2 27.9 31 31 7 6.7 6.8 7.6 Muddy7 2 0.5 28 28 29 29 7 7 7.3 7.3 Muddy8 -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐9 -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐10 9 2.5 29.2 28.6 30 30 7.3 7.4 6.6 7.3 Muddy11 -‐ -‐12 8 3 28.3 28.2 31 32 5.5 6.6 8.6 8.7 Muddy13 -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐ -‐
Sta. No.pHWater temp (oC) DO (ppm)Salinity (‰) Substrate type
Remarks: - no data vailable
Table 6. Subtrate type in Cirebon and adjacent waters, July 2014
No. No. Sta. Substrate texture (%) Substrat type Sand Dust Mud
1 1 3.52 0.50 95.98 Muddy 2 2 4.02 1.51 94.47 Muddy 3 3 5.53 1.01 93.47 Muddy 4 4 4.02 1.51 94.47 Muddy 5 5 3.02 1.01 95.98 Muddy 6 6 3.02 1.01 95.98 Muddy 7 7 3.02 10.05 86.93 Muddy 8 10 4.02 0.50 95.48 Muddy 9 11 2.51 1.01 96.48 Muddy
19
Larval Abundance
• Preliminary analysis on occurrence of predicted BSC larvae were listed in
Table 7. It showed that the maegalopa were mostly found in Station No. 10
and 11 which geographically located to near shore around mangroves.
Table 7. The estimate of BSC larval abundance in Cirebon and adjacent waters, July 2014
Stadia Est. abundance (ind./m3) St. 1 St. 2 St. 3 St. 4 St. 5 St. 6 St. 7 St. 10 St. 11
Zoea 1 1873 2548 573 2675 2956 15 19 96 3121 Zoea 2 420 204 541 1376 892 15 42 96 1847 Zoea 3 204 127 319 255 25 15 31 32 1147 Zoea 4 51 0 64 51 0 10 11 32 382
Megalopa 0 0 0 0 0 0 0 32 32 REFERENCES Brower, J.E., J.H. Zar & C.N.V. Ende. 1990. Field and laboratory method for general
ecology. Third edition. Wm.C.Brown Publisher. Dubuque. Iowa: 40-120 Carpenter,K.E & H.N.Volker (Eds). 1998. The Living Marine Resources of the Western
Central Pacific. Vol. 2. Cephalopods, Crustaceans, Holothurians and Sharks. FAO, Rome, Italy
Gloerfelt-Tarp, T. & P. Kailola. 1985. Trawled fish of the southern Indonesia and northern Australia. ADAB –GTZ-DGF Indonesia : xvi + 406 p.
Fischler, KJ & C.H Walburg. 1962. Blue crab movement in coastal South Carolina, 1958-59. Trans. Am.Fish. Soc. 91:275-278.
Fischer,W & P.J.P. Whitehead, 1974. FAO Species Identification Sheets for Fishery Purposes. Eastern Indian Ocean and Western Central Pacific. FAO-UN Rome.
Nakabo, T., 2000. Fishes of Japan with pictorial keys to the species. Second Edition. Tokai University Press. 2-28-4, Tomigaya, Shibuya-ku, Tokyo.
Ng PKL. 1998. Crabs. In Carpenter, K.E. & V.H.Niem (Eds.). FAO Species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. FAO-UN. Vol. 2. Rome :1045 - 1155.
Ravi R & M.K Manisseri. 2012. Survival Rate and Development Period of the Larvae of Portunus pelagicus (Decapoda, Brachyura, Portunidae) in Relation to Temperature and Salinity. FAJ(49):1-8.
Smith H. 1982. Blue Swimmer Crabs in South Australia – their Status, Potential and Biology. Safic. 6(5):6-9.
Sumpton,W.D., M.A. Potter & G.S.Smith. 1994. Reproduction and Growth of the Commercial Sand Crab, Portunus pelagicus (Linn.) in Moreton Bay, Queensland. Asian Fish.Sci. (7): 103-113.
20
APPENDIX 1. Larvae of BSC (stadia zoea 1, zoea 2, zoea 3, zoea 4 and megalopa) caught in Cirebon and adjacent waters, July 2014