1) Environmental data was collected from Lake Taal in the Philippines, including bathymetry, water quality parameters, currents, sediments, and chlorophyll-a. 2) Preliminary modeling of the lake's flushing rate and carrying capacity was conducted to determine suitability for aquaculture. 3) Production data from tilapia and milkfish cages was analyzed, including stocking densities, growth rates, feeding rates, and food conversion ratios.

1. Environmental monitoring and modelling of aquaculture in risk areas of the Philippines
Preliminary information from Taal, Batangas, Philippines
By: Guttorm N. Christensen1, Rune Palerud1, Patrick White1, Tarzan Legoviz1, Regie Regpala2. 1 Akvaplan-niva, 2 BFAR NIFTDC
Data collected
Bathymetry (depth recordings) of the area
Tidal range and current speed, direction and dispersion
Physical parameters - Temperature, turbidity, salinity, oxygen, profile
through the water column
Water quality – chlorophyll, phosphorous, nitrite, ammonia
Sediment analysis (biological and chemical)
Weather data wind direction, speed, temperature
Taal survey area
Lake Taal CM01 (5,5 m depth)
water transport (l/(s*m^2))
Lake Taal CM03 (7,5 m depth)
water transport (l/(s*m^2))
0
6
15
45
4
300
330
315
30
330
315
0
345
15
6
255
225
210
45
60
285
2
75
270
0
90
255
CTDO01
L a k e T a a l 1 0 . 0 4 .0 5 .
75
0
90
4
8
105
0
2
6
S a li n i ty ( P S U )
8
0
0 .4
0 .8
1 .2
T e m p e r a tu r e ( ° C )
1 .6
2
26
27
30
31
135
150
CM 01
195
180
165
195
165
180
135
150
0
345
#
#
#
#
#
255
180
0 .4
0 .8
1 .2
T e m p e r a tu r e ( ° C )
27
28
1 .6
29
10
2
30
#
60
#
#
17
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4
6
8
10
O x y g e n ( m g /l)
0
4
6
S a lin it y ( P S U )
8
0
0 .4
0 .8
1 .2
T e m p e ra tu re (°C )
1 .6
2
26
135
150
2
27
30
31
28
29
10
0
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6
60
45
80
60
2
270
#
40
30
4
300
285
D e p th ( m )
CM 04
Lake Taal CM04 (10,5 m depth)
water transport (l/(s*m^2))
345
#
40
100
CTDO 06
L a k e T a a l 1 0 .0 4 .0 5 .
#
#
330
315
0
75
90
255
CTDO 07
L a k e T a a l 0 3 .2 9 .0 6 .
105
0
240
C h l o r o p h y l l - F ( µ g /l )
2
4
165
180
0
0
6
15
285
#
#
8
8
0 .8
1 .2
T e m p e r a tu r e (° C )
27
28
1 .6
29
10
2
30
40
60
80
7
45
60
2
270
4
6
S a li n i t y ( P S U )
20
#
30
4
300
0 .4
26
Lake Taal CM06 (10,5 m depth)
water transport (l/(s*m^2))
345
2
0
D e p th (m )
195
6
O x y g e n ( m g /l )
0
135
150
# CM 06
330
315
#
120
225
210
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C h lo r o p h y ll - F ( µ g /l)
2
105
120
#
#
#
# #
CM 02
90
165
0
26
CTDO06
0
195
8
8
0
20
60
75
225
210
6
4
6
S a lin ity ( P S U )
10
45
240
2
20
30
2
#
29
CTDO01
270
#
0
30
285
#
28
4
O x y g e n ( m g /l )
24
10
# CM 05
4
300
20
2
80
135
150
15
6
16
4
0
Lake Taal CM02 (10,5 m depth)
water transport (l/(s*m^2))
330
315
12
0
O x y g e n ( m g /l )
120
225
210
C h l o r o p h y l l - F ( µ g /l )
C h lo r o p h y ll - F ( µ g /l)
120
225
210
# CM 03
105
240
180
165
CTD O 17
L a k e T a a l 0 3 .3 0 .0 6 .
60
2
240
120
195
45
255
105
240
30
270
90
30
4
300
0
15
285
75
270
Lake Taal CM05 (8,5 m depth)
water transport (l/(s*m^2))
2
0
6
4
300
60
285
345
D e p th (m )
345
D e p th ( m )
330
315
0
75
#
90
255
#
105
240
225
210
120
195
180
165
Bathimetry of taal.dbf
#
1.1 - 10 m
#
10 - 30 m
#
30 - 60 m
#
60 - 90 m
#
90 - 166.7 m
135
150
Salinity, temperature and oxygen
stations and measurements
Current meter stations and
measurements
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Bathymetry of Taal Lake
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Chlorophyll-taal.dbf
1 - 4 ug/L
#
4 - 8 ug/L
#
8 - 12 ug/L
# 12 - 16 ug/L
# 16.1 - 22 ug/L
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Sediment-oct05.dbf
# 1 Very good
# 2 Good
# 3 Bad
# 4 Very bad
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#
#
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Secchi all.dbf
#
0.2 - 0.7 m
#
0.7 - 2 m
#
2-4m
#
4 - 20 m
#
#
Chlorophyll-A measurements
Sediment condition
Secchi disc measurements
Modelling of carrying capacity for aquaculture production
Calculation of carrying capacity of the Taal Lake
Flushing rate.
The average yearly rainfall is 1882.9 mm while the average
evaporation is 116.75 mm, so the net water layer entering
the Lake is 1766.15 mm over the watershed and the lake.
In addition to the lake, the watershed is 4.2 108 m2.
Volume of the part of the estuary under consideration is
#
V = 2.43 * 109 m3.
The volume is derived from the surface area of the lake,
which is 2.43 * 108 m2 and the depth of the upper 10 m.
Hence the yearly inflow is 1.2 109 m3 and the flushing rate
is D = (inflow=outflow)/V = 0.494 1/year.
#
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The lake needs 2 years to renew one volume of water to
the depth of 10 m.
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Production data
Tilapia Fish Cage
Date
Milkfish Fish Cage
Range
30 March 2006
Date
30 March 2006
Type
Fish Cage - square
Type
Fish Cage - round
Net Volume (m3)
700 to 1000
837.5
Net Volume (m3)
1000 to 1508
1177
Species
Tilapia
Tilapia
Species
Bangus
Bangus
Stocking Density (fry/m3)
62 to 214
153.8
Stocking Density (fry/m3)
12 to 34.5
20.3
Present Density (kg/m3)
0.62 to 7.5
4.14
Present Density (kg/m3)
3.34 to 8.6
4.10
Present Size (g)
#
Range
Average
50 to 500
221.5
Present Size (g)
2 to 250
225
2,467
Present biomass
311.75
Final market size (g)
250g to 500
336
16.9
Survival (%)
50 to 96
84
Present Biomass (kg)
Average
4,826 kg
Final market size (g)
Survival (%)
4.3 to 50
Culture period (months)
4 to 7
5.75
Culture period (months)
5.5 to 6
5.67
Final density
2.5 to 10
7.45
Final density
5 to 9.9
5.72
Feed given (kg/day)
5 to 100
60.5
Feed given (kg/day)
75 to 300
144
Feeding rate
1.45 to 4.45%/day
2.45%/day
Feeding rate
1.45 to 4.45%/day
2.98%/day
FCR
Location of fish cages
225g to 500
2.14 to 2.5:1
2.22:1
FCR
1.67 to 2.5:1
2.14:1
#
Interviews with tilapia cage
farmers
Interviews with milkfish cage
farmers