REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Use of Ichthyoplankton Survey
in Fisheries Resource
Management
Nygiel Armada
Regional Technical Working Group
(Fisheries)

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Presentation Outline
· Establishment of fish refugia
· Recruitment
· Ichthyoplankton survey
· Some practical applications

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Fisheries Management Intervention
Establishment of "Fish Refugia"
Protecting specific life stage/s of a fish stock
Enhance Recruitment
Sustainable Fisheries

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Russel's axiom
(Russel 1931)
Stock
Natural
Growth
Death
Recruitment
Fishing

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Surplus production
(Schaefer 1954, Fox 1970)
Cost of fishing
Yield
MSY
MEY
Fishing effort

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Yield per recruit analysis
(Beverton and Holt 1957)

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Stock-Recruitment curve
(Ricker 1954, Beverton and Holt 1957)
Replacement line
Recruitment line
Surplus
production
Equilibrium density or
Carrying capacity
Recruits (numbers)
Stock size (numbers)

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Recruitment
Spawning stock size
Fecundity (spawning strength)
Ichthyoplankton density

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Ichthyoplankton survey
Provides information on potential recruits:
What species of fish?
Where they are found?
How many (density)?
Seasonal fluctuations?

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Plankton
stations
12.05
33
11
10
5
32
1
12
9
7
4
2
6
13
11.95
8
3
14
16
15
17
18
19
20
21
25
11.85
26
30
22
27
23
Map of plankton stations
28
24
29
31
in Calamianes, Palawan
in May 2004 (Campos
2004)
11.75
119.90
120.00
120.10
120.20
120.30

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Fish eggs
distribution
Fish Eggs
12.05
11.95
0 to 0.01
0.01 to 25
Density (no./100m3)
11.85
25 to 100
100 to 250
250 to 6596
distribution of fish eggs
in Coron Bay in April
2004 (Campos 2004)
11.75
119.90
120.00
120.10
120.20
120.30

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Fish larvae
12.05
Fish Larvae
distribution
11.95
0 to 0.01
11.85
0.01 to 10
Density (ind./100m3)
10 to 25
25 to 50
distribution of fish
50 to 182
larvae in Coron Bay in
April 2004. (Campos
2004)
11.75
119.90
120.00
120.10
120.20
120.30

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Yolk sac larvae 12.05
Yolk Sac
distribution
11.95
0 to 0.01
11.85
0.01 to 2
2 to 25
25 to 65
Distribution of yolk sac
larvae in Coron Bay in
April 2004 (Campos
2004)
11.75
119.90
120.00
120.10
120.20
120.30

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Fish larvae
Larval Density
Standard
Relative Abundance
composition
Larvae Families
(ind/100m3)
deviation
(%)
Gobiidae
4.99
12.68
29.4
Mullidae
2.58
5.39
15.2
Pomacentridae
1.33
3.98
7.8
Scombridae
1.07
1.78
6.3
Atherinidae
0.98
3.23
5.8
Terapontidae
0.87
2.61
5.1
Blenniidae
0.63
1.54
3.7
Monacanthidae
0.41
1.64
2.4
Cynoglossidae
0.35
2.04
2.1
Sphyraenidae
0.21
0.73
1.2
Labridae
0.20
0.85
1.2
Clupeidae
0.13
0.58
0.8
Callionymidae
0.13
0.41
0.7
Sillaginidae
0.12
0.72
0.7
Apogonidae
0.06
0.37
0.4
Lethrinidae
0.06
0.37
0.4
Engraulidae
0.05
0.27
0.3
Carangidae
0.05
0.27
0.3
Trichiuridae
0.05
0.27
0.3
Gerreidae
0.04
0.24
0.24
Polynemidae
0.04
0.24
0.24
Priacanthidae
0.04
0.20
0.21

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
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Circulation
pattern
General tidal
circulation in Coron
Bay (Villanoy 2006).

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
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Dispersal
simulation
Simulation of
dispersal in Coron
Bay (Villanoy 2006).

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
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Source and Sink
April Dispersal
Source areas and relative amounts of dispersed particles settling in each of the areas marked by the
colored boxes. Colored bars within each box represent the sources of the particles that settled in a
particular box. L= 20 days, R=30 days. (Villanoy, 2006)

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Source and Sink
January Dispersal
Sink areas and relative amounts of particles dispersed from each of the areas marked by the colored
boxes. Colored bars within each box represent where the particles released from a source box ended
up. L=20 days, R=30 days.

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Simulated
12.05
dispersal
11.95
11.85
Simulated dispersal
resulting from tidal
circulation in Coron
Bay (Villanoy 2006). 11.75
119.90
120.00
120.10
120.20
120.30

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Simulated
12.05
dispersal
11.95
Simulated
dispersal with
wind effects
typical of April
(Villanoy 2006).
11.85
Red ellipses indicate areas
where settled particles
originate from several
sources. Grey lines
indicate possible but weak
dispersal, apparent only
after 30 days.
11.75
119.90
120.00
120.10
120.20
120.30

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Obeserving closed season for rabbit fish, Siganus canaliculatus
all gears
60
50
)
g
k
( 40
h
t
c
a
c 30
ds
ni 20
i
ga
S
10
0
0
4 04 04 04 04 04 04 04 04
0
4 04 04 04 04 04 04 04 04
0
4 04 04 04 04 04 04 04 04
1/ 2/ 3/ 4/ 5/ 6/ 7/ 8/ 9/
1/ 2/ 3/ 4/ 5/ 6/ 7/ 8/ 9/
1/ 2/ 3/ 4/ 5/ 6/ 7/ 8/ 9/
5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 10/04 11/04 12/04 13/04 14/04 15/04 16/04 17/04 18/04 19/04 20/04 21/04 22/04 23/04 24/04 25/04 26/04 27/04 28/04 29/04 30/04 31/04
1
0
/
0
4
1
1
/
0
4
1
2
/
0
4
1
3
/
0
4
1
4
/
0
4
1
5
/
0
4
1
6
/
0
4
1
7
/
0
4
1
8
/
0
4
1
9
/
0
4
2
0
/
0
4
2
1
/
0
4
2
2
/
0
4
2
3
/
0
4
2
4
/
0
4
2
5
/
0
4
2
6
/
0
4
2
7
/
0
4
2
8
/
0
4
2
9
/
0
4
3
0
/
0
4
1
0
/
0
4
1
1
/
0
4
1
2
/
0
4
1
3
/
0
4
1
4
/
0
4
1
5
/
0
4
1
6
/
0
4
1
7
/
0
4
1
8
/
0
4
1
9
/
0
4
2
0
/
0
4
2
1
/
0
4
2
2
/
0
4
2
3
/
0
4
2
4
/
0
4
2
5
/
0
4
2
6
/
0
4
2
7
/
0
4
2
8
/
0
4
2
9
/
0
4
3
0
/
0
4
3
1
/
0
4
5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 5/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 6/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/ 7/
date
new moon
Catch monitoring data from various gears catching rabbit fish in
Danajon Bank from May to July 2004

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
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Major seagrass areas
Closed Season:
In seagrass areas
4th, 5th, 6th nights
after the new moon
March, April & May

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
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Closed season for red grouper, Plectropomus leopardus
Lm
500g - 1,000g
2 - 4 years old
Immature
Super spawners
Length frequency distribution of Plectropomus leopardus in
Calamianes in 1998 (Mamauag et al. 2002)

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
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Ban on harvest of berried lobster
Panulirus larva, (A) Stage I and (B) Stage IX

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
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Alternative sampling gears
· Beach seine
· Push net
· Fry gathering net

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Beach seine

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
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Push net

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
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Fry net

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
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Catch of beach seine

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Catch of push net

REVERSING ENVIRONMENTAL DEGRADATION TRENDS
IN THE SOUTH CHINA SEA AND GULF OF THAILAND
WWW.UNEPSCS.ORG
Species of interest
Tuna
Scombrids
Carangids
Sardines