Species and Size Composition of Push Net Landings and Density of ...
Species and Size Composition of Push Net Landings and Density of ...
Species and Size Composition of Push Net Landings and Density of ...
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Southeast Asian fisheries development centre<br />
(SEAFDEC)<br />
GROUP PRACTICAL REPORT<br />
(16-31 May, 2007)<br />
Presented by: Pham Quoc Huy<br />
Dao Duy Thu
Object<br />
Practicing the learned lessons from training (fish(<br />
eggs <strong>and</strong> larvae sampling <strong>and</strong> identification techniques,<br />
Flow-meter calibration, fishery st<strong>and</strong>ardization…)<br />
Time survey<br />
Juvenile fishes- <strong>Push</strong>ed net boat survey at night 23, May<br />
2007<br />
Fish eggs <strong>and</strong> larvae- Bongo net 25, May 2007 by MV<br />
SEAFDEC 2
Material <strong>and</strong> methods<br />
• <strong>Push</strong>ed net survey<br />
• Bongo net survey<br />
• Some used equations<br />
– S- opened mouth- net area<br />
(m2)<br />
– C- calibration factor (r/m(<br />
r/m)<br />
– N- number in flow meter<br />
– V -Volume <strong>of</strong> water<br />
through the net (m3)<br />
– A- number <strong>of</strong> collected fish<br />
larvae by bongo net<br />
– D- fish larvae density<br />
(ind./1000m3)<br />
V =<br />
D =<br />
S<br />
c<br />
* N<br />
1000*a<br />
V
Results<br />
• Juvenile fishes composition<br />
Yields/h (gr)<br />
80000<br />
70000<br />
60000<br />
50000<br />
40000<br />
30000<br />
20000<br />
10000<br />
0<br />
Fishes Shrimps Mantis shrimps Squids<br />
Secutor indisiator<br />
43%<br />
Carangidae<br />
7%<br />
Engraulidae<br />
4%<br />
Siganus<br />
canaliculatus<br />
15%<br />
Scienidae<br />
7%<br />
Leiognathidae<br />
19%<br />
Clupeidae<br />
5%
Results<br />
• Length frequency <strong>of</strong> major juvenile fishes<br />
4<br />
Engraulidae n = 12, W = 2.5g<br />
3<br />
Ind.<br />
2<br />
1<br />
0<br />
39 40 41 42 43 45 46 48 50<br />
SL(mm)<br />
Clupeidae n = 14, W = 2.9g<br />
4<br />
3<br />
Ind.<br />
2<br />
1<br />
0<br />
52 55 56 57 60 62 63 66 68<br />
SL(m m )
Results<br />
• Fish eggs <strong>and</strong> larvae<br />
No <strong>of</strong><br />
individuals/sample<br />
No <strong>of</strong><br />
families/sample<br />
<strong>Density</strong><br />
(inds./1000m3)<br />
Larvae<br />
249<br />
9<br />
1457<br />
Eggs<br />
375<br />
1<br />
2194
Results<br />
• Fish larva percentage<br />
Engraulidae<br />
71.9%<br />
Cangidae<br />
8.0%<br />
Monacanthidae<br />
0.4%<br />
Bothidae<br />
2.8%<br />
Callionymidae<br />
7.2% Terapontidae<br />
0.8%<br />
Gobiidae<br />
4.8%<br />
Apogonnidae<br />
1.2%<br />
Unknown<br />
2.4%<br />
Scorpaenidae<br />
0.4%
Results<br />
• Fish egg percentage<br />
Unknown<br />
10.7%<br />
Engraulidae<br />
89.3%
Discussion<br />
Challenges<br />
• Lack <strong>of</strong> fishery research equipments<br />
• Low <strong>of</strong> knowledge on early life fishes identification<br />
• Un-updated data annually on fishery resources,<br />
especially fish larvae <strong>and</strong> juveniles<br />
Needs<br />
• Fishery techniques exchanges via training, workshop,<br />
focus on fish larvae <strong>and</strong> juvenile<br />
• Collaborating within regional countries on fishery<br />
resources surveys <strong>and</strong> assessments<br />
• Funds for fisheries research programs/projects<br />
…?...
Thank you!!!
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