Proceedings of the First Technical Seminar on Marine Fishery Resources Survey in the South China Sea, Area I: Gulf of Thailand and Peninsular Malaysia

Biomass Estimation by Hydro-acoustic Methods in the Gulf of Thailand and Peninsular Malaysia

1999-01-01T00:00:00Z

Biomass Estimation by Hydro-acoustic Methods in the Gulf of Thailand and Peninsular Malaysia Theparoonrat, Yuttana; Seakow, Suvimon; Seurungreong, Siriporn The abundance of fisheries resources and their structure in the Gulf of Thailand and East coast of Peninsular Malaysia were investigated during the SEAFDEC Collaborative Research Survey. Hydro-acoustic surveying using a scientific echo sounder model FQ-70 was conducted to estimate the fish abundance and biomass. Two survey cruises were carried out by M.V.SEAFDEC during the pre and post-northeast monsoon seasons. The scientific echo-sounder was equipped with an echointegrator and two quasi-ideal beam transducers with operating frequencies of 50 and 200 kHz. The volume back scattering strength (SV) of the fish schools were collected from the layer of water at a depth from 10 m to the bottom along the track of survey cruise. The estimated biomass measured by high frequency shows clearly that a high concentration is observed at the upper and middle part of the Gulf of Thailand and the boarder area between Thailand and Malaysia waters during the pre-northeast monsoon season. Whereas, high biomass concentration shows only in the middle part of the Gulf of Thailand during the post-northeast monsoon season.

Multi-species Fish Stock Assessment by Acoustic Method in the South China Sea Area I: Gulf of Thailand and East Coast of Peninsular Malaysia

1999-01-01T00:00:00Z

Multi-species Fish Stock Assessment by Acoustic Method in the South China Sea Area I: Gulf of Thailand and East Coast of Peninsular Malaysia Gambang, Albert Chuan; Rajali, Hadil bin; Hassan, Raja Bidin bin Raja; Ali, Rosidi bin; Shiomi, Kunimune; Fujiwara, Shunji; Basir, Shamusudin bin Acoustic resource surveys were conducted by M/V SEAFDEC in the Gulf of Thailand and off the east coast of Peninsular Malaysia from September 5 to 28, 1995 for pre-NE monsoon season and from April 24 to May 17, 1996 for post-NE monsoon season, using the scientific echosounder FQ-70 (Furuno Electric Co.). Collected raw values of backscattering strength (SV) from the 200 kHz were carefully corrected and filtered to eliminate the influence of plankton. These corrected SV values were classified into pelagic and demersal fish, and were used to estimate the biomass of pelagic and demersal multispecies fish. Biomass of pelagic and demersal fish for each season was only estimated in the east coast of Peninsular Malaysia within Malaysian EEZ waters due to the availability of previous fisheries statistics and biological data. Dominant species were selected based on the fisheries statistics and landing place survey. Length (L) and weight were obtained from previous literatures. Target strength (TS) of these dominant species were calculated as TS =20 log (L) -66. The distribution of the SV values for pelagic fish showed a distinct difference between preand post- monsoon seasons. Greater concentrations of SVs were observed from offshore compared to the nearshore waters in pre-monsoon season. The distribution for the demersal fish showed that there was no clear difference between pre- and post-monsoon. The estimated biomass of multi-species fish off the east coast of Peninsular Malaysia within Malaysian EEZ for the pre-and post-monsoon seasons was 4.4x10⁵ tonnes (2.3x10⁵ tonnes of pelagic fish and 2.1x 10⁵ tonnes of demersal fish) and 3.1x10⁵ tonnes (1.9x10⁵ tonnes of pelagic fish and 1.2x 10⁵ tonnes of demersal fish), respectively.

Microplankton (including dinoflagellate and foraminifera) in the South China Sea, Area I: Gulf of Thailand and Peninsular Malaysia

1999-01-01T00:00:00Z

Microplankton (including dinoflagellate and foraminifera) in the South China Sea, Area I: Gulf of Thailand and Peninsular Malaysia Shamsudin, Lokman; Yasin, Abdul Hamid; Razak, Solahudin Abdul; Yusoff, Mohd Shukri Joint collaborative research surveys in the Gulf of Thailand and the South China Sea around the east coast of Peninsular Malaysia during the pre northeast monsoon (4 September - 4 October, 1995) and the post northeast monsoon (24 April - 17 May, 1996) periods were carried out on board the MV SEAFDEC. The microplankton from the sampling stations consisted of more than 205 taxa consisting predominantly of blue green algae (2 species), diatoms (> 120 species), dinoflagellates (> 80 species) and microzooplankton (> 30 groups). The dominant diatom species comprised of Chaetoceros lorenzianum,C. coastatum, Thalassionema frauenfeldii, Skeletonema costatum, Pleurosigma elongatum, Bacteriastrum comosun, Bacillaria paxillifera, Coscinodiscus jonesianus and Rhizosolenia calcar-avis. The genera Chaetoceros, Rhizosolenia, Coscinodiscus, Bacteriastrum and Ceratium were found to contain a wide range of species. Skeletonema bloom (1.12 x 106/m³; 47% of the total cell count) occurred around the Johore waters of the South China Sea. Dinoflagellate was also present during the premonsoon period, especially in offshore waters of the Gulf of Thailand and Terengganu nearshore waters of the South China Sea. The microzooplankton consisted of more than 30 species dominated by copepod nauplii while the foraminifera consisted mainly of the Globigerina species. The diversity index (H) and evenness index (J) values were usually high at stations near to the coast.

Distribution of Dinoflagellate Cysts in the Surface Sediment of the South China Sea, Area I: Gulf of Thailand and East Coast of Peninsular Malaysia

1999-01-01T00:00:00Z

Distribution of Dinoflagellate Cysts in the Surface Sediment of the South China Sea, Area I: Gulf of Thailand and East Coast of Peninsular Malaysia Lirdwitayaprasit, Thaithaworn To obtain more information on the distribution of dinoflagellate cysts in Thai and Malaysian waters, the surface sediment samples of 48 stations in the Gulf of Thailand and the east coast of Peninsular Malaysia were collected by M.V. SEAFDEC during the research cruise in September 1995 and repeated again in April 1996. Cysts of 20 species belonging to Goniolacoid, Tuberculodinioid and Peridinioid were found in the surface sediments collected from both cruises. Spiniferites spp. (=Gonyaulax spp.) were the dominant cyst in Thai and Malaysian waters. No cysts of harmful species were observed during this study.