LAPORAN TAHUNAN 1990 (ANNUAL REPORT FOR 1990)

INSTITUT PENYELIDlKAN PERIKANAN, (FISHERIES RESEARCH INSTITUTE)

11700 GELUGQR, P. PINANG.

JABATAN PERIKANAN, (DEPARTMENT OF FISHERIES)

KEMENTERIAN PERTANIAN, (MINISTRY OF AGRICULTURE)

MALAYSIA.

SEITEMBER 1991.

1.

2 .

3 .

4 .

5.

6.

7 .

8.

INTRODUCTION

1.1 Organization

1.2 Posts

CONTENTS

1.3 Research facilities

RESEARCH AND INVESTIGATIONS

PAGE

1

7

8

9

10

2.1 Fisheries Research Institute, Glugor, Penang 10

2.2 Nat. Prawn Fry Production & Research Centre, Kedah 12

2.3 Freshwater Fisheries Research Centre, Malacca 13

2.4 Brackishwater Aquaculture Research Centre, Johor 14

2.5 Marine Fish Resource Research Centre, Terengganu 15

2.6 Marine Fisheries Research Centre, Sarawak. 16

OBSERVATIONS AND RESULTS

3.1 Fisheries Research Institute, Glugor, Penang 17

3.2 Nat. Prawn Fry Production & Research Centre, Kedah 55

3.3 Freshwater Fisheries Research Centre, Malacca 74

3.4 Brackishwater Aquaculture Research Centre, Johor 89

3.5 Marine Fish Resource Research Centre, Terengganu 97

3.6 Marine Fisheries Research Centre, Sarawak. 112

MAINTENANCE & DEPLOYMENT OF RESEARCH VESSELS

PUBLICATIONS & REPORTS

NEW STAFF/TRANSFERS ETC.

VISITS/VISITORS

MEETINGS/SEMINARS/LECTURES/TRAINING COURSES

APPENDIX 1

122

126

134

136

141

155

1. INTRODUCTION

Fisheries

FISHERIES RESEARCH INSTITUTE

DEPARTMENT OF FISHERIES

MINISTRY OF AGRICULTURE MALAYSIA

11700 GELUGOR, PENANG

ANNUAL REPORT FOR 1990

research and development continued to make

considerable progress during the year 1990. In the field of

aquaculture research, several significant advancements were

achieved in the breeding andlarviculture technology for several

commercially important species. These include the successes in

the area of marine finfish propagation, including the first ever

successful induced spawning of snapper (Lutjanus sp). The

subsequent larviculture resulted in the production of several

hundred stockable fry. Further refinements in the larviculture

of the grouper, Epinephelus suillus produced over 9,000 stockable

fry. Compared to the single fry produced in 1989, the recent

production figure marked a major progress. The success in the

isolation and culture of a dwarfrotifer as live food for the

small early fish larvae appears to be a major contributing factor

for the fish larviculture success. However while the foundation

for the mass production of marine finfish fry has been

considerably strengthened, further advancements in larviculture

1

technology are needed before the fry of both the grouper and the

snapper can be commercially produced.

In the area of prawn/shrimp farming, the production of

postlarvae / juveniles again reached a new record of 140 million.

with the hatchery technolgy for both marine shrimps and the

freshwater prawn well established, the scope of work for

crustacean aquaculture was widened to encompass the mangrove /

mud crab (Scylla serrata), and the swimming crab (Portunus

pelagicus). Results so far indicate that the mass larviculture

of the swimming crab appears to be feasible. For the mangrove

crab which is presently the preferred species for crab farming,

further improvements in rearing technique are required to

overcome heavy mortalities, due apparently to a large extent to

the cannibalistic habit of the species.

In the field of mollusc culture, the Fisheries Research

Institute - with the assistance of the Bay of Bengal Programme

(BOBP) - made significant progress in the development of oyster

culture in the country during the year. Suitable techniq~es and

sites have been determined for the spat collection,

transplantation and culture of Crassostrea iredalei and ~

belcheri, with the participation of fisherfolk at various

localities.

In the area of freshwater fish research, the African

catfish,

introduced

Clarias lazera (=gariepinus), which has recently

into the country, was successfully bred and

2

been

mass

produced. As this species of catfish shows a much better growth

rate and are also much hardier than the local Clarias species,

its successful propagation to ensure an adequate supply of

stockable fry would lead to the expansion of Clarias catfish

farming in the country. In the freshwater aquarium fish breeding

programme, the number of fish species that could be bred in

captivity has been increased to 26.

To speed up the identification of potential areas for

aquaculture development in the country, the use of computerised

geographical information system (GIS) has been widened.

In the field of fisheries resource research, a demersal fish

resource survey was successfully earried out on the east coast

of Peninsular Malaysia. The survey data together with the

monitoring of commercial landings indicated that the density of

the demersal fish stock in the area had remained quite stable.

This could be attributed to the effectiveness of the various

conservation measures taken by the Department of Fisheries.

On the west coast of P. Malaysia, a prawn trawling survey

was successfully conducted during the year. The grounds off the

Perak coast yielded higher catch-rates than areas in Kedah and

Perlis. The dominant species were Metapenaeus lysianassa and

Parapeneopsis hardwickii.

Fish resource studies on the west coast of P. Malaysia

included investigations on the effort and landings of'~ukat Kenka

3

2-Bot" (2-boat Danish seines) off Perak. The exploitation rate

for coastal penaeid prawns has been found to be relatively high

but the catches of the boats appear to be quite stable, possibly

as a result of rapid recruitment of the stocks.

Resource studies also included monitoring of the landings of

fish purse-seiners using spotlights and lures, on the west coast

of P. Malaysia. As most of the purse-seiners have installed

spotlights to increase their fishing efficiency, closer

monitoring of the resource is necessary to prevent

exploitation.

over-

In the area of fishing gear,development, the Research Centre

at Bintawa, Sarawak carried out trials - using K.K. MANCHONG

on the use of rubber disc ground rope for trawling on uneven or

rocky grounds. This type of ground rope proved so successful

that it was soon adopted by several offshore commercial trawlers

with minor modifications. It is likely that the impressive

catches of these vessels would convince other fishermen to follow

suit.

Under the aquatic ecology research programme, the

artificial reef project studied the effectiveness of new reefs

made of PVC pipes, specially designed concrete blocks and a

combination of PVC and concrete blocks. Regular monitoring was

conducted to assess the fish population, rate of encrustation and

the structural integrity of the reefs. Concrete appeared to be

the most cost effective material but more studies need to be

4

carried out to determine the cost-effectiveness and the most

suitable method of reef construction for different reef

materials.

Monitoring of heavy metal and pesticide levels in fish and

shellfish from the coastal and inland waters generally indicates

that fisheries products from our aquatic environment are

relatively free from such contaminants and do not pose any health

hazard to the consumers.

The occasional high bacterial count for certain cultured

shellfish is however a cause for concern, hence the need for

depuration. The services of 2 FAO consultants were sought to

further improve on the existing laboratory depuration unit and

design

Technical

a commercial

assistance

system

will be

for large-volume

provided to LKIM

depuration.

in the

establishment of a suitable commercial depuration facility.

At the

reported in

Kuala Terengganu Research

the rearing of newly hatched

branch, success was

leatherback turtles.

This work, carried ou~ under the Turtle Conservaton Programme

started in September 1990, has also set a world record in the

keeping of baby leatherbacks in captivity. From an initial

weight of 38 gm, the baby turtles have since grown to over 700 gm

each and studies are in progress.

In 1990, the operating cost of running the Institute,

5

together with its following branches (Appendix 1):

i) Brackishwater Aquaculture Research Centre, Gelang Patah, Johorei

ii)

iii)

Marine Fish Resource Terengganui

Research Centre,

Freshwater Fisheries Research Centre, Batu Malacca andi

Chendering,

Berendam,

iv) National Prawn Fry Production & Research Centre, Kg. Pulau Sayak, Kedahi

amounted to slightly over $5.4 million. occasional difficulties

were encountered with the operating budget and it is hoped that

there will be an appropriate increase of operating funds in

future.

Research and development expenditure for the year in the

following projects, totalled approximately $3 million:

Nat. Prawn Fry Production & Res. Centre, Kedah $322,003

Assessment of Coastal Fish Resources $247,700

Artificial Reef Development $91,542

Assessment of Offshore Fish Resources $321,893

Aquaculture Research $992,684

Handling of Fish Products $121,239

Production Economics $94,493

Mollusc Culture $701,524

Turtle Conservation $74,994

Total R&D Expenditure = $2,954,719 =====:::::====

6

1.1 ORGANIZATION

The Institute comprises 3 research sections, viz. Resource,

Aquatic Ecology and Aquaculture (Appendix 2).

The Resource Section consists of the Demersal, Pelagic and

Fishing Gear Technology units - all based in Glugor - and the

Marine Fish Resource Research Centre, situated in Chendering,

Terengganu. The Marine Fisheries Research Centre, located in

Bintawa, Sarawak, also concentrates on resource studies, thought

some ef~ort is directed towards artificial reef development and

brackishwater aquaculture research ..

The Aquatic Ecology section includes the Conservation and

Pollution Units, both based in Glugor, Penang. It works closely

with the Institute's branches in Chendering, Terengganu and

Bintawa, Sarawak, on the development of artificial reefs and

marine parks.

The Aquaculture section consists of the Mariculture unit in

Glugor, Penang; the Freshwater Fish Research Centre in Batu

Berendam, Malaccai the Brackishwater Aquaculture Research Centre

in Gelang Patah, Johore and the National Prawn Fry Production and

Research Centre in Kg. Pulau Sayak, Kedah.

The Institute also has a research component in the

Department's Marine Finfish Fry Production Centre at Tanjung

Demong, Terengganu where research and development on the

artificial propagation of Lates calcarifer, Epinephelus sp. and

Lutjanus sp. has made further progress.

7

1.2 POSTS

In 1990, the Institute had a total of 499 permanent posts,

the breakdown of which is as follows:

Group A Group B Group C Group D Total

Glugor 39 8 48 74 169

P.Sayak 12 5 14 42 73

B.Berendam 12 9 27 56 104

G.Patah 5 2 7 24 38

Chendering 4 11 15 30

Bintawa 11 31 43 85

TOTAL 83 24 138 254 499

However not all the posts were filled. Several staff

members were away on long study leave and available staff had to

be redeployed in order to enable projects to be implemented as

smoothly as possible. The problem arising from lack of suitable

crew members for the various research vessels was often quite

critical as the job could not be done by unqualified personnel.

This was alleviated to some extent by carrying out some

investigations at sea on board commercial fishing vessels. To

ensure smooth implementation of all the research projects, it is

hoped that all existing vacancies of posts in the various

categories will be filled as soon as possible.

8

1.3 RESEARCH FACILITIES

There has been considerable upgrading of research facilities

in all branches of the Institute following the completion of

development projects and the provision of adequate funds under

the IRPA programme.

The completion and operation.of the Phase Two Extension to

the Marine Finfish Fry Producton Centre in Tanjung Demong,

Terengganu, substantially increased the capacity of the Centre in

the area of marine finfish propagation. The construction of a

new 4-storey building in Chendering, Terengganu to be completed

in 1991, was expected to provide adequate space for the Marine

Fish Resource Research Centre, earlier temporarily housed in 2

rented shoplots. In Penang the completion of the research cum

adminstrative complex at Batu Maung should result in considerable

modernization of facilities for fisheries research in the coming

years.

Besides the shore-based facilities, there are several

research vessels available for resource assessment, exploratory

fishing and fishing gear development. The vessels are also

deployed for artificial reef construction and monitoring, and

pollution studies. These include K. K. MERSUJI, K.K. PELALING,

K.K. KERAPU and K.K. JENAHAK which are based in G~ugor, Penang;

K.K. SENANGIN in Chemdering, K.K. MANCHONG and K.K. MALONG in

Kuching, Sarawak. Full deployment of the vessels for the year

was however handicapped by crew shortage.

9

2. RESEARCH AND INVESTIGATIONS

The overall research programme is geared towards the proper

development and management of the fisheries sector (including

aquaculture), in line with Government policies and in particular,

the National Agriculture Policy.

The main research projects carried out by the officers of

the various sections/centres of the Institute during 1990 were as

follows:

2.1

(a)

2.1.1

2.1. 2

2.1. 3

2.1. 4

2.1.5

2.1. 6

2.1.7

Fisheries Research Institute, Penang:

Resource Research

Monitoring and analysis of landings and composition of commercial fish purse-seine boats

, Phaik Ean) .

Monitoring and analysis of landings and composition of commercial anchovy purse-seine (Chee Phaik Ean).

catch (Chee

catch boats

Biological studies on selected pelagic fish species including tuna (Chee Phaik Ean) .

Demersal fish resource survey in the coastal waters off the east coast of Peninsular Malaysia (Alias b. Man, Lui Yean Pong and Ahmad Adnan b. Nuruddin).

Demersal fish resource survey in the coastal waters off the west coast of Peninsular Malaysia (Ahmad Adnan b. Nuruddin) .

Monitoring and analysis of landings and catch composition of commercial 2-boat Danish seines based in Kuala Kurau, Perak, and biological studies on the dominant prawn species landed (Mohd. Taupek b. Mohd. Nasir and Ibrahim b. Johari).

Monitoring and analysis of landings of carpet (Paphia undulata) at Sungai Batu, Kedah (Mohd. b. Mohd. Nasir and Lui Yean Pong) .

10

clams Taupek

2.1.8

2.1.9

2.1.10

2.1.11

2.1.12

2.1.13

2.1.14

2.1.15

2.1.16

2.1.17

(b)

2.1.18

2.1.19

2.1.20

2.1.21

2.1.22

Prawn resource survey in the coastal waters of the west coast of Peninsular Malaysia (Abu Talib b. Ahmad).

Experimental prawn tagging in the coastal waters of northern Perak (Abu Talib b. Ahmad).

studies on the recruitment of the penaeid prawn Penaeus merguiensis in the estuarine waters of Kuala Sepetang, Perak (Abu Talib b. Ahmad, Ahmad Adnan b. Nuruddin and Lui Yean Pong).

Monitoring and analysis of landings and catch composition of commercial trawl boats (Mahyam bt. Mohd Isa) .

Biological study on Sepia aculeata landed at Kuala Kedah, Kedah (Samsudin b. Basir).

Monitoring and analysis of landings and catch composition of Sepioteuthis lessoniana portable traps (Samsudin b. Basir and Rosidi b. Ali).

Experimental trials with pair trawl net (Rosidi b. Ali and Ibrahim b. Johari).

Comparative studies on the efficiency of 2-seam, 4-seam and 6-seam trawl nets (Rosidi b. Ali).

Comparative study on the design and efficiency of crab traps (Rosidi b. Ali and Ibrahim b. Johari).

Monitoring and analysis of fishing trials conducted jointly with the Extension and Education Division of the Department of Fisheries, Malaysia (Rosidi b. Ali and Ibrahim b. Johari).

Aquaculture Research

Larviculture and nursing of fry of and Epinephelus suillus (Ali Awang, Ramli Saad) .

Lates calcarifer Mahdom Ibrahim,

Broodstock maturation and spawning of Epinephelus sp. (Ali Awang, Mahdom Ibrahim, Ramli Saad).

Culture of live food organisms (Ali Awang, Ng Fong Oon) .

Cockle transplantation and culture (Ng Fong Oon, Kamal Zaman, Devakie Nair).

Mussel transplantation and culture (Ng Fong Oon, Kamal Zaman, Devakie Nair).

11

2.1.23

2.1.24

2.1.25

2.1.26

(c)

2.1.27

2.1.28

2.1.29

2.1.30

2.1.31

2.1.32

2.1.33

Oyster transplantation and culture (Ng Fong Oon, Kamal Zaman, Devakie Nair, Ong Kah Sin) .

Fish health and disease (Md. Akhir Arshad, Choo Poh Sze) .

Seaweed culture (Ramli Saad, Choo Poh Sze) .

Technical support for coastal finfish hatchery operations in Tanjung Demong, Terengganu (Munir Hj. Nawi, Nik Razali Nik Lah, Ali Awang).

Ecology Research

Management in Artificial Reef Development & Research (Abdul Razak Latun, Mohd. Pauzi Abdullah and Wan Portiah Hamzah) .

study on the Coral Reef Ecosystem - Marine Parks (Mohd. Pauzi Abdullah and Abdul Razak Latun) .

Study on the Seagrass Ecosystem (Mohd. Pauzi Abdullah and Abdul Razak Latun) .

Cockle Depuration Studies (Wan Portiah Hamzah and Velu Murugan) .

Monitoring of heavy metals in fish shellfish and sediment (Shahunthala Devi and Wan Portiah Hamzah) .

Analyses of pesticides in shellfish and freshwater fish (Shahunthala Devi and Wan Portiah Hamzah).

Fish Kills in Inland & Coastal Waters & Water Monitoring (Shahunthala Devi, Velu Murugan Portiah Hamzah) .

Quality and Wan

2.2 National Prawn Fry Production « R,esearch Centre, Kedah

2.2.1

2.2.2

2.2.3

2.2.4

Culture of live food organisms (Faazaz Abd Latiff and Fariduddin Othman).

Maturation studies of Penaeus monodon (S. Makinouchi and V. Palanisamy).

~ulture and maintenance of pond grown broodstock of £. monodon (K.Subramaniam, Liong pit Chong and Safiah Sayuti).

Larviculture of marine shrimp (V. Palanisamy, Faazaz Abd Latiff, Rashidah Mat Resat and Muhamad Hatta Hj. Mahmud) .

12

2.2.5

2.2.6

2.2.7

2.2.8

2.2.9

2.2.10

Larviculture of the Giant Malaysian Freshwater Prawn Macrobrachium rosenbergii (Yaakob Ahmad and Zainoddin Jamari) .

LarJiculture of swimming crab and mud crab (Zainuddin Jamari and Che Utama Che Musa).

Nursery management and fry distribution (Othman Muhamad and Muhamad Hatta Hj Mahmud).

Open water stocking of shrimp/prawn/crab fries (Othman Muhamad and Liong Pit Chong).

Feed formulation (Che Utama Che Musa and Zainoddin Jamari) .

Pathology and water quality studies (V. Palanisamy, Faazaz Abd. Latiff and Liong pit Chong).

2.2.11 Training programme of the Centre.

2.3 Freshwater Fisheries Research centre, Melaka

2.3.1 Breeding of indigenous fishes (Ahmad Ashhar Othman, Mohamad Zaini Suleiman, Haron Abdullah, Saadon Kasmon) .

2.3.2 Breeding of exotic fishes (Ahmad Ashhar Othman, Mohamad Zaini Suleiman, Haron Abdullah, Saadon b. Kasmon).

2.3.3

2.3.4

2.3.5

2.3.6

2.3.7

Breeding of catfishes (Thalathiah Saidin, Taat) .

Ibrahim

Genetics and breeding of Tilapia (Chuah Hean Peng, Nor Azman Abd. Ghani).

Breeding and culture of ornamental fishes (Jamaludin Ibrahim, Chuah Hean Peng, Nor Azman Abd. Ghani).

Pond-culture of the Red Tilapia (S. Pathmasothy).

Pond-culture of prawns - Udang Galah (Suhairi Alimon, Misri Samingin).

2.3.8 Pond-culture of Sea Bass - Siakap (S. Pathmasothy).

2.3.9 Culture of live-feed (Siti Azamah Mustapha).

2.3.10 Fish nutrition (S. Pathmasothy, Maznah Othman).

2.3.11 Fish disease diagnosis and control (Siti Abdullah) .. -

13

Zahrah

2.3.12

2.3.13

2.3.14

2.4

2.4.1

2.4.2

2.4.3

2.4.4

2.4.5

2.4.6

2.4.7

2.4.8

2.4.9

2.4.10

2.4.11

2.4.12

2.4.13

Fishery development of reservoirs (Zulkafli Rashid, Zahari Awang) .

Abd.

National Agriculture Park, Shah Alam (Zulkafli Abd. Rashid, Zahari Awang).

Water quality in aquaculture (Maznah Othman, Zahari Awang) .

Brackishwater Aquaculture Research Centre, Johor

Kajian Menentukan Peringkat Umur dan Kadar semaian Benih Yang optima Untuk Ternakan Intensif dan Separa Intensif Udang Putih (Penaeus merguiensis) Dalam Kolam.

Kajian Ternakan intensif' .

Udang Harimau Secara 'Super-

Kajian Ternakan Pembesaran Ikan Siakap Dalam Kolam Dengan Makanan Pelet Rumusan Pusat.

Ujian Terhadap Ternakan Ikan Tilapia Merah Di Dalam Kolam.

Kajian Perumusan Makanan Untuk Udang Harimau (Penaeus monodon) Di Peringkat Asohan.

Ujian Perumusan Makanan Udang merguiensis) Peringkat 'Grower'.

Putih (Penaeus

Kajian Perumusan Makanan Untuk Ikan Tilapia merah.

Kajian Pengawasan Parameter Mutu Air Sungai Gelang Patah.

Kajian Terhadap Parameter Mutu Air dan Tanah Yang Optima Untuk Ternakan Udang dan Ikan Laut Di Kolam.

Kajian Kesan Rekabentuk Kolam Terhadap Masalah Asid Sulfide

Kajian Pengawasan Jenis-jenis Penyakit dan Paras it IkanjUdang Airpayau Serta Rawatan dan Pengawalannya.

Kajian Ekonomi Pengeluaran Perbandingan Ekonomi Di antara Kolam Yang Menggunakan sistem Pam Dengan sistem Pasang-Surut.

Perbandingan Kesesuaian dan Ekonomi Di Antara Kolam Berdasar Pasir Dengan Lumpur Untuk Ternakan Udang.

14

2.5

2.5.1

2.5.2

2.5.3

2.5.4

2.5.5

2.5.6

2.5.7

2.5.8

2.5.9

2.5.10

2.5.11

2.5.12

2.5.13

2.5.14

Marine Fish Resource Research Centre, Terengganu (Pusat Penye1idikan Sumber Ikan Marin, Terengganu)

Kajian Migrasi Tuna di Laut China Selatan (Raja bin Raja Hassan).

Bidin

Kajian Biologi Tuna (Raja Bidin bin Raja Hassan, Kamar-ruddin bin Ibrahim).

Kajian Penggunaan Payao dalam Perikanan Rekreasi (Raja Bidin bin Raja Hassan) .

Kajian Sumber Ikan Hassan) .

Rekreasi (Raja Bidin bin Raja

Kajian Penetapan Tahap Pengekploitasian Stok Bidin bin Raja Hassan, Raja Mohammad Noordin bin Omar, Che Omar bin Mat Hussin, Azman bin Said) .

Kajian Pendaratan dan Komposisi Tangkapan Ikan bin Said) .

(Raja Raja

(Azman

Kajian Kelompok Mohammad Ibrahim,

Penggunaan Remote Sensing Ikan Pelajik (Abdul Hamid

Noordin bin Raja Omar, Raja Bidin bin Raja Hassan).

dalam Mengesan bin Yassin, Raja

Kamarruddin bin

Kajian Pembangunan Sumber Berpotensi (Sukarno bin Wagiman, Che Omar bin Mat Hussin).

Kajian Migrasi Penyu Belimbing Menggunakan' Teknologi Satelit (Sukarno bin Wagiman, Raja Mohammad Noordin bin Raja Omar, Che Omar bin Mat Hussin).

Kajian Penetasan In situ Telur Penyu Belimbing (Sukarno bin Wagiman, Che Omar bin Mat Hussin, Nadzri bin Seman) .

Kajian Kesan Aktiviti Perikanan di Perairan Santuari Penyu Rantau Abang (Sukarno bin Wagiman, Che Omar bin Mat Hussin).

Kajian Penandaan Penyu Laut (Che Omar bin Mat Hussin).

Kajian Pengasuhan Anak Penyu Belimbing (Kamarruddin bin Ibrahim, Azman bin Said) .

Projek Tukun Tiruan ADB di Pulau Perhentian (Raja Mohammad Noordin bin Raja Omar, Sukarno bin Wagiman, Raja Bidin bin Raja Hassan, Che Omar bin Mat Hussin, Azman bin Said).

15

2.5.15

2.5.16

2.5.17

2.5.18

2.6

2.6.1

2.6.2

2.6.3

2.6.4

2.6.5

2.6.6

2.6.7

2.6.8

Projek Penyelidikan di Mohammad Noordin bin Ibrahim, Sukarno bin Hassan) .

Taman Laut Pulau Redang Raja Omar, Kamarruddin

Wagiman, Raja Bidin bin

Kajian Inventori Kima di Pulau Kapas dan Pulau (Che Omar bin Mat Hussin, Sukarno bin wagiman, bin Ali).

(Raja bin

Raja

Gumia Ahmad

Projek Usahasama Jabatan Perikanan-IPTP: Pendaratan Ikan Tuna Kecil di Terengganu Darul Iman (Raja Bidin bin Raja Hassan, Kamarruddin bin Ibrahim).

Projek Usahasama PPSIM-IPP: Kajian Sumber Sotong Mengabang di Pulau Kapas (PPSIM: Raja Bidin bin Raja Hassan, Raja 'Mohammad Noordin bin Raja Omari IPP: Samsuddin bin Basir) .

Marine Fisheries Research Centre, Sarawak

Trawl trials with commercial vessel (Albert Chuan Gambang and Mikio Wakamatsu).

Neretic tuna landings in Sarawak (Richard Rumpet) .

continuation work on the artificial propagation of terubok (Tenualosa toli) and other associated projects ( Yong Ai Hua).

Coastal prawn resource survey in Sarawak using K.K. Malong (Yong Ai Hua and Sayed Shahabudin Sayed Alwi) .

Artificial reef extension and construction in Sarawak waters (Ismaili Bujang Pit).

Cockle and Mussel culture in Mohidin) .

Sarawak (Mohammed

Aquaculture potential study for Sarawak using GIS and applying criteria for tiger prawn as a standard (Mohammed Mohidin and Pang Suh Cern as members of the study team with staff from PPTAP, Gelang Patah and Extension Section, Sarawak).

Preliminary site feasibility study for a hatchery and growout pond(s) carried out in various parts of Sarawak (Mohammed Mohidin and Pang Suh Cern).

16

3. OBSERVATIONS AND RESULTS

3.1 Fisheries Research Institute, Penang

(a) Resource Research

3.1.1 Monitoring and analysis of landings and catch composition of commercial fish purse-seine boats.

The landings of fish purse-seine boats based at Teluk

Bahang, Penang and Pulau Pangkor, Perak were monitored monthly

during the course of the year.

Teluk Bahang, Penang

Most of the fish purse-seine boats operating from Teluk

Bahang have been fitted with spotlights. A few units operate

occasionally without spotlights.

Very little fishing was performed during the first two

months of 1990 owing to bad weather. As such no data was made

available to the field samplers. Fishing was mainly in

conjunction with spotlights from March onwards and the average

catch per boat per month ranged from 27.63 tons to 35.32 tons for

the first six months of 1990 when catches were observed to be

better. During the second half of 1990, catches were generally

poor except for October and November. Overall the catch rates

observed for the fish purse-seine boats fitted with spotlights

from Teluk Bahang were much better than the average catch rates

of the fish purse-seine boats fishing with lures (tuas) which

ranged from 0.93 tons to 16.16 tons for 1990. Also, only a few

boats fished from the 'tuas'.

17

The boats fishing with 'tuas' caught mainly ikan selayang

(Decapterus spp.), ikan selar (Atule mate), ikan bawal hitam

(Formio niger) and ikan kembung (Rastrelliger spp.), while those

fishing with spotlights landed mainly ikan selayang (Decapterus

spp.), tuna (Euthynnus affinis, Auxis thazard), ikan kembung

(Rastrelliger kanagurta) and ikan bawal hitam (Formio niger).

other species caught by the boats fishing with spotlights

included ikan selar (Atule mate, Selar spp.), ikan cincaru

(Megalaspis cordyla), ikan talang (Scomberoides spp.) and ikan

tamban buluh (Dussumieria spp.).

pulau Pangkor, Perak

The purse-seine boats with spotlights performed better than

those that operated without spotlights (pukat jerut malarn). The

average catch rates obtained by the boats operating with

spotlights ranged from 4.25 tons to 308.56 tons per boat per

month.

Most boats had been fitted with spotlights, thus they had

the option to switch to using spotlights to aggregate fish

whenever the right conditions prevailed. Only a few boats

operated without spotlights. The average catch of the purse-

seine boats operating without spotlights ranged from 3.85 tons to

19.37 tons per boat per month. The purse-seine boats fished

intermittently without the use of spotlights and most boats used

spotlights to aggregate fish whenever they could.

The purse-seine boats operating without spotlights (pukat

jerut malam) at Pulau pangkor caught mainly ikan pelaling

18

(Rastrelliger brachysoma) followed by tuna (Euthynnus affinis

and possibly mixed with Auxis thazard) and lesser quantities of

sardines (Sardinella fimbriata). However, very few boats

operated purse-seines strictly without spotlights; most boats

have now been fitted with spotlights and they switch from one

method to the other whenever the right conditions prevailed . •

The main species caught by the purse-seine boats operating

with spotlights, on the other hand, were mainly ikan kembung

(Rastrelliger kanagurta), tuna (possibly Euthynnus affinis mixed

with Auxis thazard), ikan selayang (Decapterus spp.) and sardines

(Sardinella fimbriata). other species caught by these boats in

lesser quantities were ikan pelaling (~ brachysoma), ikan

cincaru (Megalaspis cordyla) , ikan tenggiri (Scomberomorus spp.)

and ikan tamban buluh (Dussumieria spp.).

3.1.2 Monitoring and analysis of landings and catch composition of commercial anchovy purse-seine boats.

The catches of the anchovy purse-seine boats based at Pulau

Pangkor, Perak and Tanjung Dawai/Sungai Batu, Kedah were

monitored from January to December, 1990.

Pulau Pangkor, Perak

The average catch per boat per month ranged from 4.85 tons

to 47.99 tons per boat per month. The average catch rate

remained high from March to August 1990. The lowest catch rate

of 4.85 tons per boat per month was observed in December 1990.

19

stolephorus spp. contributed between 68% to 98% to the

total catch of the anchovy purse-seine boats based at Pulau

Pangkor. Other species caught were small Sardinella spp.,

Rastrelliger spp. and leiognathids. The dominant species of

Stolephorus caught was observed to be Stolephorus heterolobus.

It was observed that during the months of November and December

1990, there was an increase in the percentage of fish other than

Stolephorus spp.. These were mainly Rastrelliger spp. and

Sardinella spp .. The presence of the young of both these species

possibly indicates the spawning season of these fish.

Tanjung Dawai/Sungai Batu, Kedah

Generally the average catch rate per boat per month obtained

by the purse-seine boats based at Tanjung DawaijSungai Batu had

been high, ranging from 18.73 tons to 40.76 tons. There does not

appear to be a very large variation in the monthly average catch

rate seen over the year at Tanjung DawaijSg. Batu as is seen for

the Pulau Pangkor boats.

Here Stolephorus spp. made up approximately 78% to 97% of

the total catch of the anchovy purse-seine boats. Other species

of fish caught included mainly Rastrelliger spp. and Sardinella

spp. As observed for the pulau Pangkor boats, there was an

increase in the percentage of these two species in the catch of

the anchovy purse-seine boats in November and December 1990.

20

3.1.3 Biological studies on selected pelagic fish species including tuna.

(i) Small pelagics On The west Coast of Peninsular Malaysia

Biological studies on selected species of pelagic fish were

continued at Teluk Bahang, Penang and Pulau Pangkor, Perak. The

species studied included Rastrelliger kanagurta, ~ brachysoma,

Decapterus maruadsi, and the tuna, Euthynnus affinis and Auxis

thazard. It was however found that the landings of tuna were not

as easily sampled because they were not regularly caught.

Length frequency measurements were taken monthly and the

gonadosomatic indices determined for the individual species

caught by each type of purse-seine i.e. purse-seine using

spotlights (pukat jerut berlampu), purse-seine using lures (pukat

jerut tuas) and purse-seine using neither spotlights or lures

(pukat j~rut malam).

Teluk Bahang, Penang

The mean length of Rastrelliger kanagurta and Decapterus

maruadsi caught by the purse-seines using spotlights ranged from

181mm to 198mm and from 125mm to 158mm dorsal extreme length

respectively. Very few fish could be sampled from the boats

fishing with purse-seines using lures because very few of them

fished from the lures.

The highest GSI for both female and male Rastrelliger

kanagurta sampled from the purse-seine boats using spotlights was

observed in April 1990. For Decapterus maruadsi the highest GSI

was seen in July. Thus it is possible that these two fishes

spawn just after these months.

21

Pulau Pangkor, Perak

There does not appear to be a large variation in the mean

sizes of the fish species caught over the months. The mean

length of Rastrelliger kanagurta and Oecapterus maruadsi caught

by the purse-seine boats using spotlights ranged from 198mm to

225mm and 120mm to 173mm, while the mean length of Rastrelliger

brachysoma caught by the 'pukat jerut malam' were between 173mm

and 196mm.

The highest GSI for Rastrelliger brachysoma caught by the

'pukat jerut malam' boats was recorded in March for the female

fish. The male fish did not show such a large variation in the

GSI but just shows a decline after July. It is possible that ~

brachysoma spawns just after April.

(ii) Length Frequency Analysis

Length frequency data obtained for kawakawa, Euthynnus

affinis collected from Kuala Terengganu and the Indian mackerel

Rastrelliger kanagurta collected from Kuala Perlis for 1988 and

1986/1987 respectively were analyzed to yield Loo and the growth

rate K. The results obtained are given below.

species

Euthynnus affinis 65 cm 0.5 cm/year (fork length)

Rastrelliger kanaqurta 29.9 cm 0.65 em/year (total length)

22

Further analysis of the data could be done but certain

irregularities in the data sets required further checking of the

raw data collected. When this is done, a yield per recruit model

for each of the species could be attempted to ascertain the

status of the fishery. Preliminary indications are that both

species are heavily exploited.

3.1. 4 Demersal fish resource survey in the coastal waters off the east coast of Peninsular Malaysia.

A demersal fish resource survey on the east coast of

Peninsular Malaysia was conducted with the research vessel

K.K."MERSUJIII from 20/6/90 to 5/8/90. A total of 60 successful

hauls were completed during the survey. The average catch rate

obtained was 71.6 kg/hr of which 45.5 kg (64%) were commercial

fish and the balance of 26.1 kg (36%) being trash fish. The

average catch rate obtained is the same as that obtained during a

similar survey conducted with the same research vessel in the

same area in 1988 which provided an average catch rate of 72

kg/hr. This indicates that the density of the demersal fish

stock in the area had remained quite stable during the period

between the two surveys.

The dominant species caught were the rays and the squids

which contributed 10% and 7% respectively towards the total

catch. These were followed by the mullids and the nemipterids

which contributed about 5% to the total catch. The priacanthids

and carangids also contributed around 4% to the total catch. The

other species individually contributed less than 4% to the total

catch.

23

The waters off East Johor appeared to the least productive

of the area surveyed. The average catch rate obtained was about

55 kg/hr compared to around 72-75 kg/hr obtained for the waters

off pahang, Terengganu and Kelantan.

3.1.5 Demersal fish resource survey in the coastal waters off the west coast of Peninsular Malaysia.

Due to unforeseen delays, the survey could only be started

in the middle of December and anticipated to end only in early

1991. As the survey is still on-going, the complete survey data

can only be processed and analyzed after its completion in early

1991.

3.1.6 Monitoring and analysis of landings and catch composition of commercial 2-boat Danish seines based in Kuala Kurau, Perak, and biological studies on the dominant prawn species landed.

The monitoring of the catch by the 2-boat Danish seines

based at Kuala Kurau, Perak was continued during the course of

the year. Analysis of the catch data indicates that the average

catch rate obtained by these boats was around 119 kg/trip/fishing

unit. This figure is comparable to the average catch rate of 122

kg/trip/unit obtained in 1988. Penaeid prawn contributed to

about 62% or 74 kg/trip/unit to the total catch, while trash fish

catch averaged around 43 kg/trip/unit (36%). Commercial fish and

mantid shrimps made up the balance of 2% of the total catch.

24

During spring tides, the small-sized prawns caught were

dominated by Parapeneopsis hardwickii and ~ coromandelica, while

the medium-sized prawns were mainly Metapenaeus affinis and ~

sculptilis. However, during neap tides there appear to be a

change in the dominant species caught. The small-sized prawns

were predominantly ~ lysianassa and ~ hardwickii, while the

medium-sized ones were ~ affinis and ~ brevicornis. The

dominant large-sized species caught during the two tides was

Penaeus merguiensis.

Juveniles of commercial species made up the bulk of the

trash fish caught by the 2-boat Danish seines. About 87% by

weight of the total trash fish catch by this fishing gear were

juveniles of commercial fish species.

Preliminary analysis of the length frequency data for some

of the dominant prawn species with ELEFAN indicates that the

exploitation of the prawn resources in the area fished by this

gear has already reached the maximum. The results obtained are

as follows:

Loo K F M E (TL-mm) (fyr)

~ affinis (m) 129 0.65 1. 71 1. 76 0.49 ( f) 162 0.54 1. 53 1. 46 0.51

~ scul12tilis (m) 155 0.60 4.43 1. 59 0.74 (f) 165 0.50 0.47 1. 38 0.25

~ brevicornis (m) 118 0.70 5.27 1. 89 0.74 ( f) 139 0.90 2.63 2.13 0.55

~ lysianassa (m) 91 1.17 6.23 2.85 0.69 (f) 92 0.90 1. 79 2.39 0.43

~ hardwickii (m) 98 1. 00 6.66 2.52 0.73 ( f) 111 1. 01 2.76 2.44 0.53

25

3.1. 7 Monitoring and analysis of landings of carpet clams (Paphia undulata) at sungai Batu, Kedah.

The landings of carpet clams at Sungai Batu, Kedah were

monitored monthly during the year. The catch of carpet clams by

the vessels based at Sungai Batu averaged about 1. 96

tonnes/boat/day. The boats continued to dredge for the clams in

waters within Zone B between Pulau Payar and Pulau Langkawi.

Length frequency data of the carpet clams were also

collected from the catch of the boats monthly, and preliminary

analysis of the data provided estimates of Loo and K values for

the clams landed at Sungai Batu. The values of Loo and K

obtained were 57mm (shell length) and 1.36 per year respectively.

3.1. 8 Prawn resource survey in the coastal waters of the west coast of Peninsular Malaysia.

The survey was carried out with the research vessel K.K.

"PELALING" from 31/7/90 to 31/12/90. Although the survey was

planned to cover the coastal waters of the whole west coast of

Peninsular Malaysia, only the waters of Kedah/perlis and a part

of Perak were surveyed before the survey had to be terminated due

to shortage of crew members and breakdown of the research vessel

at the end of December. A total of 68 successful trawl stations

were completed during the survey.

Results from the analysis of the survey data indicate that

the highest average catch rate of penaeid prawns was obtained in

Perak waters where a catch of 1.55 kg/hr of prawns was recorded.

26

The catch of penaeid prawns from the waters of Penang was also

comparable to that of Perak where an average catch rate of 1.48

kg/hr was obtained. The catch of penaeid prawns in the waters of

Kedah/Perlis was very poor. Only 0.31 kg/hr of prawns were caught

on the average from the Kedah/Perlis waters during the survey.

However, the squids appear to form a very large component of the

total catch from the Kedah/Perlis waters (17%) compared to 7% and

6% from the waters of Penang and Perak respectively.

Three species appeared to be dominant in the waters of

Kedah/Perlis, Penang and Perak. These were Penaeus merguiensis,

Metapenaeus lysianassa and Parapeneopsis hardwickii. In

addition, Metapenaeus affinis was also a dominant species in

Perak waters. The survey results also indicated that all species

of the genus Parapeneopsis and 3 species of Metapenaeus (~

brevicornis, ~ dobsoni and ~ lysianassa) are shallow water

species, mostly found in waters

Estuarine waters of sungai Sangga Besar, Kuala Sepetang

The tagging trial was carried out on 13/11/90. Prawn

specimens for tagging were obtained with a push net (pukat

surung) using a boat powered by an inboard engine. A total of

243 prawns were tagged and released in the estuarine waters. Of

these, 135 specimens were Metapenaeus brevicornis, 34 were

Penaeus merguiensis, 33

Parapeneopsis sculptilis,

Penaeus semisulcatus.

were

and

Metapenaeus

1 each of

affinis, 39 were

Penaeus monodon and

Up to the end of December, the recovery of tagged prawn

specimens ranged from 3% to 20% for the various species tagged.

However, about 85% of the tagged prawns were recovered between 1

to 7 days after release. While the short period between release

and recapture does not allow for the study of their growths, the

data nevertheless indicate some limited migration of the prawns

along the coast towards the north as well as southwards, during

the period.

Coastal waters of Zone A&B off Kuala Kurau, Perak

A total of 51 specimens of Metapenaeus affinis were

collected with a trawl net towed for short durations, and

subsequently tagged. The trial was carried out during the last

week of November, and the tagged prawns were released at 2

locations viz. (a) Lat. 04° 58.5', Long. 1000 20.6'and (b) Lat.

05 0 12.0 1 , Long. 1000 14.6'. However, there has been no recovery

28

of the tagged prawns to date. This may be due to the small

number of tagged prawns released.

3.1.10 studies on the recruitment of the penaeid prawn Penaeus merguiensis in the estuarine waters of Kuala sepetang, Perak.

Trials with 3 types of fishing gears were carried out during

the year to sample the estuarine waters and tributaries at Kuala

Sepetang for postlarvae, juveniles and sub-adults of Penaeus

merguiensis to determine changes in their abundance, if any, as

well as their catchability with the different types of fishing

gears. The fishing gears used were push net operated with a

mechanized boat (pukat surung), beam trawl, and set bag net.

Prel'iminary analysis of the data obtained indicated that

juvenile Penaeus merguiensis dominated the catches of the push

net during the day, and almost completely absent from the catches

during the night. The juveniles of Metapenaeus brevicornis

dominated the catches during the night. However, the beam trawl

used appeared to be rather inefficient and its design is

currently being reviewed and modified to improve its performance.

The data also do not indicate any significant peaks in the

monthly abundance of the juveniles and sub-adults so far.

Further monitoring of the abundance of the various life history

stages in the study area is required with an optimum samplinq

gear.

29

3.1.11 Monitoring and analysis of landings composition of commercial trawl boats.

(i) Fish Trawlers.

(a) Zone B Boats.

and catch

Zone B fish trawlers were monitored at 2 major fish landing

centres namely Pulau Pangkor, Perak and Batu Maung, Penang. The

boats monitored usually only made daily fishing trips. The

monthly average catch per trip recorded for the boats from Pulau

Pangkor was observed to be generally higher than those of Batu

Maung. The monthly average catch per trip per boat at Pulau

Pangkor ranged from 247 kg to 1565 kg, while those based at Batu

Maung obtained between 342 kg and 1236 kg per trip per boat. It

was also observed that the average catch of trash fish by the

Pulau Pangkor boats was higher than those boats based at Batu

Maung. Trash fish contributed to about 53% of the total catch of

the trawlers from Pulau Pangkor compared to around 47% observed

for those boats at Batu Maung. However, the commercial fish

catch obtained by the trawlers at Pulau Pangkor was also higher

than those obtained by the boats based at Batu Maung.

Pelagic fish formed the bulk of the catches of the trawlers

from both Pulau Pangkor and Batu Maung. Rastrelliger brachysoma

was the dominant pelagic species landed by the Pulau Pangkor and

Batu Maung boats. In addition, sUbstantial quantities of Pampus

argenteus and Formio niger were also landed by the boats from

Batu Maung. Squids and cuttlefish also constitute an important

component of the total catch of these trawlers from both areas.

30

The dominant demersal fish species caught by the trawlers

from both landing centres were Nemipterus japonicus, Johnius

aneus and Johnius sina.

Juveniles of commercial fish species formed the bulk of

trash fish catch of the trawlers from both areas.

the

They

contributed to about 82% and 76% of the trash fish catch obtained

by the trawlers from Pulau Pangkor and Batu Maung respectively.

The dominant species encountered were Stolephorus SDQ, Sardinella

fimbriata and Selar kalla. The true trash fish species commonly

found were Leiognathus bindus, Leiognathus

lagocephalids.

Zone C Boats

elongatus and

The catches of Zone C trawlers were monitored only at Hutan

Melintang, Perak. Two categories of Zone C trawlers were

monitored namely Zone C1 trawlers (40 - 69.9 GRT) and Zone C2

trawlers (>70 GRT) between June and December. The monthly

average rates of Zone C1 trawlers were generally lower than those

obtained by the Zone C2 trawlers. The monthly average catch rate

obtained by the former category ranged from 8886 kg/trip/boat to

11163 kg/trip/boat, while the latter category averaged between

6319 kg/trip/boat and 16143 kg/trip/boat. The difference is

attributed to the difference in the number of fishing days per

trip. The Zone C1 boats averaged 6-7 days per trip, while the

Zone C2 trawlers usually averaged 8-10 days per trip. Commercial

fish contributed to about 47%-51% of the total catch of these

trawlers.

31

Demersal fish contributed to the bulk (70%-73%) of the total

commercial fish catch of both categories of trawlers. The

dominant species caught were Priacanthus macrocanthus and

Nemipterus delagoae. The dominant pelagic fish species landed by

these trawlers included Rastrelliger §Qp and Scomberomorus §Qp.

However, pelagic fish only accounted for about 13%-18% of the

total catch of the Zone C trawlers.

About 82%-86% of the trash fish catch is made of juveniles

of commercial fish species. These were predominantly juveniles

of Selaroides leptolepis, Saurida undosguamis and Decapterus

maruadsi.

(ii) Prawn Trawlers

The prawn trawlers based at Batu Maung, Penang were

monitored. These boats usually fish at night, bringing back

their catch the next morning. The monthly average catch rate of

these prawn trawlers ranged from 74 kg/trip/boat to about 168

kg/trip/boat. The commercial component of the catch was between

36% to 77%. Prawns contributed between 13% to 35% to the

commercial component of the catch, with monthly average catch

rates ranging from 12 kg/trip/boat to 46 kg/trip/boat.

The main fish species caught were Nemipterus japonicus,

Johnius aneus, Johnius sina and Upeneus sulphureus, while the

dominant prawn species were Metapenaeus ensis, Penaeus

semisulcatus and Metapeneopsis ~.

32

3.1.12 Biological study on Sepia aculeata landed at Kuala Kedah, Kedah.

Length frequency data on Sepia aculeata collected from the

landing centre at Kuala Kedah between November, 1989 and June,

1990 were analyzed with ELEFAN to obtain some estimates of its

fishing mortality and exploitation rate. The K(per year) value

obtained was 1.6, while the fishing mortality was 0.239. The

exploitation rate (E) computed was low, at only 0.096. However,

these were preliminary analyses using only 8 months of data.

Data over a longer time frame are required to provide a more

confident analysis.

3.1.13 Monitoring and analysis of landings and catch composition of Sepioteuthis lessoniana portable traps.

The monitoring of the catch of 6 fishing units which had

been issued permits to operate portable traps to fish for

Sepioteuthis lessoniana was started in the middle of October

with the onset of the season for the fishing of the above

species. Two monitoring trips were carried out till the end of

December. It was observed that almost the whole catch consisted

of Sepioteuthis lessoniana of marketable size. Other species

caught were cuttlefish and some demersal fish which contributed

to less than 1% of the total catch. The average catch obtained

by these fishing units was around 3-6 individuals per trap per

immersion. However, the duration of trap immersion was highly

variable, ranging from 5 hours to 23 hours. Generally, the

catches of Sepioteuthis lessonania obtained by these traps

33

consisted more females than males (by numbers) . However, the

average size of the males caught was much bigger than that of the

females. Eggs of squids were also observed to be attached to the

traps when they were hauled up after each immersion ( indicating

that the individuals caught were probably attracted to the traps

to lay their eggs (with the traps serving as substrate for

attaching their eggs). The study will be continued in 1991 to

obtain more data for further analyses.

3.1.14 Experimental trials with pair trawl net.

The experimental trials with pair trawls net using

K. K. "JENAHAK" and K. L. "BAWAL" 'Here continued during the year to

determine the rigging and operational procedures for optimizing

the gear's fishing efficiency. The rigging design and fishing

gear operation were successfully completed during the trials.

Further trials will be carried out in 1991 to determine the

efficiency of the gear which has been redesigned to improve its

operation in rocky/coral areas.

3.1.15 comparative studies on the efficiency of 2-seam, 4-seam and 6-seam trawl nets.

One trial was conducted during the year with the research

vessel K. K. IIMERSUJI". However I i-t had to be aborted after all

the experimental nets were damaged during the early part of the

trials. Subsequent trials could not be carried due to

unavailability of the vessel as well as the priority given to the

conduct of experimental trials with pair trawl nets.

34

3.1.16 compara'tive study on the c1esign and efficiency of crab traps.

A study was conducted in the coastal waters off Pulau

Langkawi to compare the performance and efficiency of 5 designs

of crabs traps, namely:

a) Square with trap entrance at the side. b) Oval with trap entrance at the side. c) Oval with trap entrance at the top. d) Oval with trap entrance at the top and side. e) Local fishermen design (oval with the entrance at the

side) .

A set of 42-45 traps of each design were used in the study.

The results indicate that the traps with an entrance at the side

had better catch rates than those with an entrance at the top,

while the oval-shaped traps caught more Portunus pelagicus than

the square-shaped traps. It was also observed that the

Institute's oval-shaped trap with an entrance at the side (design

b) was more efficient than the local fishermen's traps (design

e) •

3.1.17 Monitoring and analysis of fishing trials conducted jointly with the Extension and Education Division of the Department of Fisheries, Malaysia.

Four types of fishing gears were introduced to the fishermen

by the Extension and Education Division of the Department of

Fisheries{ Malaysia for demonstration trials. These gears were

vertical longline, pouched driftnet, lobster trap and red snapper

bottom gillnet.

35

Vertical Longline.

The catch rate obtained by the vertical longlines was lower

than those of baited bottom longlines currently employed by the

local fishermen (8.5 gm/hr. immersion against 19 gm/hr. immersion

respectively) . The size of the fish caught by the vertical

longlines was also smaller compared to those caught by the bottom

longlines. This is probably due to the size of the "MATSUBARI"

hooks used in the vertical longlines.

Pouched Driftnet

that of a

that the

The efficiency of this gear was compared with

single layer prawn driftnet. The results indicate

average catch rate of the pouched driftnet was very low

to that of the single layered prawn driftnet. The

compared

catch of

prawns obtained by the former was only 33.6 gm/net panel compared

to 123.6 gm/net panel obtained by the latter. This net is

therefore unsuitable for introduction to the local fishermen.

Lobster Traps

Traps of 2 types of design were demonstrated to the

fishermen namely oval-shaped and cone-shaped traps. The trials

did not produce any sUbstantive results as no lobsters were

caught during the trials. Further trials would be required.

Red Snapper Bottom Gillne~

The fishing gear did not catch any red snappers during the

demonstration trials although they were caught by traps operating

in the same area. However, a number of other demersal fish were

caught by the gear. Further trials would be carried out in 1991.

36

(b) Aquaculture Research

3.1.18 Larviculture and nursing of fry of Lates calcarifer and EDinephelus suillus.

Larvicul ture and nursing of ·the giant sea perch / seabass

(Lates calcarifer) and E~inephelus suillus fries were carried out

using one-day old hatchlings received from the Department's

marine finfish hatchery in Tanjung Demong, Terengganu.

(a) Lates calcarifer

A total of 3 consignments of 1-2-day old hatchlings were

received from Tg. Demong. The first consignment of 450,000 2-day

old fry encountered more than 50% mortality during

transportation. The second consignment of 600,000 2-day old

hatchlings was received on 20.3.90 and the third consignment of

500,000 I-day old hatchlings on 6.7.90.

Fry survival was improved with the use of the newly-

installed ultra-violet sterilizer which was able to

reduce the bacteria plate-count in the seawater to a very low

level. A total of 132,000 fry were produced between January-

August 1?J90.

(b) Epinephelus suillus

About 1,700 fry (4 cm total length) of Epinephelus suillus

were received from PPEIL, Tg. Demong. The fry were nursed in

37

rectangular fibreglass tanks on a diet of minced fish until a

size of 8 cm attaining a survival of 63% (1071 fry remaining).

They were then transported to cages for culture.

3.1.19 Brocdstock maturation and spawning of Eoin.§U2heluJi §J2.

A group of female fish of Epinephelus suillu~ (3 kg body

weight) were treated with BCG (Human Chorionic

Gonadotropin) hormone at a dosage of 500 I.U/kg fish to

inducf~ the development of their ovaries. Heanwhile a

group or female fish (also abou't 3Jcg. body weight) was .fed'

~vith methyltestosterone (at 3% body weight) mixed into

their diet of minced fish to induce sex reversal. The

feeding of methyltestosterone was carried out for over 2

months but the rate of sex reversal was very low. Only 2

out of 25 female fish changed to male. No induced

spawning was achieved so far.

3.1.20 culture of live food organisms

Pure cultures of various algal species, including Chlorella

virginic£h Tetraselmis _Chaetoceros calcitrans and

Isochrysis galbana were maintained and routinely produced for the

production of rotifers and as food organisms for the larval

stages of mollusc and sea bass. Rotifers were used as food

organisms for the larval s'tages of the seabass.

")0 .JU

3.1.21 Cockle transplantation and culture

Cockle reseeding programmes in 1990 were carried out in the

states of Johor, Perak, Penang and Kedah. The sites chosen

for the implementation of the reseeding programme ';"ere Sungai

Suluh and Sungai Suluh Kecil, Johor; Lekir and Bagan Tiang,

Perak;

Nyior,

Sungei Semilang and Pulau Aman, Penang; and

Kedah. Studies on the growth, mortality and

Selat Bagan

maturity of

cockles were carried out in these areas. Cockles that were seeded

in 1988/1989 in some of these areas were also monitored.

(i) Coc];:l,s reseeding progrmn.me 2990

The cockles reseeded at Sg. Suluh, Johor encountered 35%

mortality a month after reseeding beca~se ~f predation from the

gastropod Thais ,§Q and s~arfish. The cockles reseeded at Sg.

Suluh Kecil on the other hand are still growing well with minimum

mortality up till end of 1990.

very

boats

The cockles reseeded

high mortality because

into the culture

at

terminated

started.

3 months after

Lekir, Perak

of infringement

area. The

encountered

by trawler

culture was

the reseeding programme

Cockles reseeded at Sg. Semilang, Penang have mixed

results. The cockles reseeded

while those at unit B well

from predation by Thais ~

at Unit A were

encountered high

Cockles reseeded

growing

mortality

at Pulau

Aman also encountered about 20% mortality due to predation

39

from starfish.

HOvJever f cockles sO'vln at Selat Bagan Nyior, Kedah are in

good condition and mortality is about 5%.

(i) Cockles reseeded in 1988/1989

Cockle sown in Kedah on 17.9.88 ,;,t.tained

harvestable size in January 1990. The cockles seeded in Bagan

Tiang, Perak in 1988/89 were monitored up to March 1990 by which

time the cockles had reached a mean si?:e of more than 32mm. 'l'he

cockles "cook more than 1 year to reach the legal

minimum size of 31.8mm from an initial size of 14mm.

and the size at first ~aturity was 18mm. A total of

3796 bags of marketable cockles (worth $60,000) were

produced after 3 months of harvesting. This project

made a nett profit of about $17,000.

3.1.22 Mussel transplantation and cultUre

(i) Mussel transpla.ntation prognmrme

Due to a shortage of mussel seed supply from the Selat

Tebrau region in Johor for the year 1990, the mussel

transplan'tation programme was carried out only in Pulau singa and

Batu Lintang, Kedah; Kg. Penor, Pahang: and Teluk Gong, Selangor.

A total of 2120 strings of mussel spats were

transplanted to the above-mentioned areas. The mussel sp.ats

transplanted to Pulau Singa, Kedah in February, 1990 had reached

40

harvestable size in August, 1990, while those in Kg. Penor,

Pahang suffered 80% mortality because of drastic reduction in

salinity of the water (to 0 ppt) in the culture site due to

floods.

The monitoring of the mussels transplanted during 1939 was

continued. A total of 4100 strings of mussels costing $74,790

(including rafts, stakes, mussel spat and transportation) were

transplanted in Perak in 1989. From these, a total of 26.188

tonnes with a value of $18,398 have been harvested in Kg. Jarum,

Kg. Baru, Telaga Nenas and T. Senangin. However, the collection

of data on the harvest and si~le of mussels from the

transplantation carried out in Kedah in 1989 were still not

completed.

Generally the mussel transplan-tation progri:..11TUUe has been a

success and has brought greater awareness to the culturists that

mussel farming could be lucrative. Some of the problems

encountered in the programme included inadequate seed supply,

poor quality seed and poor market.

problem.

(ii) Seed collection

Poaching was also a serious

Seed collection trials ,vere c2,rried out in Sg. Muar f Sg.

Rekoh and Masai, Johor and Teluk Mas and Sebatu, Melaka.

Encouraging results were obtained from all 1-::hese areas,

especially from Sg. Muar where an average of 20kg string of spat

(0.5-3.0mm) were obtained between the peak season of March to

41

Hay 1990.

{iii} Sal

A study on the salinity tolerance of mussel was conducted in

t.he labo:ci3.Lory. The salinity range selected for the tolerance

study ranged from 10-35 ppt. The salinity tolerance of

the animal was measured by the rate of filtration of the

red cl:y(; I neu·tral red. I~1 unfavcmr2,ble concH 1.::ion8 .

filtration rate would b o slow. It "\:ias found t .. hat the

optimal salinity was 30ppt and conditions below

20ppt were not suitable.

antation and culture

The oysJcer transplant.ation and culture project is

d~vjded into two components:-

(i) BOBP oyster culture programme;

(ii) Oyster culture programme conducted by IPP.

This programme is carried out with the ·technical and

financial support from the Bay of Bengal Fisheries Development

Programme. studies are mainly concentrated on spat collection

and grow-out in Kg. KeJ.ibang, Pulau Langkawi; Batu I,in'tang I

Kedah; Telaga Nenas and Kg. Teluk, Perak; and Sg. ]'I[erch;::mg and

Kuala setiu in Terengganu.

42

Kg. lZelibang in Pulau Lanqka~"i 1das found sui table for the

while

Kedah; Telaga Menas and Kg. Perak ,"vere

suit2.ble fCJr the collection and ClTO\v-out of -, Sg.

(:·.nJ 1\. SC'.::t:iu r had been found to be suitable

for the cultu~e of Mark2table oysters have been

shucked;

usually sold shucked.

a.II technique using i:he

abundance of oyster eyed-larvae ~s an index still needed

irnprov There was evidence to suggest spatfall

was related to the tidal cycle and salinity fluctuation.

Netlon used as cultch ma~er had been found to be suitable

lD the spat collection s However, netlon is an ive

material and a lot of t is required to separate the spat from

Collectors such as discarded motorcycle tyres

table in Sq. Merchang.

TCf:;ts were c,J;,;o carrl.ecl O1Xt on t.hE' faecal coliform count in

the oysters. Results showed that chilled oysters had an average

connt: of 10 Fe HFi:i/

Spat collection carried out in Pulau Singa and trials done

since last March had not given encouraging results. Attempts to

transplant spat collected from Kg. Kelibang had also failed

because of fouling from Pinctada sp .. pteria sp and Balanus sp ..

Two rafts were built for spat collection and grow-out of ~

iredalei in Kelantan. Oyster shells used for

collecting spat were also distributed at the sea bottom.

Merchang and Kuala setiu in Terengganu were found to be

suitable areas for spat collection and grow-out.

Oyster culture in these 2 areas is now being carried out by

farmers.

3.1.24 Fish health and disease

(i) Ulcerative Syndrome in Padi Field Fishes

The water quality in the padi fields and irrigation canals

appeared within the normal range-except that the NH3-N levels

ware high, ranging from 0.4-3 mg/l. Levels of heavy metals in

water and fish tissues were generally low and no correlation with

disease occurrence could be established. Aeromonas hydrophila and

Ewardsiella tarda were isolated from diseased Clarias sp both

from lesions and kidney. ~ hydrophila was consistently found in

ulcerated Trichogaster pectoralis. Fungi belonging to the

Saprolegniaceae family were frequently found in the padi

field fishes. Bacteria plate-count in the irrigation canals

ranged from lXl0 5 bacteria/ml to 5XI0 5 bacteria/mI. and in the

padi fields ranged from lXl0 5 bacteria/ml to 5XI0 6 bacteria/mI.

44

No serious epidemic of epizootic ulcerative syndrome was

reported in Malaysia in 1990, except for some isolated cases

which could be linked to urea application and prolonged drought

condition.

(ii) Virulence of Vibrio on seabass fry

This study showed that healthy seabass fry were not infected

with Vibriosis when placed in seawater containing

bacteria/mI., 4-6XI0 6 bacteria/ml and 4-6XI0 7 bacteria/mI., for

24 hours. Healthy seabass fry injected with Vibrio in phosphate

buffered saline containing 4-6XI0 3 bacteria/fish,

bacteria/fish and 4-6XI0 6 bacteria/fish were also free from

symptoms of Vibriosis.

(iii) Water quality and fish health monitoring in cage culture system.

Average bacteria plate-count (from July to october 1990)

sampled from the waters of the cage culture site in Batu Uban

showed that the bacteria plate-count from waters in the cages

appeared higher than the counts outside the cage. Bacteria

isolated from the water included Aeromonas, Vibrio

parahaemolyticus, alginolyticus, Edwardsiella sp and

Pseudomonas sp. Vibrio is the most common pathogen isolated

from the tissues (kidney, liver and lesion) of diseased fish.

There appeared to be no difference between the NH3-N,

Dissolved Oxygen and pH values of the water within and outside

the cages. The values recorded for NH3-N, Dissolved Oxygen and

45

pH ranged from O.5-0.7ppm, 5.5-8.9ppm and 8.1-8.5 respectively.

(iv) Fish mortality/disease occurrence

Cases of fish/prawn mortality due to disease were

investigated in Batu Uban, Bukit Tambun, Sungei Udang, Nibong

Tebal in Penang, sungei Petani in Kedah and Daerah Manjung and

Kuala Trang in Perak. Most cases referred to were from farmers

carrying out cage culture of fish, although pond culture of fish

(ikan keli in Sungei Udang) and penaeid prawn pond culture

(Manjung) w~re also investigated.

The most common pathogen isolated from the diseased fish was

Vibrio although Aeromonas and Pseudomonas sp, were also

isolated. Fungal and protozoan infection (white spot due to

Cryptocaryon irritans) were also found. In almost all cases,

practices

Insufficient

disease in the culture was caused by bad culture

overstocking and wrong feeding practices.

feed and feeding with low quality rotting fish could have also

caused nutritional deficiency and diseases.

(v) Issuance of health certificate

Health certificates issued for the export of life fish and

aquatic plants indicated that the most common aquarium fish

exported through Penang was the discus. A total of 12.219

pieces were exported, with the bulk (86%) going to Japan, and 8%

to Australia. A total of 7792 pieces of Carassius auratus were

exported through Penang. all of it going to Australia. A total

of 51.9 tonnes of Scylla serrata were exported through

Penang.

46

3.1.25 Seaweed Culture

Experiments were concentrated on the species Polycavernosa

cylindrica found in the Middle Bank, Penang.

(i) spore-setting

spore-setting was tried out with rafia collectors and found

to be successful. Other collectors like oyster shells and

polyethylene strings will be tried out in future.

(ii) Grow-out in the sea

Spore on rafia strings were transferred to the sea for grow-

out. However, a lot of strings were broken out at sea. Other

stronger strings such as polyethylene will be tried out in

future.

(iii) Grow-out in ponds

Grow-out in the

encouraging.

disintegrated

Seaweed

due to

ponds

growing

the

did

on

not

the

acid-sulphate

appear very

pond-bottom

condition.

However those grown

pond-bottom achieved

on plastic nets suspended above the

a final weight of 4kg from an

initial weight of lkg. Growth rate was between 2.5-4% a

day. There is a possibility that there are 2 varieties

of Polycavernosa growing in the ponds, one with a faster

growth rate than the other.

(vi) Extraction of Agar

Hydrogen peroxide was used as a bleaching agent in the

processing of Polycavernosa. The quality of the agar obtained

from the process where hydrogen peroxide was used was the same

47

as those obtained from the process where hydrogen peroxide was

not used.

3.1.26 Technical support for coastal finfish operations in Tanjung Demong, Terengganu

(i) Larviculture of Epinephelus suillus

hatchery

The PPBIL, Tg. Demong has succeeded in the spawning of the

grouper, Epinephelus suillus since May 1989, and in larval

culture of the grouper on an experimental scale in early 1990.

Larvae of Epinephelus suillus were obtained from natural

spawning and 1-3 day-old larvae were fed eggs or trochophore

larvae of oysters. Rotifer SS were given to the larvae that were

2-6 days old and rotifer S given to larvae between 6-22 days

old. Larvae from 22-40 days old were given Artemia that had been

enriched with chicken egg and fish oil. Larvae 40 days old and

above were given minced fish. In 1990 about 9000 fish fry were

produced.

(ii) Larviculture of Lutianus ~

Larviculture of Lutianus ~ was carried out for the first

time in September 1990 through induced spawning from a single

female. The female was given 2 injections of ReG hormone

containing 500 IUjkg. body weight. The larvae were given their

first feed of oyster and trochophore larvae when they

were 4-5 days old. This feed was followed by rotifers,

Artemia and minced fish. A total of 338 fry of more than

39 days were produced.

48

(c) Ecology Research

3.1.27 Management of the Artificial Reef Development

The management of the artificial reef

Research and

research and

development accelerated and expanded in 1990 under the Fisheries

Resource Enhancement component of the Asian Development Bank

Malaysia Fisheries Research and Development Project (ADB-MAL

Fisheries R&D Project) . Initially, site surveys were carried

out and baseline studies employing direct visual observations and

fishing were conducted to quantify fish abundance prior to reef

development. The effectiveness of new materials such as PVC

pipes and specially designed concrete blocks were then introduced

as experimental reef materials at Pulau Lembu, off Pulau

Langkawi. Three (3) types of reef modules were constructed at

the 3 sites: PVC reefs, PVC-concrete reefs and concrete reefs.

The distance between each site was estimated to be 60 feet. The

reefs were monitored regularly to assess fish populations, rate

of encrustation and structural integrity.

Due to the shortage of available manpower in the Ecology

Unit, the staff had to concentrate on the artificial reef

research of the ADB-MAL Fisheries R&D Project. As a result

close monitoring of the tyre and concrete reefs carried under the

comprehensive programme of the Fifth Malaysia Plan could not be

carried out. Also the critical shortage of crew members on the

research vessel K.K. JENAHAK has seriously affected the smooth

49

implementation of this and several other sea-based research

projects.

3.1.28 study on the coral reef ecosystem - Marine Parks

studies carried out will help to provide baseline

information for the development of a management plan, increase

understanding of the Marine Park concept and facilitate the

resolutions of certain management issues. 2 major areas were

surveyed in 1990: Teluk Nipah, Pulau Pangkor and Pulau Papan,

Labuan.

At Teluk Nipah, Pulau Pangkor, transect studies indicated

the presence of hard corals such as Acropora and Porites species

and soft corals especially Sinularia species. Sea urchins and

sea cucumbers were abundant near the shore. Among the fishes

observed were Ikan Kerapu and Ikan Jenahak. Early observation

indicated that a large portion of the coral reef was destroyed

and/or naturally died. Corals were exploited and sold as

ornamental objects in Pulau Pangkor and Lumut. On the whole,

this area has still a good coverage of corals and steps should be

taken to protect the area.

Pulau Papan,

Tanjung Kiamsam,

Labuan, and the neighbouring areas such as

Pulau Kuraman, Pulau Rusukan Besar, Pulau

Rusukan Kecil and Kg. Layang-Layang were surveyed by a team

consisting of IPP, Fisheries Headquarters and Tentera Laut Diraja

Malaysia (TLDM) personnel. studies indicated a poor coral

50

coverage in Pulau Papan.

indiscriminate activities.

Corals were probably destroyed due to

Instead the area is now covered with

seaweeds such as Sargassum, Padina, Turbinaria, Dictyota and

other species. Pulau Kuraman, Pulau Rusukan Kecil and Pulau

Rusukan Besar have better coral coverage and it is recommended

that they be protected or established as marine parks. The

shortage of manpower had also affected the smooth and effective

implementation of this programme.

3.1.29 study on the Seagrass Ecosystem

A brief survey was carried out in the coastal waters of

Johore: Pulau Babi group of islands, Pulau Sibu and Pulau

Tinggi to study the distribution and identify the seagrass

species. The species observed in Pulau Babi Besar were Halophila,

Halodule, Cymodocea and Syringodium; in pulau Babi Tengah they

were Halophila and Cymodoceai in Pulau Tinggi, Halodule and

Cymodocea species; and in Pulau Sibu, Enhalus acoroides.

3.1.30 Cockle Depuration studies

Cockle depuration studies were carried out but stopped

because of the breakdown in the stomacher. Samples were then

sent to the Veterinary Department to be analysed. Observations

indicated that the level of the faecal coliform could be reduced

through the depuration process. The presence of other bacteria

was also identified i.e. Bacillus sp. and Flavobacteria sp.

However, the level present was considered to b~ normal.

51

Two experts from FAO (Rome) came to observe the studies

carried out by FRI and later made recommendations to improve the

methodology used and to establish a commercial plant for cockle

depuration.

3.1. 31 Monitoring of Heavy Metals in fish, shellfish and sediments

Analytical work was carried out on sediments and some

marine and freshwater fishes. There was a marked progress on

sediment analyses, particularly in the digestion technique. A

preliminary examination was carried out to test for metals in

water and the results obtained were satisfactory to warrant the

purchase of an in-situ sampler. The Pollution Unit was also

involved in a joint programme with the Nuclear Energy Unit of

PUSPATI titled 'Marine Sediment Contamination Survey'.

Analyses on cockles collected from Juru, Sg. Perai and K.

Sepetang indicated that the Juru cockles were much more

contaminated than those from Sg Perai and K.Sepetang. Results

also indicated that the value for cadmium in the K. Sepetang

cockles has exceeded the maximum permissible limit of 1 ppm.

Close monitoring of fish and shellfish from these areas is

required to study the nature of the problems and the necessary

steps to be taken for safe human consumption.

Analyses of metal content in muscle tissues of marine fishes

indicated safe levels but those in the liver tissues had elevated

values but since normal consumption is scarce and quantity small,

52

there should be no cause for alarm. The freshwater fishes

sampled showed low metal content and hence are fit for

consumption. Sediments collected were also analysed to determine

pollution levels and sources.

3.1.32 Analyses of pesticides in shellfish and freshwater fish

The Gas Chromatograph was not functioning very well for a

couple of months in early 1990. Analytical work resumed after

July and samples of freshwater fishes and shellfish were then

analysed. Among the freshwater fishes analysed were siakap

(Lates calcarifer), patin (Pangasius sp.), sebarau, keli (Clarias

batrachus), sepat siam (Trichogaster pectoralis) and sepat

ronggeng (~ tricopterus); and the shellfish analysed were

mussels, oysters and cockles.

On the whole, with reference to Swedish standards, results

indicated that values for total lindane (HCH) for Sepat Ronggeng

and mussels have exceeded the 200 ug/kg limit. Analyses of some

fish samples namely Ikan Sebarau (Hampala macrolepidota) also

indicated high levels of total lindane and endosulfan.

3.1.33 studies on fish kills in inland and coastal water and water quality Monitoring

Studies on water quality with reference to tidal

fluctuations was carried out in Kuala Gula and Kuala Sepetang to

determine the cause of periodic fish mortality at cage culture

53

sites. Investigations were also carried out at the Kuala Kurau

cage culture site.

The monitoring of water quality at Kuala Gula indicated tha"t

it is not adversely affected by low tides, thus fish kills could

be due to pollution or lowered salinity after a heavy downpour.

For Kuala Sepetang river, the conditions were different in that

the dissolved oxygen values started to fall with increase in

suspended solids and this condition was evident especially during

low tides. It is recommended that close monitoring of the water

quality with tidal fluctuations be carried out before cage

cultures are set up.

The monitoring of " water quality around Pulau Pinang namely

Teluk Bahang, Gelugor Jetty and Batu Maung was re-established.

Classical parameters such as dissolved oxygen, BOD, temperature,

salinity, suspended solids and ammonia were determined in 1990.

It is hoped that the analyses for heavy metals and bacteria

content could be carried out in 1991. currently, based on the

above parameters the water quality around Batu Maung is

considered clean but the quality in the years to come could not

be ensured, especially in view of the new development projects

in that area. The establishment of the new FRI complex would

have to take into consideration the quality of water and a

suitable site where water is to be pumped for research purposes.

54

3.2 Nation .. \l Prawn Fry Production & Research Centre, Kedah

3.2.1 culture of live food organisms

The culture of various species of phytoplankton in weather-

controlled rooms is well established. To maintain purity of the

culture and to reduce contamination, stringent water treatment

is essential. However, such facilities are relatively expensive

and production is limited by the physical dimension of the air-

conditioned room.

For the new hatchery, the production of algae (mostly

Chaetocero~ sp),

inoculum for 300

outside the room.

from the small algal room is instead used as

liter tanks under transparent roof sheets

A cell density of 1.0 - 1.4 million cells/ml

could be achieved after 3 days of culture under favorable weather

conditions. The production is used as seed stocks for 15 ton

concrete tanks. Production from the 15 ton concrete tanks, at a

density of 0.87 - 1.14 cells/ml after another 3 days of culture,

is used for larviculture.

The major problem of such scaling up outside the algal room,

where the air is not subject to filtration as in the case of air-

conditioned room! is serious contamination by ciliates.

Filtration of water down to 1.0 micron does not appear to

completely remove the ciliate, which may enter through

atmospheric transport. The problem is particularly serious if

the algal culture period needs to be lengthened as a result of

55

unfavorable weather conditions. Besides grazing by ciliate which

leads to lower cell counts or complete failure of the culture,

the contaminated culture if introduced to the larviculture tanks,

would also interfere with the well being of the larvae.

As quality of the algae from 300 liter tanks is consistently

better than that from the 15 ton concrete tanks, which are not

closed, it has been suggested that the scaling up of culture

operation should stop at 300 liters. Extra 300 liter tanks have

been ordered and the procedure would be tried out soon.

As a service to the marine shrimp hatchery industry, stocks

of relatively pure algae are also routinely distributed free of

charge to hatchery operators.

From the second half of the year onwards, the Centre also

maintains culture of rotifer, the initial stock of which was

obtained from Tanjung Demong. The culture again necessitates the

culture of chlorella. Attempts to replace the chlorella with

baker's yeast have not been successful, with the rotifer culture

collapsing after a few days. The rotifer have proved to be good

partial replacement Artemia as mysis feed for marine shrimp. The

rotifer are however primarily used for the larviculture of crabs,

a new area of research for the Centre.

3.2.2 Maturation studies of penaeus mono don

Slightly over 1400 wild female and 1000 male tiger shrimp

56

spawners were acquired for spawning purpose. However from time

a small number of gravid females were also bought to

meet immediate demands for nauplii, especially just after a major

breakcycle or for the needs of a training programme.

.About 1 '70 ':l fl' d 11 d grav.lc ..:ema es vlere acqulre . A spawne, giving

an average of 716,000 eggs and 420,000 nauplii per spawning. T~e

wild nan-gravid females were subjected to unilateral eyestalk

ablation. Out of 1,243 shrimps subjected to the treatment, 709

females (57%) responded with 1,382 spawnings. The number of eggs

and nauplii obtained per spawner were 798,000 and 332,000

respectively, giving a hatching rate of 42 %. This is slightly

lower than the 62 % obtained for gravid females. 'Though the

hatching rate is lower for the induced spawning, the slight

disc21dvantage is more t.han offset by ·the greater abundance of the

non gravid females and their ready availabili-ty.

For pond grown broodstock, raised from Ban Merbuk, only 30 %

of the 282 females treated spawned, giving a total of 153

spawnings (averaging 2 spawnings per spawner). The number of

eggs produced per spawner at 459,000 is not particularly