THE STATUS OF MARINE FINFISH CULTURE IN SINGAPORE

Khoo Lim Teo *
Chang Foo Wah **

I. Abstract

The farm production of finfish in Singapore is derived mainly from floating netcage farming, which produces some 400 MT of finfish per year. The main cultured species are estuarine grouper, seabass and golden snapper. This paper describes the status of marine finfish culture in Singapore, including site selection criteria for floating netcage farming, rules and regulation of fish culture, harvesting and handling methods and marketing strategies of the industry. Major problems encountered by the fish farming community are in the areas of feeds, fingerlings, labour and economy of scale of operation. These problems and their possible solutions are discussed.

II. Introduction

The areas available for aquaculture in Singapore are mainly confined to the coastal waters free of navigation and not exceeding 5–7 fathoms (9–13 m) at Low Water Spring Tide along the eastern and western parts of the Straits of Johore (Fig. 1). Due to the limited space, fish farming activity has to be intensive for maximum utilization. Floating netcages cultured was identified in the early seventies by the Primary Production Department as one such method of intensive aquaculture. With the implementation of the Marine Fish Farming Scheme in 1981, floating netcage fish farming has expanded to 70 farms (1988).

III. Species of commercial importance

There are three main fish species cultured in the commercial fish farms. They are the estuarine grouper (Epinephelus tauvina), seabass (Lates calcarifer) and the golden snapper (Lutjanus johni). These fish grow well under netcage conditions and attain a market size of 600 g or more within 6–8 months from stocking size of 50–100 g.

* Marine Aquaculture Section, Primary Production Department, 300 Nicoll Drive, Singapore 1749.

** San Lay Marine Culture Co., 60T Jalan Serseri, Singapore 2469.

Figure 1. Suitable sites for floating netcages in Singapore coastal waters.

IV. Annual production

The annual finfish production by netcage farms are as below:

* Figures in parenthesis are farms primarily engaged in shellfish farming.

V. Site selection criteria

The criteria for selecting a suitable site for netcage fish farming are as follows:

1. Water current and exposure: The wave height and current speed at the sites should not exceed 2 m and 100 cm/sec (2 knots) respectively.

2. Depth: The nets of the floating raft should be kept at least 2 m off the sea bottom to facilitate water flow. As 2–3 m deep netcages are recommended, the depth at farm site should therefore exceed 5 m at Low Water Spring Tide (LWST).

3. Oxygen: Dissolved oxygen levels in the area should remain generally high and stable throughout the year at around 5–7 ppm.

4. Salinity and temperature: The salinity and temperature requirement for fish farming largely depend on the culture species. The water along the Straits of Johore has a salinity of about 29 %. with an annual range of 27–30 % and water temperature of 29–31 °C with a mean of 30 °C. These conditions are considered suitable for farming of tropical marine or estuarine fish such as grouper, seabass and snapper.

5. Fouling and pollution: Fouling is more rapid in areas of slow water i.e. with current speed of less than 25 cm/sec (1/2 knot) eg., Serangoon and Sarimbun/Lim Chu Kang where mussels are abundant. In such an area, netcages would have to be washed more often to maintain good water exchange. The fouling organisms are mainly barnacles, tunicates and algae. Their rate of occurrence and predominance vary at different locations and times of the year. Pollution of coastal waters is normally a result of sewage discharge and/or industrial effluent. Levels of bacteria, ammonia and phosphate-phosphorus from sewage, and heavy metals and toxic chemicals from industrial effluent may build up to a level lethal to fish and hence fish farming should be avoided in such affected areas. Fish kills may also arise indirectly from blooms of phytoplankton especially of dinoflagellates. However, the pollution of the waters in the Straits of Johore is not of common occurrence. Ammonia concentration ranges from 2–5 ug-at NH3-N/litre. Phosphate-phosphorus is 1–2 ug-at/litre. Faecal coliform counts and heavy metal levels (e.g. mercury, copper and lead) are within the acceptable safe limits for man. The dinoflagellates which cause paralytic shellfish poisoning have not been found in local waters.

VI. Rules and regulations

The fish culture (Control and Licencing) Rules 1981 were formulated under the powers conferred by Section 7 of the Fisheries Act of the Republic of Singapore. Annexes A and B provide the details of the Rules and Conditions of issue of fish culture farm licence respectively.

VII. Harvesting and handling methods

Harvesting of fish stocks in a floating netcage farm could be divided into the following steps:

1. assessment and identification of prospective cages for harvest
2. conditioning of fish stock before harvest
3. harvesting
4. post-harvest handlip

A. Assessment and identification of prospective cages for harvest

Assessment and identification of prospective cages for harvest are based on the following:

1. culture period i.e. time of stocking to harvest date, and
2. visual assessment of the percentage of fish attaining marketable size in the netcages.

The culture period is a good guide for harvesting projections. In this context, the harvest may vary from 6 to 8 months from stocking, depending on the stocking density and the species.
The marketable size ranges from 600 to 1,200 g body weight. Visual assessment of the percentage of the fish stocks reaching marketable size can be done during feeding and net-changing or when water visibility is good. An experienced operator can accurately estimate the size and number of the marketable stock in the netcage. Random harvest of the cages may cause unnecessary stress to fish and injure them.

B. Conditioning

Conditioning of the stock before harvest is vital in maintaining the quality of the post-harvest product. The conditioning process consists of two stages:

1. transferring the stock into a clean net, and
2. starving the stock for 24 to 36 hours.

The purpose of transferring the fish stock into a clean net before marketing is to prevent the fish from unnecessary abrasions with marine growths on the netting. This is done by changing the soiled net that holds the marketable fish with a clean one.
Starving the fish stocks for 24 to 36 hours is necessary to prevent the fish being shipped alive from regurgitating arising from stress during harvest and transportation. For fish being sold chilled or frozen, starving before harvest ensures an empty gut which prolongs the shelf-life.

C. Harvesting

Harvesting is relatively simple. For a small quantity of fish, the fish are caught directly with a deep scoop long-handled net without causing much disturbance and stress to the rest of the stock. For a total harvest of the cage, the following method is applied:

1. Reduce the depth of the net by lifting two opposite sides of the net onto the sides of the cage.
2. Drive the stock to one side of the cage by lifting up the net from an opposite side in stages. The fish stocks in a reduced area are then scooped out into suitable containers. Fish of smaller size are placed into adjacent nets for future harvests.

D. Post-harvest handling

There are two ways of post-harvest handling:

1. For fish sold alive: the fish are transferred into live fish tanks with strong aeration. The water temperature in the tank is reduced to 19–22 °C to reduce the metabolic rate of the fish and hence to maintain good water quality in the tank. The salinity of the water is also reduced to approximately 15 to 10 %. This is to minimize the use of seawater in the seafood restaurants.
2. For fish sold chilled or frozen: the harvested fish are first shocked and killed in cold water of 5 °C to 10 °C. During the above process the water in the cold bath is changed regularly to ensure that no slime and excrement adhere to the gills. This process is to enhance the appearance and freshness of the fish. Thereafter the fish are immediately removed from the cold bath once their opercular movements have stopped. Packing in ice and cleaning follow immediately.

VIII. Marketing strategies

In Singapore the farmed fish are mainly sold ‘live’ for consumption in local ‘live’ restaurants and eating houses. As the degree of affluence increases in the Singaporian society, more housewives now demand fish of premium quality for daily meals. Hence, a portion of the farmed fish are also sold ‘live’ in the Ponggol Live Fish Market or ‘chilled’ in the fish auction market in Jurong and Ponggol.
As the fish farming industry in Singapore develops and strengthens, some farmers also export their seabass in ‘live’ form using specially designed vessels to other foreign markets such as Hong Kong.

IX. Problems

The major problems that are commonly encountered by the fish farming community are in the areas of feed, fingerlings, labour and economy of scale.

A. Feeds

Almost all the fish farmers are heavily dependant on trash fish. However, the supply of trash fish is limited and unpredictable. As a result, projection and planning of production are most difficult and inaccurate.

A long term solution to this feed problem is to replace trash fish with formulated feeds. In this context, the Primary Production Department (PPD) of the Ministry of National Development of Singapore has been conducting research on the formulation of suitable feeds for local farmed species. Arrangement has been made with a local feed company to produce seabass feed on a pilot scale. If successful, the feed would be produced locally for supply for local farmers and export market. Formulation of feeds for other species of fish are being looked into.

B. Fingerlings

Most seabass fingerlings are imported from Thailand. Although there is no problem in obtaining regular supply of the fingerlings, the cost is high due to high freight charges and mortality arising after shipment. The condition of the fingerlings is also not consistent. There are already some farmers capable of producing seabass fingerlings commercially. More such hatcheries would be necessary in the future.

C. Labour

The present method of netcage farming requires workers who have to undertake manual labour. However such working conditions are not preferred by younger workers. There is now an acute shortage of labour in the fish farming industry. However, this problem can be partly resolved through mechanization of some aspects of the farming operation, namely, use of autofeeders for feeding the fish, fish chopper for cutting the trash fish into the appropriate size and net-hauler for mechanically raising the nets.

D. Economy of scale

Most of the farms are relatively small, usually 0.5 ha water surface, and produce an average of 10 tonnes per annum. Due to the problems mentioned above, expansion of the scale of operation becomes difficult and most farms do not enjoy economy of scale. The cost of production remains high. The shift of feed from trash fish to formulated feed, local production of fingerlings, and mechanization of fish farming operations would allow the farms to expand the scale of operation and achieve economy of scale.

In addition, the introduction of modern advanced technologies, such as semi-submersible deep netcages with fully mechanized equipment for daily operations, floating raceways and rotatable netcages would stimulate and accelerate the fish farming industry development as well as upgrade the technology of netcage farming in Singapore.

Annex A

THE FISHERIES ACT
(Chapter 294)

THE FISH CULTURE (CONTROL AND LICENSING) RULES, 1981

In exercise of the powers conferred to section 7 of the Fisheries Act the Minister of National Development hereby makes the following Rules:

1. These Rules may be cited as the Fish Culture (Control and Licencing) Rules, 1981, and shall come into operation on the 20th day of March, 1981.

2. In these Rules, unless the context otherwise requires

   “fish culture” means any activity involving the maintenance, propagation and promotion of the growth of fish in captivity or upon the sea bed within the territorial waters of Singapore;

   “fish culture farm” means any establishment or site in which fish culture is carried out and includes all structures and equipment within the establishment or site;

   “licence” means a fish culture licence issued under these Rules.

3. No person shall erect, operate or maintain a fish culture farm except under and in accordance with the terms and conditions of a licence.

4. The Director may designate areas within which fish culture may be carried out and may specify the type of fish to be cultured in each fish culture farm.

5. An application for a fish culture licence shall be in such form as the Director may determine.

6. (1) The Director may issue a fish culture licence in such form as the Director may determine.

   (2) The licence shall be subject to the conditions set out in the Schedule to these Rules, unless expressly excluded in such licence by the Director.

   (3) The Director may refuse to issue a licence or may vary or impose such other conditions as he thinks fit or revoke any licence already issued without assigning any reason therefor.

7. The fee for a licence shall be five hundred dollars for each five thousand square metres or part thereof for a period of one year or part thereof, expiring in every case on the 31st day of December, of the year in which it is issued.

8. The Director may, before issuing a licence, require the applicant to furnish a deposit to ensure compliance with these Rules and the conditions of the licence. The amount of deposit shall be five thousand dollars for each five thousand square metres or part thereof of fish culture farm.

9. In the event of doubt arising as to the correct description of the types of fish cultured under the licence, the name or the description given by the Director shall be deemed to be final and correct.

10. The Director may in his discretion restrict the number of licenses which may be issued in any area and in respect of any type of fish to be cultured.

11. (1) The licensee shall, upon expiry or revocation of the licence or when he ceases to operate the fish culture farm, remove forthwith, or within such time as a fishery officer may direct, any structures and any poles, anchors, floats and ancillary equipment used for fish culture.

    (2) Where the licensee fails to comply with paragraph (1), the fishery officer may remove or demolish the structure and any expenses incurred thereby shall be deducted from the deposit made under rule 8.

12. (1) No person shall be employed on any fish culture farm or be engaged in any activity thereon unless he is registered for such employment by the Director.

    (2) An application for such registration shall be in such form as the Director may determine.

    (3) The Director may either refuse to register or register the applicant subject to such conditions as he may think fit to impose or revoke the registration of a person without assigning any reason therefor.

    (4) The fee for such registration shall be five dollars for each person.

    (5) A person registered under this rule shall observe all directives which the Director may issue from time to time.

13. The Director may if he thinks fit exempt any person from all or any of these Rules.

THE SCHEDULE
CONDITIONS

1. The licensee shall use the site allocated to him solely as a fish culture farm and for no other purpose.

2. All structures in the site allocated shall be constructed or installed only in accordance with plans approved by the Director and any directive which may be issued by the Director. Any addition or alteration to the structures shall only be carried out with the prior written approval of the Director.

3. The licensee shall maintain his fish culture farm in good condition and ensure that the waters at and around his farm are clean and pollution free at all times.

4. The licensee shall display on the fish culture farm such identification marks as may be prescribed by the Director to denote that it is a licensed fish culture farm.

5. The licensee shall ensure that his fish culture farm is lighted at night to the satisfaction of the Director.

6. The Director or any person authorised by the Director shall have reasonable access to the fish culture farm for the purpose of inspection.

7. If the structure or any part thereof at the fish culture farm is, in the opinion of the Director or any person authorized by the Director, causing obstruction or impediment to navigation or development of port and other facilities, the licensee shall, within one month of a written notice by the Director, remove such structures or any part thereof. The removal shall be carried out at the licensee's own expense.

8. The Director or any person authorized by the Director shall carry out a survey of the fish culture farm after all structures referred to in condition 2 have been constructed or installed or after any structure or part thereof referred to in condition 7 has been removed. The cost of such survey shall be borne by the licensee.

9. The licensee shall within forty-eight hours inform the Director if he ceases to carry out any fish culture.

10. The licensee shall surrender his expire licence before a new license is issued to him.

11. The licensee shall observe all directives which the Director may issue from time to time.

12. The licensee shall at all times carry with him the licence and shall on demand by a fishery officer produce it for inspection.

13. The licensee shall furnish such information on his fish culture and any other information relating to fish culture as may be required by a fishery officer.

Made this 10th day of March, 1981.

KOH CHER SIANG
Permanent Secretary
Ministry of National Development
Singapore

Annex B

CONDITIONS OF ISSUE OF FISH CULTURE FARM LICENCE