H. H. Hanafi, M. A. Arshad and S. Yahaya, Fisheries Research Institute, Department of Fisheries, Penang.
Marine finfish culture in floating net cages is commonly practised in Malaysia.
The paper highlights some of the major sources of environmental pollution in Malaysia and their possible impacts on aquaculture activities. Simultaneously, the unrestricted use of the aquatic environment for some aquaculture activities has resulted in a deterioration of aquatic resources. Both of these factors can threaten the targeted aquaculture development of the nation. In this report, existing acts and regulations are reviewed to give a better understanding of the Malaysian Government's policy towards the protection of the environment and the aquaculture industry. Some recommendations which may help to reduce problems (or stop them escalating) and maintain the present aquaculture development are put forward, together with an in-depth study on marine finfish cage culture and cockle culture.
The expansion of aquaculture in Malaysia is being increasingly constrained by problems closely linked to the environment. Most environmental problems arise from impacts of land based developments and aquaculture activities themselves on the aquatic environment. Deteriorating water quality has been identified as one that escalates disease outbreaks and contamination of aquaculture products, resulting in dramatic economic losses to existing aquaculture activities. In 1992, the marine finfish cage culture industry experienced a tremendous economic loss when the main cultured species, mainly groupers and seabass, were suspected to be infected with vibriosis. In one case, a cage fish farmer in Penang reported a loss of MR 3,000 a day.
Map of Malaysia.
There have also been conflicts between fish farmers and other users of coastal and inland water resources. As a result, the Government has initiated a programme aiming to establish specific areas or zones for aquaculture and enforcing certain rules and regulations that will help to minimise their impacts. The negative environmental (and social) impacts of aquaculture and its poor economic performance have highlighted the major deficiencies in environmental assessment, planning, monitoring and control strategies for aquaculture in Malaysia. There is also rising concern over the short term economic benefits of aquaculture, which may be offset by degradation of natural resources and socio-economic impacts caused by indiscriminate and poorly planned aquaculture development.
3. STATUS OF AQUACULTURE
The fisheries industry in Malaysia produces about 980,000 tonnes of fish annually of which 7% (65,000 tonnes) of the total landings is from aquaculture. Inland aquaculture at this moment does not contribute significantly to the aquaculture industry and was only 17% (4,500 tonnes) of the total aquaculture production in 1991. About 20,000 people are directly involved in the aquaculture industry. The fisheries sector is also important since it provides about 60% of the animal protein intake of the country.
3.2 Status and development of aquaculture in Malaysia
Table 1 shows the development and status of the industry from 1987 to 1991 based on the Fisheries Statistics of the Department of Fisheries, Malaysia. The development potential of the industry is still vast in view of the Government's support and the available resources. A recent study has also indicated that there is still a substantial area available for the development of various aquaculture activities (Table 2).
Table 1. Aquaculture production in Malaysia, 1987–1991.
|Total Production (tonnes)||46,937||46,910||54,833||53,303||64,844|
|Value (000s RM.)||27,065||37,030||43,212||33,820||51,779|
|Production as % of GNP||0.03||0.04||0.04||0.03||0.04|
|Export earnings||RM. 739.7 millions in 1991|
(note: RM. 2.6 = 1 US $)
Table 2. Inland and coastal resources of Malaysia.
|Freshwater Lakes and Reservoirs||91,600 ha|
|Rivers and Streams||5,743 km|
Note: * Including Sabah and Sarawak.
** Taking into account the expansion of reservoirs.
3.3 Existing aquaculture practices in Malaysia
Several aquaculture systems have been successfully operated in Malaysia. These include: cockle culture on coastal mudflats; marine prawn or finfish culture in brackishwater ponds; culture of coastal finfish in floating net cages; mussel or oyster culture on floating rafts; freshwater fish and prawn culture in ponds or other waterbodies; and freshwater fish culture in floating net-cages or pens. Hatcheries and nursery systems for the production of some of the cultured species are also in operation. The list of species cultured, main culture practices and their respective culture systems being practised are shown in Table 3.
3.4 Supply of inputs to the aquaculture industry
3.4.1 Freshwater fish/prawn culture
Freshwater fish culture in Malaysia was started by farmers more than 50 years ago. Progress was, however, slow in the early years and significant expansion only took place after 1957. Some of the freshwater species like the goby (Oxyeleotris marmorada), freshwater catfish (Clarias sp), river catfish (Pangasius sp), freshwater eel (Fluta alba), giant freshwater prawn (Macrobrachium rosenbergii) and tilapia (Oreochromis sp.) are cultured in Malaysia under monoculture conditions, depending mainly on extraneous feeding. Most of the freshwater fish such as bighead carp (Hypophthalmichthys nobilis), mud carp (Cirrhinus mulitorella), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), silver carp (Hypophthalmichthys molitrix), black carp (Mylopharyngodon piceus), Javanese carp (Puntius gonionotus), the river catfish (Pangasius pangasius) and also the giant freshwater prawn are, however, grown under polyculture with the pond stocked with a suitable combination of different fish species.
Table 3. Species cultured in Malaysia, production and value.
Oreochromis sp. (black)
nd = no data.
The majority of fish cultured or stocked are planktonic feeders and/or herbivores feeding directly on the primary production of the pond. For the carnivorous fish species, low grade fish or animal offals and (at times) formulated diets are normally used as feeds. The supply of most of the freshwater fish fry comes from hatcheries except for some species which are being imported. Fry supply for some species, such as Oxyeleotris marmorada, are still collected from the wild.
The culture of the Malaysian giant freshwater prawn Macrobrachium rosenbergii in ponds is either done under polyculture or monoculture conditions. Fry come mainly from hatcheries which still prefer to use wild broodstock to maintain hybrid vigour. Pellet feeds are usually available for feeding the prawns but some farmers still utilise trash fish and animal offals as an alternative or supplement. Most of the freshwater farms, especially ponds and hatcheries, utilise river water except for a few (including the largest freshwater eel farm in Malaysia) which tap underground water sources.
3.4.2 Marine fish and shrimp culture
Marine finfish culture can be carried out in cages or ponds, but shrimp culture is normally done in ponds in Malaysia. The main species of marine/brackishwater fish presently cultured are seabass (Lates calcarifer), grouper (Epinephelus sp.), rabbit fish (Siganus sp.), mangrove snapper (Lutjanus johnii) and red snapper (Lutjanus argentimaculatus). There have been some introductions of exotic species from Taiwan such as the pompano (Trachinotus blochii). Cultured crustaceans include the tiger prawn (Penaeus monodon), the banana shrimp (P. merguiensis), the swimming crab (Portunus pelagicus) and mud crab (Scylla serata). The other crustacean being cultured in Malaysia is the spiny lobster, but this is only a small scale and for “holding” operations prior to marketing.
The culture of grouper and snapper (Lubajus sp.) still relies on wild caught seeds. The technology for the artificial production of seabass has been established for some time. Although there has been some recent development of artificial diets for cultured species, trash fish is still the main feed used. The mud crab and the swimming crab have been successfully bred by government hatcheries but yields are still inconsistent. Most farms collect juveniles (especially mud crab) from the wild for fattening and they are usually fed on trash fish.
Shrimp fry, which is comprised of the tiger prawn (P. monodon) and the banana prawn (P. merguiensis) are hatchery produced. They are cultured largely in dug-out ponds and fed with pellet feeds. The supply of seeds for the spiny lobster culture comes from the wild and they are fed with trash fish.
3.4.3 Mollusc culture
Mollusc seed, especially for species such as cockle (Anadara granosa) and mussel (Perna viridis), are generally collected seasonally from the wild at natural spatfalls. Demand for the more popular cultured mollusc, oyster (Crassostrea iredalei), however, will soon be met through artificial hatchery propagation.
3.4.4 Restocking programme
Since 1988, there has been some restocking by the Government particularly of freshwater bodies such as lakes and reservoirs (especially ex-mining pools) and some estuarine or enclosed sea areas. The main aims of the programme are to sustain and increase fish stocks, to protect and sustain the existing stocks and to encourage recreational fisheries in those waterbodies in line with the agrotourism concept. The main species involved are as listed in Table 4 with a target set to 100 million fry per annum. The source of fry for restocking is from government hatcheries throughout the country.
Table 4. Species involved in the Government restocking programme.
|Freshwater||Snakeskin gouramy (Trichogaster pectoralis); River carp (Leptobarbus hoevenii; Hampala macrolepidota); catla (Catla catla); catfish (Clarias sp); river catfish (Mystus sp); giant freshwater prawn (Macrobrachium sp); tilapia; bighead carp (Hypophthalmichthys noblis); mud carp (Cirrhinus molitorella); grass carp (Ctenopharyngodon idella); common carp (Cyprinus carpio); silver carp (Hypophthalmichthys molitrix); black carp (Mylopharyngodon piceus); Javanese carp (Puntius gonionotus); and river catfish (Pangasius pangasius).|
|Marine/Brackish water||Seabass (Lates calcarifer); tiger prawn (Penaeus monodon); banana shrimp (Penaeus merguiensis); swimming crab (Portunus pelagicus); mud crab (Scylla serrata).|
3.5. Present production
The 1991 fisheries statistics indicate that there is an overall increase in aquaculture production in Malaysia. Total production stood at 64,844 tonnes compared to 52,303 tonnes in 1990, an improvement of about 23.9 %. The increase in production from the marine sector was 26% as compared to freshwater which recorded an increase of 14.4%. Cockle production contributed almost 30% in the marine sector followed by pond culture (11%) and cage culture (3.6%). The freshwater production increases (about 15.7%) came from the pond systems which is partly due to the initiation of eel culture by a Taiwanese group. The total production and monetary value of the cultured species are 64,844 tonnes and RM. 52 million, respectively, with aquarium fish making up RM. 14 million.
3.6 Legal framework
The laws and regulations that deal with access to aquaculture are:
Fisheries Act, 317 of 1985.
Fisheries (Marine Culture System) regulations, 1990.
Fisheries (Cockle Culture) regulations, 1964 (as amended in 1982).
Environmental Quality Act, 127 of 1974.
National Land Code, 56 of 1965.
Important things to note here are that the Fisheries Act operates a distinction between aquaculture in riverine waters and in marine waters and that this distinction is based on the location of the culture system and not on the type of the water (fresh, sea or marine) used. It provides for a license system for marine culture systems but not for aquaculture in riverine waters (it gives the State Authority the power to promote and regulate the development of this activity). The legislation concerning freshwater management, as far as riverine aquaculture is concerned, is left to the state and the situation and complexity of the regulations may differ from state to state.
With the introduction of the Fisheries Act 1985 (Fisheries (Marine Culture System) Regulations 1990) regulation procedures for culture systems in the maritime waters of Malaysia also come into force. Under this act, aquaculture is defined as “the propagation of fish seed or the raising of fish through husbandry during the whole or part of its life cycle” and “culture system” as “any establishment, structure or facility employed in aquaculture and includes bottom culture, raceway culture, raft culture, rope culture and hatchery”.
The Director General of Fisheries (DGF) may refuse to issue, renew, cancel or suspend a licence for a certain period, usually for the following reasons:
For the purpose of proper management of any particular fishery (including aquaculture) “in accordance with the fisheries plan applicable to that fishery and with any of his directions” (sec. 13(1));
For breach of any provisions of the Act or any condition of the licence (sec. 13(3)). The DGF's decision are applicable to the Minister.
Lately, the Department of Fisheries has started working on extending the licensing and permit regulations to encompass freshwater areas under the state's jurisdiction and it also plans to introduce a “code of practice” for aquaculture activities. The Environmental Quality Act No 127 (1974) constitutes a basic instrument providing for a common legal basis to co-ordinate all activities of environmental control. There are currently some 34 pieces of legislation which contain provisions or references which are directly or indirectly related to environmental matters. Some of them are likely to offer to the fish farmer recourses or remedies where the water supply to his farm is impaired by pollution, or where he is suffering losses from external pollution. However, much of it is devoted to the tools which are available for the fish farmer to obtain protection, remedies or compensation for having suffered an injury due to major sources of water pollution (such as industrial and agricultural pollution or pollution arising from improper treatment of sewage). Obtaining compensation for injury caused to a fish farm and obtaining a court order to prevent further damage being caused by a source of pollution, are likely to be based on principles of civil law and rely on the recognition of civil liability of the presumed polluter(s). Some responsibilities may also rest with the administration under legislation relating to the management and protection of water resources, which could result in judicial action where the administration had not fulfilled its statutory duties. For instance, under the Land Conservation Act, 3 of 1960, the competent authorities (“collector”) have certain duties with regard to the protection of land and water sources from soil erosion and siltation (physical pollution).
3.7 Malaysian government policy towards aquaculture
The formulation of the National Agriculture Policy in 1984 by the Government of Malaysia for the development of agriculture has included, among other things, the development of fisheries and aquaculture up to the year 2000. This policy has been prepared on the basis of a balanced, harmonious and sustained growth rate in agriculture in relation to other sectors of the national economy. Such development should also be able to conserve land, water, plant and animal resources, is environmentally non-degrading, technically appropriate, economically viable and socially acceptable. The targeted development in the fisheries sector, both capture and aquaculture, is expected to meet the demand for the fish which is estimated to be about 250,000 tonnes by the year 1995 (Liong et al 1987).
4. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: GENERAL REVIEW
With the development of the other competing industries in some areas, increased discharges into aquatic resources and subsequent impacts on the environment, the development of aquaculture will be hampered. At the same time, environmental degradation due to pollution resulting from aquaculture activities is also evident and has led to a negative impression of the industry which may retard its growth. Clear and effective policies with good planning and foresight, based on a reliable database is very much required in order to ensure not only the continuous growth of the aquaculture industry, but also the other competing industries in Malaysia.
4.1 Impacts of external environment on aquaculture production in Malaysia
4.1.1 Inland aquaculture
Problems of flooding, variable water availability and siltation are some of the common physical problems normally encountered by aquaculture farms, particularly those located in the vicinity of development activities. For example, since 1980 the Freshwater Fisheries Station of the Department of Fisheries, Malaysia at Bukit Tinggi, Selangor has experienced problems when housing development was carried out upstream. The main impact was on water quality, especially during the rainy season when the amount of suspended solids, carried downstream was very high. The problem worsened as sewage from the houses flowed into the river system. As a result, fry production by the centre declined and, as expected during the drought season, the river system had very little water due to the depletion of the forest watershed which was removed for the housing estate. It was also reported that some of the indigenous fish species such as the sebarau (Hampala macrolepidota) had disappeared and the guppies, which at one time served as food for this fish species, have become abundant (Gopinath, pers. com., 1993).
The construction of hydroelectric dams in some major rivers has obstructed the migration of fish and freshwater prawns and with significant effects on the stock levels. The depletion of the Malaysian giant freshwater prawn in the Prai River was a typical example until remedial action was taken to restock the river with the fingerlings. However, the programme can only ensure that stocks are maintained, not the natural propagation of a particular species which needs both freshwater to grow and mature and brackishwater for its larval stages.
Temperature fluctuations, and the presence of highly acid or alkaline soils are other physical factors that may act as constraints to aquaculture development in some areas of Malaysia.
Toxic industrial wastes
Malaysia is presently undergoing rapid industrial development and there have been incidences of toxic pollution from industry, which probably affect aquaculture. For example, the Freshwater Fisheries Research Centre of the Department of Fisheries monitored the quality of their freshwater source, Sungai Mehka, from 1968 to 1988. Based on these findings and a report published, it was found that water quality in the river had been polluted by increasing industry, settlement and land based agricultural activities along the river. Some of the parameters such as conductivity (165 ppm), total ammonia (5.85 ppm), phosphate (0.78 ppm) and alkalinity (50 ppm) has reached dangerous levels and can cause fish mortality (Maznah, 1988). In one case a nearby rubber factory processing liquid rubber and discharging its waste into the river, has been identified as one of the contributors to pollution.
Human and agricultural wastes
Urbanisation, increases in population density and the intensification of agricultural activities in certain areas are among the main causes of water pollution (Department of Environment, 1991). Where no proper monitoring and control is imposed, discharges resulting from these activities can result in eutrophication, phytoplankton blooms and low dissolved oxygen levels. High levels of pollutants, including ammonia and sulphides, which are especially deleterious to fish life, have been reported in effluent waters from rubber and oil palm factories. The management of water quality solely by regulating and licensing of effluent discharges via the effluent discharge standards present certain constraints. Specifically, cumulative pollutant loads may eventually exceed safe levels, or the assimilative capacity of the rivers, despite the fact that effluent discharges are in compliance with discharge standards. More often than not the levels of pollutants are too high for fish or other aquatic life to remain unaffected. However, steps are already being taken to remedy the situation by introducing different standards, e.g. for fish life, that could be enforced in accordance with specific areas.
There have been tremendous changes in the paddy field aquatic environment over the last three decades owing to increased use of fertilisers and potent pesticides, which has caused a rapid decline of paddy-field fishes. It is also believed that deteriorating water quality has further enhanced the outbreak of epizootic ulcerative syndrome (EUS) in these fish populations (Akhir, 1990). In 1981, there was an outbreak of EUS among fish in the rice growing areas, particularly in the four northern states of peninsular Malaysia. The fish were of economic importance, in particular to rice farmers, as it is an important dietary component. In a report by a working committee set to look into the problem, it was indicated that the primary cause was water pollution by toxic pesticides and fertilisers.
There are no reports of oil spills or other petrochemical discharges affecting inland aquaculture.
To date there has been no report of this nature affecting freshwater aquaculture or inland fisheries in Malaysia.
4.1.2 Coastal aquaculture
As the coastal area is the ultimate receptacle of run-off and waste waters, agriculture land use run-off and effluents from power stations (particularly after cleaning activities such as chlorinated water and spillages of fossil fuel), aquatic species are bound to be exposed to toxic substances, such as organochlorines, heavy metals and pesticides. According to the Environmental Quality Report (Department of Environment, 1990), Malaysian coastal waters are mainly contaminated with oil and grease, faecal coliform and suspended solids. This would imply that most coastal aquaculture activities such as cockle culture and finfish culture in floating cages would be exposed to these elements.
Activities such as land reclamation and mining have had some impact on coastal aquaculture by causing increased siltation of riverine and coastal waters. It also has brought about negative impacts on bottom-dwelling aquatic fauna which can suffocate and result in the decline of populations. It was reported that high sediment loads, along with increased organic inputs, have resulted in the destruction of the natural estuarine oysters in some of the west coast estuaries of peninsular Malaysia (Jothy, 1984) and Sabah.
Other coastal development activities, such as the construction of flood control structures (e.g. barrages) have resulted in variable water availability for freshwater and estuarine finfish culture in cages (besides preventing the natural migration of the endemic species such as the giant freshwater prawn). These barrages are used to prevent water flowing downstream for lengthy periods, and are occasionally lifted, thus flushing the marine finfish cages with huge quantities of fresh and/or polluted waters. The fluctuation in salinity from large rivers is another significant constraint to the development of coastal aquaculture in some areas. Cage reared marine finfish and molluscs are frequently exposed to wide salinity fluctuations, with salinity decreasing to critical levels during the rainy seasons and sometimes resulting in fish mortalities and heavy economic losses (as at Jubakar in Kelantan, Kuala Gula, Perak and Sungai Udang in Penang). Liong et al (1987) reported mass mortalities of cockles reared in the Kuala Juru areas due to the lowering of salinity. Further development of aquaculture activities in such areas will be unsound and the existing aquaculture activities will often face mass mortalities of the cultured fish and significant economic losses.
Acid sulphate soils are widespread in the coastal zone of Malaysia and the clearance of mangroves for agriculture and other activities has led to acid sulphation of the soils. The release or run-off of acidified water from these areas has occasionally resulted in large-scale fish and prawn kills in the states of Perak and Johore.
Toxic industrial wastes
The release of toxic industrial waste have had some localised impact on coastal fisheries. There have been reports of the disposal of toxic waste and a follow up investigation by the relevant agencies, including the Department of Fisheries, Malaysia, is underway.
Human and agricultural wastes
Faecal contamination in the coastal waters off the west coast of peninsular Malaysia in some parts has exceeded the proposed interim standard for recreational areas of 100 MPN/100 ml of coliform bacteria (Department of Environment, 1990). Most of the pollutants come from domestic effluent and agro-based industries such as pig farms, which generate large quantities of waste and discharge directly into estuaries and tidal rivers without any pre-treatment. The development of aquaculture is unsuitable in these areas and existing aquaculture activities may face mass mortalities of cultured fish stocks and heavy economic loss due to the effects of nutrient enrichment (low dissolved oxygen and phytoplankton blooms) as well as high levels of bacterial contamination of aquaculture products.
The finfish cage farms in Kukup, south-west Johor, have been reported to have suffered from exposure to an oxygen deficient water mass resulting from the above pollutants. A study was carried out to monitor the level of contamination by bacteria of faecal origin (Ismail, 1988) at three major cockle producing areas under the national programme in 1986. It was found that the harvested cockles in one area, (Penang) had a rather high FC/MPN of about 250 and the source was traced to the discharge of human excreta into the adjacent sea. The Government acted promptly by banning the harvesting and further culture of cockles in the areas identified.
Organic and nutrient loadings in coastal waters have frequently generated planktonic blooms and red tides causing high oxygen demand in the water and leading to fish kills. The planktonic organism involved is a non-toxic dinoflagellate, Noctiluca miliaris. In addition, red tides caused by the toxic dinoflagellates, Pyrodinium bahamense var. compressa have occurred in Sabah since 1976 (Jothy, 1984). Recently, as a result of a food poisoning case in Sebatu, Melaka, the Department of Fisheries carried out a study in the coastal areas in the vicinity and detected a red algal bloom in the region where the mussel culture industry is situated. As a result, the department has put a ban on the harvest and consumption of mussels in the areas involved.
The Environmental Quality Report (Department of Environment, 1990) indicates that Malaysian coastal waters are largely contaminated with oil and grease. These have been reported to have affected finfish cages in Kukup in 1987 (pers. obs.).
There are no reports of this nature affecting aquaculture in Malaysia.
4.2 Contamination of aquaculture products
Harmful wastes discharged from land based activities may also have negative effects on aquaculture products. Chemicals, heavy metals and bacterial (microbial) contamination of fish products will result in the decline (or total ban) of consumption of the affected products, or will incur a greater product cost as in the case of bacterial contamination in mollusc, which will have to be processed for safer consumption. Heavy metals have been detected in marine finfish products by the Department of Fisheries, but at very low levels and do not pose any health threat. PCB levels in freshwater fish are still very low compared to the Swedish standards. Wild cockles, Arca sp. from areas such as Pantai Remis in Perak state in Peninsular Malaysia have been shown to have elevated levels of lead and cadmium. (PCB levels were however found to be low compared to Swedish standards).
Edible shellfish and cockles in particular, have been known to harbour significant levels of coliform bacteria and other microbial contaminants, especially those flourishing in areas of high organic load resulting from sewerage or other effluent discharges.
Over 300 cases of paralytic shellfish poisoning (PSP), including some human fatalities, have been reported in Sabah since 1976 and more recently, in Melaka, Peninsular Malaysia, in 1992 as a result of red tides caused by the toxic dinoflagellate, Pyrodinium bahamense var. compressa (Jothy, 1984). The State Fisheries Department of Sabah and Melaka are closely monitoring PSP levels in shellfish, in order to provide early warning signals to the public on the risks of shellfish consumption.
4.3 Impact of aquaculture on the environment
Aquaculture, which was once considered an environmentally sound practice, is now counted among potential polluters of the aquatic environment and the cause of degradation of wetland areas (Pillay, 1992). Accelerated development of coastal and inland aquaculture activities in the last decade together with intensification have resulted in the deterioration of water and sediment quality, particularly in the growing areas, due to self-pollutants from cultured organisms (such as metabolic wastes and faecal substances) and residues of feeds accumulated on the bottom sediments.
In Malaysia, aquaculture has an enormous potential for expansion and intensification and has been identified as one of the revenue earners. Without proper and adequate management of development, however, this may bring about an appreciable increase in the effects of its pollutants on the adjacent environment.
4.3.1 Inland aquaculture
Hypernutrification and eutrophication have been detected in enclosed water bodies such as lakes and reservoirs where intensive aquaculture (e.g. cage culture) is practised, especially over a period of time. This could result in decreased oxygen levels, algal blooms and the release of toxic metabolites (such as ammonia) and these problems are expected to become more severe in the future. However, to date no such serious occurrences have been reported or recorded in Malaysia.
Chemicals are often used in freshwater aquaculture, and there has not been any significant impacts of these agents on the environment. The main chemicals used in inland aquaculture in Malaysia are shown in Table 5. The use of chemicals may lead to the emergence of more bacterial resistance to certain antibiotics, as has been clearly observed recently at the Freshwater Fisheries Research Station, at Batu Berendam, Melaka (Ahmed Faris, 1993, pers. com.).
Table 5. Chemicals used in freshwater aquaculture.
|Chemical Name||Dose Rate||Purpose|
|Sodium chloride||1000–3000 ppm||Bacteriocide and parasiticide.|
|Methylene blue||5 ppm||Parasiticide.|
|Formaldehyde||25 ppm||Control of ectoparasites.|
|Malachite green||0.01 ppm||Fungicide and parasiticide.|
|Copper sulphate||0.1 ppm||Bacteriocide and parasiticide.|
Interaction between aquaculture and native species
Some stocks of wild freshwater fish have been severely depleted due to the widespread practice of capturing fry as seed for farming, or collecting the adults during the breeding season for consumption and spawning. The natural stock of indigenous species temoleh (Probarbus jullenii) in the Perak river has declined due to over fishing. The restocking of incompatible species may bring about the same effect and would also have some impacts on the wild gene pool. To date, however, no such observations have been recorded.
Social conflicts and aquaculture
The limited availability of water of optimum quality for aquaculture activities has resulted in severe competition with agricultural activities and (to a lesser extent) industry in Malaysia. In addition, many areas which have been identified or zoned as potentially suitable areas for aquaculture have been abandoned in view of existing or proposed “conflicting” industrial developments. The proposed requirement for implementation of Environmental Impact Assessment (EIA) and prior approval by the Department of Environment before any project can be implemented should curtail the problem but with strict adherence to the set regulations.
4.3.2 Coastal aquaculture
Some aquaculture practices, e.g. the construction of floating seed collectors, growout rafts and “behts” (bamboo pole fencing to corner and trap the fish) across estuaries, may result in obstruction of water flow and sedimentation in estuarine areas. The long-term effect of such practices has led to flooding in upstream areas and areas adjacent to the blocked estuaries. This is normally observed in the east coast of peninsular Malaysia and a government agency, the Drainage and Irrigation Department, has objected to the activities.
Both finfish cage farms and shrimp ponds produce wastes and/or discharge high loads of organic matter into the surrounding areas. This can result in eutrophication, low oxygen levels and algal blooms. The planned expansion of this sector is expected to lead to exacerbation of the problems, particularly when the carrying capacity of the areas concerned is exceeded. The development of coastal ponds for shrimp and finfish culture has also resulted, in some areas and on some occasions, in acid sulphation of the underlying soil, and leaching has led to a sharp rise in the acidity of pond water and streams in the vicinity. This can result in shrimp mortalities and affect other aquatic life in the nearby streams. In some cases, the seawater and/or brackishwater discharged from shrimp farms has also resulted in salinisation of surrounding areas, causing problems for aquatic life and freshwater users alike.
Chemical residues from aquaculture practices released into the surrounding areas, will endanger the surrounding habitat. Table 6 shows the chemicals currently used in coastal aquaculture in Malaysia. Introduction of these agents into aquaculture systems is often done without adherence to procedures recommended by the Department of Fisheries, Malaysia. The use of chemotherapeutants is generally at a low level and impacts on the environment may be assumed to be minimal. The indiscriminate use of chemicals may lead to the emergence of more resistant bacteria strains to certain antibiotics in coastal aquaculture, but this has not yet been observed.
Table 6. Chemicals used in coastal aquaculture in Malaysia.
|Chemical Name||Dose Rate||Purpose|
|Oxytetracycline||50 mg/kg fish||Systemic bacterial infections.|
|Chloramphenicol||50 mg/kg fish||Bacterial ulcers.|
|Formalin||50–100 ppm||Control of ectoparasites.|
|Malachite green||5 mg/litre||Fungicide and parasiticide.|
|Copper sulphate||1–4 mg/litre||Control of algae in fish and prawn farms. Bacteriocide and parasiticide.|
Impacts of coastal aquaculture on mangroves
In Malaysia, studies have indicated that the conversion of mangroves for industry and agricultural practices (such as oil palm cultivation) is of greater significant than aquaculture. Even so, large areas of mangrove forests have been cleared for the construction of shrimp farms. Based on updated reports, the total mangrove area utilised for the construction of shrimp farm in Peninsular Malaysia is less than 2,000 hectares.
The process of clearing the land, constructing pond systems and the subsequent discharge of effluent from the shrimp farms can cause significant deterioration of the surrounding ecosystems. This has already been experienced in countries like Thailand and the Philippines.
The development of shrimp farms in mangrove areas is still continuing despite the establishment of guidelines by the National Mangrove Committee (NATMANCOM, 1981) which specifically disallows the use of thriving mangrove areas for shrimp farming. There is a need to educate potential shrimp farmers and developers of the regulations and for stricter control to be enforced by the relevant authorities.
Interaction between aquaculture and native species
The use of mangrove areas and coastal water bodies for aquaculture purposes has caused concern over the consequences that may befall natural fish populations that use mangroves for breeding, nursery and feeding grounds. The transfer of disease between wild and cultured stocks is a potential problem apart from the new concern that there may be wild gene pool pollution by the stocked (or accidentally released) fish species. The introduction of new species through sea-ranching, especially in enclosed or semi-enclosed water bodies, can lead to the depletion of other in situ species.
Social conflicts and aquaculture
The limited number of sheltered sites for finfish cages and coastal areas for shrimp farms, has resulted in competition between aquafarmers for water and land space. There is also a limited degree of competition for coastal land resources, with agriculturists, industry, tourism and artisanal fishermen.
5. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: IN DEPTH STUDY
5.1 Culture of marine finfish/mussel/oyster in floating cages and rafts in Jubakar, Kelantan
5.1.1 The study site
The study site is located on the north east coast of peninsular Malaysia, in the state of Kelantan in a lagoon named Jubakar (Figure 1). The size of the lagoon is estimated to be about 5 km2 and it is connected to the open sea by an opening in its bordering sand bar. Four main rivers, the Sungai Kelantan (one of its tributaries), Sungai Kelaboran, Sungai Pengkalan Nangka and Sungai Tujuh flow into the lagoon. Four flood control gates and two culvert drains have also been constructed in the perimeter of the lagoon to control water levels in agricultural areas adjacent to the lagoon and, at the same time, stop the inflow of seawater into the agriculture areas. Additional drainage systems are constructed into the lagoon to drain the rest of the area including the village areas, especially during the monsoon period.
There are four main activities operating in the vicinity of the lagoon area: (i) recreation and tourism: i.e. chalets, restaurant and stalls; (ii) agriculture: i.e. paddy cultivation and tobacco planting; (iii) aquaculture and to a certain extent capture fisheries; and (iv) urban settlement (about 400 households).
Finfish cage culture
Aquaculture activities started in the lagoon in 1983. Culture systems consist of floating net cages which are used for the culture of grouper (Epinephelus sp.), seabass (Lates calcarifer), snapper (Lutjanus sp.) and red tilapia (Oreochromis sp.). Some of the floating rafts are utilised to support strings or plastic baskets for the culture of mussel (Perna viridis) and oyster (Crassostrea iredalei). The culture of finfish in floating net-cages has long been practised in Malaysia. The rafts, measuring 7m × 7m, are constructed of wooden beams. Each raft consists of four net cages measuring 3m × 3m with depths ranging from 1.5–2m. Plastic or polystyrofoam drums are often used as floats. Seabass and red tilapia fry are obtained from the local hatcheries or imported from neighbouring countries, especially Thailand. The fry of the other cultured species i.e. grouper and snapper are usually caught from the wild or imported from Thailand. Fish are fed with trash fish, with the exception of tilapia where commercial pellets are used.
Raft culture of mussels and oyster
Raft culture of mussels and oysters took off in 1986, after a successful transplanting project, initiated by the Department of Fisheries. There are signs, however, that the cultured species are susceptible to low salinity stress during the monsoon period (October-January) and some significant economic losses have been reported by the fish farmers. These problems can be overcome with proper timing and the culture can be economically operated. Jubakar Lagoon is a natural area for oyster seed in Malaysia. Mussel seed can also be collected naturally from the area, but culturists still have to rely on seed imported from more successful sites on the west coast of Peninsular Malaysia. Trials to start cockle culture were abandoned after several failures due to high mortalities, as a result of high salinity fluctuation and the changing nature of the substratum.
Figure 1: Schematic diagram showing the locations of the various activities at the Juvbakar Lagoon, Tumpat, Kelantan.
5.1.2 Impacts of the external environment on finfish and mollusc culture
Due to the many drainage and riverine systems flowing into it, water quality parameters in the lagoon and around the cages often fluctuate and deteriorate, especially during the heavy rainfall season (November to January). This is reflected in the monthly water quality results (from July 1992-February 1993), which are summarised in Table 7. Salinities would often drop drastically and suddenly (from 20 ppt to freshwater) due to excess water discharged from the flooded rivers and drainage systems, particularly during the monsoon season. The occurrence of salinity pockets in the lagoon is also frequent due to incomplete water mixing.
Table 7. Summary of monthly water quality parameters in Jubakar Lagoon at discharge points and fish farms, July 1992-February 1993 (see Figure 1).
|Location||pH||DO (mg/l)||Temp (°C)||Salinity|
Note: nd = no data
The occurrence of “salinity pockets” has often led to mortalities, including cultured mussels and oysters, which are “trapped” at the surface and cannot tolerate the sudden and/or extreme changes in salinity and long periods of exposure to the low salinity (less than 10 ppt). The fish and molluscs that inhabit the deeper part of the lagoon may, however, be able to survive and reproduce.
Water temperatures in the lagoon fluctuate seasonally with maximum temperatures of 33°C in the dry season and lowest temperatures of 27°C during the rainy season. These small changes in temperature will not have very significant effects on the cultured species. Water pH of the lagoon also fluctuates between 4.0 to 8.0. It was observed that, as in the case of salinity, pH pockets occur in specific areas of the lagoon depending on the influence of freshwater discharge from the riverine and drainage systems (Table 8). In one locality, pH levels were found to be low (6.2), even though the salinity was around 16 ppt. It is suspected that the freshwater discharged from the swamp area nearby (with a pH of 4.0) contributed to this phenomena. Dissolved oxygen (DO) data collected at the drainage discharge points indicate a lower dissolved oxygen pattern (as low as 1.3 ppm on certain occasions) than the water in the lagoon. Total ammonia levels also tend to increase at the discharge points, chalets and around the fish cages indicating that there is already some degree of pollution in the waters near these structures in the lagoon and that they are the sources of water pollution.
Table 8: Water quality in Jubakar Lagoon over a complete tidal cycle on the 10th and 12th February 1993.
|3. N. culvert.||27.2–29.9||10–15||6.4–8.6||5.1–6.2||62–78||0.1|
|6. S. culvert.||28.5–29.5||10–18||7.4–7.7||5.7–6.7||6.7–96||0.0|
|8. JPS 1.||29–30||7–14||5.7–8.0||7.0–8.0||36–61||0.0|
|9. JPS 2.||29–30||2–15||4.0–6.7||6.4–7.4||17–50||0.0|
Toxic industrial waste
There are some small ship building activities in the village nearby, but the expected pollution effect from this industry (such as oil sludge) is still insignificant.
Human and agricultural waste
There are two main types of agricultural activities found in the vicinity of the lagoon, paddy and tobacco planting. Paddy areas occupy about 300 ha while tobacco occupies about 850 ha. It was found that both of the cultivations use chemicals (herbicide, pesticides and fertilisers). The chemicals being used are shown in Tables 9 and 10. These chemicals or their residues will be washed and discharged into the lagoon before finally being released to the sea.
The molluscs from the lagoon have so far not been analysed for any chemicals that might have accumulated in the tissue of the cultured organisms. Other studies carried out in different areas within the waters of Peninsular Malaysia have, however, indicated that the levels of pesticides, herbicide and antibiotics in the tissues are still well below recommended safe levels.
Table 9. List of pesticides used by tobacco farmers in the District of Tumpat as recommended by the National Tobacco Board (NTB).
|Soil Fumigation||Basamid; Methyl bromide.|
|Herbicide||Nabu; Devrinol 2-E.|
|Biological||Bactospien; Dipel WP; Boboit WP.|
|Nematodicide||Curateer 3G; Combat 3G; Fudan 3G.|
|“Ceding” Remover||Royaltac-M; Off-Shoot T; Hading; Tamex.|
|Insecticide||Super-midaphos; Tamaron Special; Super Force 600; Protect 75; Tamaron Super; Multiphos; Karate; Ripcord 505.|
|Fungicide||Antracol 70 WP; Pivicur-N; Daconil 2787; Dryene 75 WP; CH Maneb; Tricarbamix; Daconil Flow 500.|
Table 10. List of pesticides and fertilisers used by paddy planters in Jubakar.
|Fertiliser||Urea||4–5g/m2 (twice per cycle)|
|Muriate of Potash||50g/m2|
|80:40:20 kg/ha (KADA)|
|90:50:40 kg/ha (acidic soil)|
|Chemicals||Lime||2 tonnes/ha (acidic soil)|
|Manganese dioxide||50 kg/ha|
|Copper, Zinc and manganese||Unknown|
|Calcium and magnesium sulphate||Unknown|
|4 DIBE + Herbicide||2.0 kg/ha|
|BHC (gamma)||1.0 kg/ha|
|Endosulphane||1.0 kg/ha (900 ml/ha)|
Besides agriculture, the other potential source of pollution are the urban areas (Tumpat township and Kampong Baru) and the chalets constructed for tourism purposes. A study of the faecal coliform level (FC-MPN) in water and tissues of oyster, cockle and wild clam in the lagoon has shown that there is some contamination by faecal bacteria. However, the levels are still within the acceptable range of the American Public Health Association (APHA). The source of contamination is probably the sewage discharges from domestic and animal rearing in the north and the chalets in the middle portion, which discharge to the lagoon. A study of the bacterial faecal count at the discharge point from the domestic wastes showed higher levels of faecal coliform in the water. Studies on the levels of BOD and ammonia in water around the lagoon showed that levels were higher at the floating chalets and domestic discharge points.
There may be traces of oil (diesel) discharged from fishing boats operating or anchoring in the lagoon. However, so far there have been no reports of any fish kills related to these discharges.
5.1.3 Impact of cage culture on the environment
Within the area available for cage culture, which is less than 0.5 km2, a total of 840 cages have been installed. Physical observation of the sea-bottom around the cages has shown some accumulation of organic wastes, most probably feed debris, from the cage culture activities over the 10 year culture period. Although there have been a number of reports of fish diseases occurring, no attempt has been made to correlate them with the sea-bottom condition. In the Republic of Korea, it was realised that progressive eutrophication caused by intensive cage finfish farms caused severe red tides with a lot of damage to fish, and that the accumulated self-pollutants caused by mollusc culture in a semi-closed bay (Chinhae Bay) created significant oxygen depletion in the water column and mass mortality of cultured and natural organisms. It is expected, particularly with the discharges from land based activities, that the sediment condition and water quality of the lagoon will not be able to support any more (or even the existing) aquaculture activities in the future.
The technique used in harvesting cockles cultured in the lagoon, i.e. the dredging system, has disturbed the natural condition of the sea-bed. This could lead to short and long term effects on water quality and fish fauna in the immediate area. It is expected that some benthic organisms may be affected by the increasing turbidity of the water, or will be dispersed in the surrounding waters and cages. The long term effect of the activity is yet to be monitored, although it is expected that the natural physics of the sea bed will be altered. Unused materials of fish culture such as nets and wooden structures, plus mollusc shells, were also found littered on beaches and sometimes in the water. At the moment, the effect on the water quality may not be significant but these materials can obstruct the current flow and at the same time harbour organisms which can be a threat to the cultured fish.
Some of the fish seed stock used in culture are imported from the neighbouring countries and done so without proper quarantine measures. There have been instances where the imported fry were infected with tail and finrot and stocked into the cages.
The introduction of mollusc culture in the area provides an intermediate host for bacterial and parasitic organisms in the vicinity. A preliminary study has indicated that the oysters cultured have been the host of the parasite Cryptocaryon sp. which has caused white spot disease in the cultured fish resulting in mass mortality. So far there has been no real study as to whether the wild fish stock in the lagoon have been similarly affected.
For the moment there is very little use of chemicals and antibiotics.
Social conflicts and aquaculture
There have been a number of fishkills and project failures and the fishermen usually place the blame on discharges of freshwater and pesticides from agricultural areas. A number of post-mortem studies have been carried out by various government agencies, including the Department of Fisheries, and it has been identified that the most probable cause is the sudden, drastic changes in salinity due to flushing. It has been suggested that the timing of the culture period needs to be adjusted so as not to coincide with the monsoon season. The introduction of diseased fish fry by some fish farmers has also brought complaints from others with uninfected fish in their cages. The Department of Fisheries started to implement the quarantine regulations to minimise the importation of diseased fish in 1992.
5.1.4 Legal framework for the environmental management of aquaculture in relation to cage culture
Under the Fisheries Acts, any person wishing to engage in a marine culture system must respect the following procedural steps and obtain the following authorisations:
Site identification by the farmer;
Application to the Director General of Fisheries (DGF) for a “permit to set up a marine culture system” in a proposed site; and before issuing the permit the DGF requires the applicant to pay a deposit in respect of the marine culture system (Fisheries (Marine Culture System) Regulations, reg. 3 and 5);
Application to the District Office for a Temporary Occupation Licence to occupy the site specified in the application (The National Land Code, 1965, Chapter 2 of Part IV); and finally,
Application for a licence to operate a marine culture system; (The Fisheries Act, 1985, sec. 1 1(3) a and the Fisheries (Marine Culture System) Regulations, reg. 6).
Depending on the type of culture system used, the deposit and the fees may vary and specific terms and conditions will be attached to the permit and the licence issued by the DGF set out in the schedules of the Fisheries (Marine Culture System) Regulations, 1990. This is the case for the following culture systems: rack; pole; raft; cage; pen; and on-bottom, as well as hatcheries and nurseries. The conditions which the DGF may impose in issuing a permit and a licence for marine cage culture are as in Table 11.
With regard to Environmental Laws related to the activity of transportation shipping, transportation of petroleum by ships and transportation of petroleum by pipelines in the marine environment there are two relevant acts, the Petroleum Safety Measures Acts 1984 and the Petroleum (Safety Measures) (Transportation of Petroleum by Pipelines) Regulation 1985. For shipping and pollution from ships, Merchant Shipping Ordinance 1952 (part VA) Environmental Quality Act 1974 and Exclusive Economic Zone Act (1984). The aim of these Acts is, firstly to be able to control and/or reduce environmental impacts on activities such as aquaculture, and secondly, to have an effect on the cost effectiveness of the industry and the implications it will have on the growth and development of aquaculture in the near future, thus meeting the objectives of the government.
5.2 Cockle culture - on bottom culture in Kuala Juru, Penang
Cockle culture is one of the main aquaculture industries in Malaysia with a production of about 40,000 tonnes in 1991 (from an area of 5,541 ha) and it extends over a number of states, including Perak, Selangor and Penang. Research is continuing to expand the culture areas through transplanting trials in pre-selected areas in line with the development programme to expand the shellfish industry, particularly on the production of the blood cockle. In this context, the Department of Fisheries has drawn up a programme to increase new areas for bivalve culture. A total of 18 new sites were selected in 1989 for the transplantation of cockles with the authorisation of the respective State Authority
5.2.1 The study site
The study site is located on the north west coast of peninsular Malaysia, in the state of Penang and within a coastal mudflat in the Juru district (Figure 2). The total area involved is about 100 ha with around 38 participants. The site is located adjacent to industrial areas which were reclaimed from mangrove. The types of industry presently in operation include: electronics; textiles; basic and fabricated metal products; food processing and canning; processing of agricultural products; feed mills; chemical plants; rubber based industry; timber based wood products; paper products and printing works; and transport equipment. Other main activities that are operating in vicinity of the culture area are a ships' harbour with petroleum unloading and a red earth quarry which extends right up to the coastline. There are three main rivers flowing into the area, Sungai Juru, Sungai Semilang and Sungai Jejawi where some fishing villages are situated (Figure 2).
Table 11. Conditions which the DGF may impose in issuing a permit and licence for finfish cage culture.
|Permit for finfish cage culture.||1.||Use of structure and equipment.||Only one shelter per cage and size is specified by the Fisheries Officer (FO).|
|2.||Location/site.||No re-siting or removal without the written permission of the DGF. Minimum distance of 20m between two licensed culture sites, except with DGF Authorisation.|
|5.||Records of aquaculture activities.|
|6.||Disclosure of information.|
|7.||Other conditions.||Demarcation of boundaries by poles painted fluorescent white. No obstruction to navigation; Such other conditions as the DGF may specify; 3 months to set up the cage culture system unless longer is authorised by FO; Within 21 days the fish farm must apply for a licence to operate the cage culture system.|
|Licence||8.||Location/site.||No re-siting or removal without the written permission of the DGF.|
|9.||Disease.||Immediate report of any disease outbreak in culture system to DGF.|
|10.||Disposal of dead fish material or wastes.||Strict compliance with any directions on sanitation and fish health likely to be imposed by the DGF.|
|12.||Monitoring and control of water quality.||Obligation for fish farmer to control water quality as not allowed to harvest or sell fish raised in polluted waters, or waters infected by any substance or organism harmful to human health obligation to allow for monitoring activities to be undertaken by the DGF for research purposes or investigation. No obstruction to navigation.|
|13.||Movement of fish.|
|14.||Other conditions.||3 months within which the marine culture system must be in operation.|
Control of water quality for purposes of protecting human health.
Obligation to allow for visit or inspection by any fisheries officer.
Other conditions as specified by the DGF.
The culture sites were demarcated using erect poles. The sea bottom was cleaned of unwanted debris prior to transplantation of cockle seedlings. Cockle seeds (about 5,000 shells/kg) were obtained from natural spatfall areas in Sungai Besar, Selangor and from Kuala Gula and Lekir, Perak and transported in recycled feed bags by commercial lorries to the culture sites. Transportation was usually carried out in the late afternoon, to avoid mass mortality during transportation. Stocking densities used were between 100–200 tins (1 tin = 18 kg) depending on size of seeds and location of transportation sites. On average, for a site of 20 ha about 4000 tins or 1000 bags (72 tonnes) of seeds are required, however, the stocking density used by private culturists is believed to be at least double the amount used in the above projects.
Figure 2: Schematic diagram showing the locations of the various activities at the Kuala Juru, Seberang Prai, Penang.
The implanted cockles were allowed to grow for some 8–12 months before harvest. During this time, routine management included spreading/thinning and culling of the cultured cockles using a mechanical dredge locally known as a “kor”. Harvesting of the cockles is carried out using a “kor” with a smaller mesh size.
5.2.2 Impacts of the external environment on cockle production
One of the most common factors that causes mass mortality of cockles in their culture areas is the desalination of seawater due to freshwater influx from rivers or drainage systems. Cockles thrive well in estuarine areas due to high primary productivity and optimal salinity, but they are also exposed to sudden changes in water quality caused by large freshwater discharges. Cockle culture at Jubakar is subject to varying salinities due to its proximity to the flood gates, located about 0.5 kilometre from the culture areas. As a result, the cockle culture trials carried out there in 1989 (Ng, 1990) were unsuccessful.
On a much bigger scale, the loss of cockle due to the lowering of the salinity at a site in Juru, Penang on one occasion was estimated to be close to a million Malaysian Ringgit (RM.). Apart from that, and due to the extensive areas and hence the total biomass of the dead cockles, the adjacent water and coastal substratum quality in the vicinity was found to be high in sulphide which could have had some significant impact on the existing aquafauna in the involved area.
Heavy siltation from rivers due to land development also poses a great hazard to the cockle industry as the silt carried down into the coastal area can change the substratum structure and/or “blanket” the cockles.
Toxic industrial wastes
Cockles are filter feeders and capable of accumulating high levels of pollutants without affecting their growth and survival. However, they could pose serious health hazards if the levels of pollutants accumulated in their tissue exceed the safe level for human consumption. There have been sudden occurrence of cockle mortalities, but the cause has not been identified. Some claims have been made by the fish farmers that they have been affected by industrial wastes coming from the industry, although without sufficient qualitative and quantitative evidence. To date, levels of heavy metals in cultured cockles have been found to be below the permissible limit. However, there have been cases where the wild cockles Arca sp. in Pantai Remis, Perak have been banned from being consumed because of high levels of cadmium, nickel, lead and zinc.
Human and agricultural waste
In a number of cases where cockle culture beds are in vicinity of piggery waste discharges, (e.g. in Batu Maung, Penang) and human waste discharges (e.g. in Jelutong, Penang) the levels of faecal coliform have been found to exceed the permissible level for human consumption (200 FC-MPN/gm). In view of this, harvesting of existing cockles from the area has been stopped and future culture in the areas is disallowed by the Department of Fisheries.
5.2.3 Effect of cockle culture on the environment
The effect of cockle culture activities on the surrounding environment has not really been monitored, but it can be expected that some of the management activities, such as culling and harvesting of the cultured cockles, can bring about short-term physical disturbances of the immediate water habitat. This is especially true with the introduction of a mechanical harvesting “kor” into the cockle culling and harvesting techniques.
A study was carried out to see the effect of mechanical harvesting using the “kor” on the cockle culture bed at Kuala Juru in 1983 (Ng, 1984). The project included studies on the effect of kor use on the sea bottom-mud and benthic organisms, water quality, primary productivity, growth rate of cockle, size at first maturity. The results were inconclusive except that there were some indications that the gross primary productivity of the area increases for a period of time but settles back to normal after some time. Whenever the culture areas experience mass mortality (due to the extensive areas and hence the large biomass of dead cockles) the adjacent water and the coastal substratum quality in vicinity will be high in sulphide. This will have a significant impact on the existing local aquatic fauna.
5.2.4 Legal framework for the environmental management of aquaculture in relation to cockle culture
As has been mentioned, cockle culture is included in the Fisheries Act 1985 and Regulation 1986. The various conditions which the DGF may impose in issuing a permit for cockle on bottom culture are listed in Table 12. The conditions for a licence are the same as in Table 11. There are already existing laws and regulations in Malaysia but the issue here is how they will, firstly, be able to control and/or reduce the environmental impact on e.g, aquaculture ,and secondly, how they will have an effect on the cost effectiveness of the industry and the implications for the growth and development of aquaculture in the near future.
Section 8 of the Fisheries Acts states that no one is allowed to use mechanical means to harvest cockles. The definition of mechanical means is not clearly defined in this case. The apparatus used to harvest cockles has been modified from a hand held drag sieve to that which is attached to a long wooden pole and dragged from a mechanised boat.
Table 12. Conditions that the DGF may impose in issuing a permit for cockle bottom culture.
|Permit for on-bottom culture.||1. Use of structure and equipment.||1.||No change of structure without permission of DGF.|
|2. Location/site.||2.||No resisting or extension of location without permission of the DGF.|
|4. Pharmaceutical preparations.||4.|
|5. Records of aquaculture information.||5.|
|6. Disclosure of information.||6.||Disclosure of information on the operation upon request by any fisheries officer.|
6. PRIORITIES FOR DEALING WITH ENVIRONMENTAL ISSUES
There is a need for the nation's aquaculture industry to expand further in order to meet national objectives. At the same time, there is a need to minimise “negative” impacts on the surrounding environment. Research, which has devoted much of its attention so far to improving existing technology or developing new ones for increased production, needs to concentrate on environmental aspects so as to evaluate and reduce environmental impacts. There is a need to identify the environmental impacts which are of greatest concern and which may be reduced by good management, technical improvements or by careful planning (Pillay, 1992).
6.1 Prevention and cure of the detrimental effects to aquaculture of man-made changes to the environment
The Department of Fisheries, Malaysia, has carried out work on water quality monitoring and criteria for fisheries and aquaculture. The stringent regulations already established under the Environmental Quality Act and Regulations should be enforced on existing and planned and based industries in order that the water quality standards ascertained for aquaculture can be met. The Department of Fisheries has also initiated action to designate certain water bodies and coastal areas for fisheries and aquaculture use (Hanafi, 1991). Establishment of factories and other potentially polluting activities would not be allowed in these areas in order to minimise the impact of environmental degradation.
With the availability of GIS/ remote sensing technology at the Department of Fisheries, it is possible to develop zones which are historically free from red tide occurrence and also suitable for aquaculture. The tool would also be useful for its potential to monitor the development of, and the areas involved in any future algal blooms.
Contamination of aquaculture products
Constant monitoring of red tides and fisheries product quality should enable authorities to inform the public of the dangers of consuming certain products such as shellfish. This is an effective way of minimising potential human health risks. There has been growing consumer concern with regard to the level of sanitation of the main edible shellfish. Being a major aquaculture product in Malaysia, the government has taken measures to protect the cockle industry through advising farmers of suitable locations for culture and the development of technology for rendering cockles safe for human consumption through depuration.
6.2 Prevention and cure of the deterimental effects of environmental change caused by aquaculture activities
The following recommendations were made to limit the polluting and self-polluting effects of aquaculture activities:
In pond farms, frequent water changes should be made (or cleaning of the filters in continuous flow systems);
The use of paddle wheels or other devices is recommended in pond farms to increase oxygen levels;
Stock ponds with herbivorous fish to control algal blooms;
Educate farmers to be more discriminate in the use of antibiotics to prevent the development of resistant bacterial strains;
Regular screening against disease-infected stocks;
Proper monitoring of aquaculture development e.g. through licensing;
Developing alternative cage designs and management systems for the practice of open sea fish culture.
Measures are being taken by the Department of Fisheries to introduce culture techniques for both larval and growout operations without the use of chemotherapeutants. The National Prawn Fry Production and Research Centre, for example, has introduced larval rearing techniques using minimal amounts of antibiotics.
Impact of coastal aquaculture on mangroves
Certain guidelines, such as the use of mangroves for shrimp farms, have been established but are often not adhered to. Stricter enforcement of these measures is required. The Department of Fisheries also encourages the use of idle or unproductive and uneconomical agricultural land for the construction of fish/prawn ponds.
Interactions between aquaculture and native species
Stock enhancement programmes should be undertaken to replenish wild stocks of freshwater and marine fish. At the same there should be a detailed study of the effect of the restocking programme on the habitat particularly the ecological balance and species diversity of the existing gene pool.
7. FUTURE AQUACULTURE DEVELOPMENT
In summary, there is a need to develop aquaculture in Malaysia in order to reduce the high levels of exploitation and dependence on natural fisheries resources. This will provide the 250,000 tonnes of fish required by the year 1995 in Malaysia.
There has been a tremendous increase in the disposal of effluents and wastes into freshwater bodies and coastal waters due to the development of both land-based industries and aquaculture. There has also been a growing awareness of the importance and need to preserve the environment. These are constraining factors that can slow down the present growth of aquaculture in Malaysia. To ensure that progress and growth of the aquaculture industry will not be affected by: (i) the lack of available suitable sites for aquaculture; and (ii) controls intended to promote and protect the environment, it is important that the Malaysian government adopts various strategies to look into the matters.
These should include:
Implementing and enforcing the present regulations, to establish zonings for the various aquaculture activities as has been done for some states;
Adopting aquaculture systems and management techniques that are environmentally friendly and which will promote sustainable aquaculture development of natural resources;
Enhancing the use of biological techniques rather than chemicals in aquaculture.
There is a need for aquaculture to be recognised as an emerging sustainable industry of value to the community that is likely to increase in size and value with time. As such, the industry should seek that planning and regulatory processes promote -- not inhibit -- its future development. At the same time, the industry should develop and enforce its own code of practices for environmental protection and conflict amelioration and mitigation. Research in future should emphasise development of technologies that are environmentally friendly and that provide equitable social benefits. Sustainability should characterise every culture system that is developed.
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