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Brackishwater Aquaculture

The course will help the interested learners to start their own Brackish water Aquaculture ventures or cater as technical persons for managing the fish/shrimp farms.  

120 STUDENTS ENROLLED
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The course will help the interested learners to start their own Brackish water Aquaculture ventures or cater as technical persons for managing the fish/shrimp farms.  

Course Reviews

  1. BRACKISH WATER AQUA CULTURE
    1. INTRODUCTION

    The role of fisheries in Bangladesh in supplying animal protein, in providing employment, in earning foreign exchange and in supporting multifarious ancillary industries at the rural levels is well-known. The fishery-based economy will, no doubt, gain even greater importance in the future. Because of the limitations of capture fisheries and the vast potential for the development of culture fisheries, most of the additional fish production, necessary for domestic consumption or for export will have to come from aquaculture. It is also felt that a large part of the surplus labour could be productively absorbed through the development of aquaculture.

    In Bangladesh, both freshwater and brackishwater aquaculture are practiced. Culture of marine organisms in the marine environment is, however, yet to be introduced. The Bay of Bengal and the associated river mouths are characterized by strong waves, wide tidal and salinity fluctuations, frequent cyclones and tidal bores. The open beaches are strongly surf-bitten. The lack of lagoons, backwaters or other sheltered marine environments is apparently why mariculture has not taken off. Extensive areas in the coastal belt are, however, under brackishwater aquaculture, which is entirely shrimp-based.

    Shrimp was once much cheaper locally than fish and was not considered an attractive food item. In the early Seventies, however, Bangladesh entered the world export market for shrimp and since then this Crustacea has suddenly become a very high-priced commodity. Simultaneous with the public sector efforts to harvest marine shrimp by trawling, some farsighted entrepreneurs began to look at brackishwater aquafarming. Before long, aquaculture efforts proved more rewarding than marine capture. More and more areas were brought under brackishwater aquaculture and more and more people engaged themselves in shrimp farming. The increasing demand and steadily rising price of shrimp in the international market caused a Silent revolution in brackishwater aquafarming development. Once a casual activity of little economic significance, brackishwater aquafarming soon emerged as a multi-million taka farming industry in a few years.

    All these developments took place in the private sector with very little inputs from Government. It is only since 1980, the starting year of the Second Five-Year Plan, that the contribution of brackishwater aquafarming has been officially recognized. With favourable environmental conditions for brackishwater aquaculture and the existence of large areas with good potential for aquaculture, the Government has given high priority to brackishwater aqua farming because of the urgent needs of export and rural employment.

    2. CONTRIBUTIONS

    2.1 Culture area
    2.2 Aquaculture production and value
    2.3 Fisheries export
    2.4 Employment

    2.1 Culture area

    The total area currently under aquaculture is 292,378 ha of which 48 per cent, or 125,000 has, is under brackishwater aquaculture.

    2.2 Aquaculture production and value

    In 1993-94, the total fisheries production was 1.087 million t, of which 24.2 per cent, or 264,190 t, was of aquaculture origin. According to DOF statistics, brackishwater farms produced 39,477 t of shrimp and fish, of which shrimp accounted for about 25,000 mt (204 kg/ha) and fish about 14,000 mt.

    In the total aquaculture production, brackishwater farms contributed 15 per cent by weight and an estimated 38.5 per cent by value. The total cultured shrimp, brackishwater products accounted for 86 per cent by volume and 84 per cent by value. In all shrimp taken together (100,538 t), brackishwater farm-raised shrimp accounted for 25 per cent by weight and 50 per cent by value.

    2.3 Fisheries export

    In the total fisheries export of 31,835 t (valued at Tk. 9,210 million) in 1993-94, the shrimp component of the culture fisheries contributed approximately 52 per cent by volume and 64 per cent by value. Brackishwater aquaculture products contributed 86 per cent by volume and 84 per cent by value of the export originating from culture fisheries.

    2.4 Employment

    Estimates of employment in various farm-related activities are presented in Table 1.

    Table 1: Estimated employment in brackishwater aquaculture

    Activity

    Number of people engaged (in thousands)

    Men

    Women

    Total

    Fry collection

    99,000

    55,000

    154,000

    Fry trading & transportation

    1,500

    1,500

    Farming

    50,000

    50,000

    Shrimp depot workers

    400

    1,100

    1,500

    Shrimp van/boat operators

    1,500

    1,500

    Processing factory workers

    400

    1,100

    1,500

    TOTAL (appx.)

    152,000

    57,000

    210,000

    Source. Field data

    3. GEOGRAPHICAL DISTRIBUTION OF FARMS

    3.1 Culture waters
    3.2 Pond area

    3.1 Culture waters

    Brackishwater aquaculture is mostly practised in low-lying tidal flats within Bangladesh Water Development Board (BWDB) polders. The polders were originally constructed to prevent the land from brackishwater inundation and to enable the reclaimed land to be used for agriculture. In many places, the farmers themselves have constructed dykes along the river banks for the dual purposes of agriculture and aquaculture.

    Brackishwater aquaculture is practised mostly where the land is low and tidally inundated. Excavation of relatively high land to make its level lower and allow tidal inundation for aquaculture purposes is not common. Use of a pump to supply water from the surface or from underground layers to initially fill the ponds and subsequently replenish them is seen in exceptional areas in Kaliganj and Shyamnagar thanas and Satkhira district. These farms are completely pump-fed and are small, ranging from a fraction of a hectare to a few hectares in size.

    In Pirojpur, Patuakhali, Paikgacha and Rampur areas, many small domestic ponds are connected with tidal creeks. These ponds, originally meant for household washing, have, of late, begun to be used for brackishwater aquaculture of various degrees of intensity.

    3.2 Pond area

    A survey conducted by the Department of Fisheries revealed that in 1982-83 there were 51,835 ha of brackishwater ponds in Bangladesh. In 1984-85, the brackishwater farming area was estimated at 70,331 ha (Aquatic Farms Ltd, Hawaii USA, engaged by the Asian Development Bank). The brackishwater aquaculture area thereafter further expanded and reached 108,280 ha in 1988 (DOF estimated). The Department of Fisheries have been using this figure until 1994-95. But the first author (M Karim) of this paper made an estimate of the culture area in 1993 through DOF field officers and arrived at a figure of 125,235 ha (see Table 2).

    Table 2: Districtwise brackishwater aquaculture areas

    District

    1982-83

    1984-85

    1988-89

    1993-94

    Ha

    % of total

    Ha

    % of total

    Ha

    % of total

    Cox’s Bazar & Chittagong

    19,539

    37.7

    24,468

    30.5

    27,453

    27,385

    21.8

    Bagerhat

    11,013

    21,2

    22,158

    31.5

    79,728

    40,740

    32.5

    Khulna

    12,817

    24.7

    13,465

    19.1

    30,187

    24.1

    Satkhira

    8,001

    15.4

    13,240

    18.8

    23,924

    19.1

    Others

    465

    0.9

    1,099

    3,000

    2.4

    TOTAL

    51,835

    100.00

    70,331

    100.00

    108,280

    125,236

    100.00

    The DOF recently estimated the total shrimp culture area in 1993-94 as 138,000 ha. The figure does not separately indicate the brackishwater farming area. The Galda farming areas excluded, the brackishwater farming area would possibly be around 125,000 ha.

    4. CULTURE PONDS

    Brackishwater aquaculture in Bangladesh is generally carried out in large tidal ponds each of which actually consist of a large number of contiguous private plots owned by several people. An entrepreneur farmer can lease the land for various lengths of time but normally does not take it for more than three years at a time. The entrepreneurs then separate the leased areas by erecting a high boundary dyke enclosing the land. A pond thus created has its own water inlet and outlet, mostly of wood. Masonry sluices or reinforced cement concrete (RCC) pipes are also used. The water control structures are usually imperfectly constructed. No engineering devices, such as cut-out walls, are adopted to effectively prevent water leakage. The wooden sluices are usually made with unseasoned and untreated wood and, consequently, get deformed and leaky quickly. The dykes are normally low and often have holes in them that allow easy entry of pests animals into the pond. The ponds are shallow, generally not maintaining the required water depth of around 1 m. The pond bottoms are uneven, thereby hampering easy harvest of the cultured shrimp or removal of the pest animals.

    5. GENERAL CULTURE SYSTEM

    5.1 Culture system during the ’70s
    5.2 Culture improvement effort during the ’80s and ’90s

    Brackishwater aquaculture in Bangladesh is primarily shrimp-oriented. The target for culture is Bagda (black tiger shrimp), Penaeus monodon. The culture system is still rather unsophisticated.

    5.1 Culture system during the ’70s

    In the Seventies, when brackishwater aquaculture started as an important economic activity, the culture system was quite primitive. The ponds were large and ill-defined. Pre-stocking pond preparation techniques were not known. Farming almost entirely depended on the autostocking principle rather than on selective stocking with target species. Supplementary stocking with target species was the exception. Initial eradication and subsequent control of pest or competitor animals by poisoning or screening were not practised. Ponds were shallow and often infested with aquatic vegetation. Liming and fertilization techniques were not pursued. The need for stocking healthy fry and pre-stocking acclimatization of fry with pond water was not appreciated. The principles of water management to enhance and sustain the pond’s natural productivity were not known. The farming system was not based on science and production depended more on luck than on scientific principles.

    5.2 Culture improvement effort during the ’80s and ’90s

    From the early Eighties, the Government of Bangladesh has been endeavouring to improve on the traditional culture practices. The FAO/SIDA Bay of Bengal Programme, the First Aquaculture Development Project (ADB), the Shrimp Culture Project (IDA), the Second Aquaculture Development Project (ADB) and the Third Fisheries Project (World Bank) have all contributed to the national effort in improving on the traditional shrimp culture technology. Techniques that all these projects have tried to transfer to the farmer during the last several years include:

    – Nursery rearing of post-larvae;
    – Pre-stocking pond preparation by drying, pest eradication, liming and fertilization to stimulate production of natural food organisms in the pond;

    – Screening of the pond sluices with a fine-meshed synthetic screen to prevent or reduce intrusion of pest animals through incoming tides;

    – Selective stocking with Bagda (tiger shrimp) post-larvae;

    – Maintenance of around 1m depth of water;

    – Selection of healthy post-larvae and their acclimatization to the growout pond water before stocking;

    – Water management, to sustain adequate natural food production in the pond and to maintain appropriate levels of oxygen, pH temperature and salinity;

    – Regular sampling of water quality;

    – Recording of input supply information, shrimp growth data; production and sale proceeds data;

    – Post-harvest care; and

    – Analysis of data for future improvements of culture operations.

    The demonstration, extension and training activities under the projects have created interest and awareness about improved technology and management amongst the farmers. However, applications of improved techniques are still haphazard, imperfect or incomplete in most farms and not suitably adapted to the specific farm conditions. As a result, farm production levels have not improved much. The farmer’s incapability as well as the farm’s structural inadequacies both contribute to the low production.

    6. VARIOUS CULTURE PRACTICES IN USE

    6.1 Based on species mix
    6.2 Based on alternation of crops
    6.3 Based on seasonality of brackishwater
    6.4 Based on the fry stocking and harvesting system
    6.5 Based on water source
    6.6 Based on the fry stocking rate and the degree of management Three basic types of culture systems seem to exist:

    6.1 Based on species mix

    6.1.1 Mixed culture of Bagda with heterogeneous species
    6.1.2 Monoculture of Bagda

    6.1.1 Mixed culture of Bagda with heterogeneous species
    Screens are not used or are used only occasionally. In this type of culture, entry of non-predatory fish, e.g., mullets and such species of exportable shrimp as Penaeus indicus (white shrimp) and Metapenaeus monoceros (brown shrimp), is desired, but heterogeneous species of highly predatory fish and crabs also enter the pond freely. Bagda fry is stocked separately.

    6.1.2 Monoculture of Bagda
    In this type of family, culture of Bagda alone is intended. But a pure monoculture seldom exists because of the inevitable intrusion of pest animals because of imperfect screening. As a result, most monoculture farms are degraded and become mixed culture farms.

    6.2 Based on alternation of crops

    6.2.1 Bagda alternating with paddy
    6.2.2 Bagda alternating with salt

    6.2.1 Bagda alternating with paddy
    February-mid-August:

    Bagda (normally with heterogeneous shrimp and fish, which are either deliberately allowed entry or are intruders)

    Mid-August-December:

    Transplanted aman

    Rotation of aquaculture with agriculture is the most commonly practiced farming system in the brackishwater belt of the southwestern zone which covers the Bagerhat, Khulna and Satkhira Districts. During the high salinity period (February-July), marine and brackishwater shrimp and fish are cultured. During freshwater or the low salinity period (August-December) cultivation of a slat-resistant transplanted aman paddy is done in the elevated parts of the field. Simultaneous with the paddy, the leftover undergrown euryhaline shrimp and fish may continue to grow in the ditches of low-lying parts of the farm. Some farmers even combine freshwater shrimp (Macrobrachium rosenbergii) and fish, e.g., tilapia, carp, Thai sharpunti, etc., with the euryhaline species.

    Seasonal shrimp culture in rotation with paddy in the same field is an excellent example of integrated farming practice in which aquaculture and agriculture support each other rather than compete against each other. The shrimp excreta, cast-off shells, leftover feed and the residual fertilizers all add to the fertility of the soil and improve paddy production. On the other hand, stumps of harvested paddy and the ploughing of the soil help increase productivity of the water and, hence, production of shrimp. However, prolonging the brackishwater aquaculture process and occupying land beyond the optimum period for paddy transplantation often creates serious conflicts between the aquafarmers and agricultural farmers. Such conflicts are unfortunate, but certainly avoidable. Crop rotation is not only good for both crops, but also helps sustain productivity of the soil.

    6.2.2 Bagda alternating with salt
    December-April:

    Salt

    May-November:

    Bagda (normally with intruder species)

    In the eastern zone, where the salinity level in general is much higher than in the western zone, shrimp culture and salt production in rotation is the usual practice. Shrimp is cultured during the wet season, mid-May to mid-October, while salt is produced during the dry and high saline period of December-April.

    6.3 Based on seasonality of brackishwater

    6.3.1 Seasonal culture
    6.3.2 Perennial culture

    6.3.1 Seasonal culture
    February-mid-August:

    Most areas in the Khulna region and many places in Cox’s Bazar region.

    May-November:

    In salt production areas in Chakoria, Maheshkhali and Teknaf.

    6.3.2 Perennial culture
    In a few areas, where river salinity is suitably high the year round, shrimp is cultured almost perennially. Such farms are found in Syamnagar, Koira and Assuni thanas in the southwestern zone and Taknaf, Maheshkhali and Cox’s Bazar thanas in the southeastern zone.

    6.4 Based on the fry stocking and harvesting system

    6.4.1 Continuous stocking and continuous harvesting
    6.4.2 One-time stocking and periodic harvesting

    6.4.1 Continuous stocking and continuous harvesting
    Be it seasonal culture or be it perennial culture, this involves one-time pond preparation in the beginning and one-time complete harvesting at the end. During the whole culture period, multiple stocking and harvesting are done. This is the usual practice amongst the farmers.

    6.4.2 One-time stocking and periodic harvesting
    In this case, there is one-time stocking in the beginning, periodic harvesting during the culture season and complete harvesting at the end of culture. A new culture cycle is restarted every 4-5 months after pond drying, liming and fertilization in double crop areas where suitable salinity is available for at least eight months. This type of culture is ideal, but most farmers do not practise it.

    6.5 Based on water source

    6.5.1 Completely tide-dependent
    6.5.2 Completely pump-dependent

    6.5.1 Completely tide-dependent
    This is by far the most common culture practice. However, tidal inundation in the greater part of the farming area in February, which marks the beginning of culture season, is quite inadequate. The land is relatively high compared to the tidal height. Most of the farming areas in Bagerhat District, nearly three-fourths of the area in Cox’s Bazar District, and more than 50 per cent of the area in the Khulna and Satkhira Districts cannot be tidally inundated under even 50 cm of water at the beginning of the culture season. Yet, the farms depend upon tide alone. Chakoria and Rampal are the two thanas which have the largest areas of Bagda farms, but they are amongst the worst from the point of view of tidal inundation. Supplemental pumping could significantly increase productivity here, but it is not used.

    6.5.2 Completely pump-dependent
    Several hundred ponds in the Kaliganj and Shyamnagar thanas of Satkhira District are located at rather high levels and are not inundated by tide at all. These farms depend completely on pumped water, mostly low-lift but some are shallow.

    6.6 Based on the fry stocking rate and the degree of management Three basic types of culture systems seem to exist:

    6.6.1 Extensive type
    6.6.2 Imperfectly improved extensive type
    6.6.3 Semi-intensive/intensive culture

    i) The extensive type;
    ii) The improved extensive type; and
    iii) The semi-intensive/intensive type.
    The salient features of the three types of culture are summarized in Table 3.

    Table 3: Selected features of three existing culture types

    Culture type

    Artificial stock of Bagda per m²

    Liming and fertilization

    Artificial feeding

    Screening

    Aerator

    Pumping

    Shrimp production kg/ha/year

    Extensive

    1-1.5

    No

    No

    No or very imperfect

    No

    No, tide-fed

    150-200

    Imperfectly Improved extensive

    1.5-3.0

    Yes

    No/Yes

    Yes, but not perfect

    No

    No, or completely pump-fed

    250-750

    Semi-intensive/ Intensive

    20-40

    Yes

    Yes

    Yes and much better than in improved extensive

    Yes Partly tide-fed and partly pump-fed

    3000-6000

    6.6.1 Extensive type
    This is the predominant culture type currently in practice. An estimated 75 per cent, or over 93,000 ha, of the brackishwater culture area (125,000 ha) is under extensive culture. The average production of shrimp is possibly 175 kg/ha.

    6.6.2 Imperfectly improved extensive type
    An approximate 25 per cent or 28,000 ha, of the culture area is under what can be called imperfectly improved extensive type of culture or is in a transitional state between extensive and improved extensive type. The shrimp production possibly averages 300 kg/ha.

    6.6.3 Semi-intensive/intensive culture
    ‘Semi-intensive shrimp culture’ is a term for which an internationally, regionally or locally acceptable definition is not available. In Bangladesh, the term is very loosely used, assigning no upper limit to the stocking rate. The culture system as it is being practised at present, consists basically of high stocking rates (25-60 m2), heavy artificial feeding, pumping of water and using aerators. The so-called semi-intensive culture (which is actually intensive) sporadically demonstrated impressive production results exceeding 5t/ha in 4-5 months in 1993. The high production rates, although achieved only in a few farms for one season, generated a great deal of enthusiasm amongst the entrepreneurs and many financial institutions. In 1994, 36 farms, covering an estimated are of 700 ha in the Cox’s Bazar District, started semi-intensive shrimp culture. But the shrimp in most of the farms suffered mass mortality due to diseases. A similar disaster recurred in 1995 also.

    That unplanned and uncontrolled high intensity shrimp culture practices, as started by many private farmers in 1993, could lead to outbreak of shrimp diseases, mass mortality and environmental pollution had been earlier predicted by some local experts. The Ministry of Fisheries and Livestock, referring to the expert opinions and to the experience of Taiwan, the Philippines, China, Thailand and some other countries, cautioned all concerned against the possible hazards of high-intensity shrimp culture.

    7. CRITERIA FOR APPROPRIATE FARMING TECHNOLOGY

    In view of the country’s depressed socioeconomic status, low technological base, private ownership of most of the suitable land, short-term leasing systems, lack of infrastructure, diversified environment in terms of land elevation, tidal inundation and hydrological characteristics, a production technology can be called appropriate only if it satisfies all or most of the following criteria:

    – Requires low capital;
    – Can be applied to land taken on short- and medium-term lease;

    – General farmers can easily adopt with short-term training;

    – Can be applied in existing farms without substantial topographic changes;

    – Production is much higher with relatively low financial risk, compared to the traditional methods;

    – Little or no dependence on imported machinery and raw materials;

    – Little or no dependence on machinery that require electricity supply (which is not available in most of the coastal areas or, where available, is seldom stable and dependable);

    – Can create new employment opportunities;

    – Can benefit all or most of the farmers in an ecological area for which the technology is intended;

    – Does not pollute, upset or degrade the ecosystem or cause diseases (Bangladesh shrimp is still disease-free and of pollution free origin. The shrimp is raised completely on natural food rather than artificial products and no antibiotics or any prophylactic chemicals are used in the farms. As a result, the Bangladeshi shrimp enjoys an advantage in the international market.);

    – The farming system can be sustained on a profitable basis year after year; and

    – Keep production cost low, thus allowing easy survival of the product in the competitive international market. (Bangladesh can more effectively attract a foreign market by offering a lower price than by attractive presentation of its products).

    A culture technology, should not be recommended, however high its production potential is, if it cannot be sustained on a long-term economic basis and if it creates a clearly adverse impact on the environment.

    8. RECOMMENDED FARMING SYSTEMS

    8.1 Monocrop Bagda area: Bagda alternated with paddy
    8.2 Monocrop Bagda area: Bagda alternated with salt
    8.3. Double crop area: Two Bagda crops

    Having considered the criteria given above to determine culture technologies appropriate for Bangladesh, the authors recommend the following diversified culture technologies for marine shrimp, for farms of different environmental qualities and farmers of different financial and technical backgrounds.

    8.1 Monocrop Bagda area: Bagda alternated with paddy

    Within the suitable shrimp culture area, land in which soil and water salinities remain below 3 ppt continuously for at least four months, thereby allowing paddy production, should be utilized for improved extensive culture of tiger shrimp’ alternating with salt-resistant transplanted aman, the latter could be simultaneously grown with euryhaline fish, galda, tilapia, carp sharpunti, etc.

    Tiger shrimp:

    February-end July/mid August

    Paddy:

    August-December

    The culture techniques for Bagda shrimp are summarized below:

    MONO CROP BAGDA AREA: Shrimp alternated with paddy ALL IMPROVED EXTENSIVE, NO SEMI-INTENSIVE CULTURE

    i) Ponds having adequate tidal inundation, manuring and fertilization

    No feed:

    250-400 kg/ha

    Suppl. feed:

    400-600 kg/ha

    Supp. feed + pump as needed:

    500-800 kg/ha

    ii) Ponds with inadequate tidal inundation, tide + pump, manuring and fertilization

    No feed:

    300-500 kg/ha

    Suppl. feed:

    500-800 kg/ha

    iii) Ponds not tidally inundated at all, completely pump-fed, manuring and fertilization

    Suppl. feed:

    600-800 kg/ha

    ¹NOTE: For tiger shrimp culture, only those areas where river water or underground water salinity remains at or above 8 ppt continuously for at least four months are considered suitable.

    8.2 Monocrop Bagda area: Bagda alternated with salt

    In many parts of the Cox’s Bazar area, salinity of water is too high (above 25 ppt.) to permit Bagda culture or the tidal height is too low to adequately inundate the pond during the dry season (December-April). In these places, salt should be produced during the dry season and Bagda during the wet season (May-November).

    Tiger shrimp:

    May-November

    Salt:

    December-April

    The culture techniques for Bagda shrimp are summarized below.

    MONO CROP BAGDA AREA: Shrimp alternated with salt ALL IMPROVED EXTENSIVE, NO SEMI-INTENSIVE CULTURE

    i) Ponds having adequate tidal inundation, manuring and fertilization

    No feed:

    250-400 kg/ha

    Suppl. feed:

    400-600 kg/ha

    Supp. feed + pump as needed:

    500-800 kg/ha

    ii) Ponds with inadequate tidal inundation tide + pump, manuring and fertilization

    No feed:

    300-500 kg/ha

    Suppl.

    feed: 500-800 kg/ha

    8.3. Double crop area: Two Bagda crops

    Within suitable shrimp culture areas, land where paddy cultivation is not feasible even in the wet season, because of prohibitive levels of soil salinity (above 3 ppt.) and water salinity remaining at or above 8 ppt for eight months or longer, the following culture modules for two crops of Bagda could be demonstrated and introduced. Improved extensive type would be the general farming system, but the “semi-intensive system on a limited scale could also be tried in selected areas when sufficient fry and sufficient suitable feed could be locally produced in hatcheries and feed mills to meet the additional demand.

    DOUBLE CROP BAGDA AREA: Two Bagda crops IMPROVED EXTENSIVE

    Ponds having adequate tidal inundation, ponds completely tide-fed, manuring and fertilization

    No feed:

    450-550 kg/ha (250-300 kg) + (250)

    Suppl. feed:

    500-800 kg/ha (250-500) + (250-300)

    Suppl. feed + pump as need:

    600-1000 kg/ha (350-600)+(250-400)

    Tide + pump, manuring and fertilization

    No Feed:

    450-650 kg/ha (250-400)+(200-250)

    Suppl. Feed:

    500-900 kg/ha (250+600)+(250+300)

    SEMI-INTENSIVE

    Tide + pump + aerators

    Feed:

    Stocking 7-15/m2

    Production:

    2,300-4,500 kg/ha (1300-2500)+(1000-2000)

    9. SOME SELECTED ISSUES AND RECOMMENDATIONS

    9.1 Low production rates, reasons and recommendations
    9.2 Land-use conflicts, and policy
    9.3 Dearth of culturable shrimp fry
    9.4 Artificially formulated feed
    9.5 Other recommendations

    9.1 Low production rates, reasons and recommendations

    9.1.1 Reasons
    9.1.2 Recommendations

    9.1.1 Reasons
    Much of the extension efforts for improving on the traditional culture system has been wasted because the recommended culture techniques could not be appropriately applied in most of the existing farms. The reasons for this are:

    – Ponds are generally unmanageably large and have irregular shapes, uneven bottoms, shallow depths, inadequate and leaky sluices and inadequate water supply and drainage networks.
    – Ponds are mostly in land taken on short-term (1-3 years in most cases) lease; the lessees are, therefore, not permitted by the owners to excavate the land for construction of canals for water distribution, or build higher peripheral dykes, to hold the appropriate depth of water, and partition dykes, to reduce pond size into easily manageable units. Now the ponds are, therefore, exceedingly large and have shallow water depths, hardly exceeding 45 cm as against the required 1m depth.

    – Because of their very large sizes and shallow depths, enhancement of productivity of such ponds by pest control, fertilization, feeding, water exchange or any other improved management techniques is very difficult.

    9.1.2 Recommendations
    Culture infrastructure development

    One or the other of the following options could be adopted:

    i) The land owners of each area should form one or more association (s) and develop the ponds as an integrated complex with common water supply and drainage canals. Each pond owner, however, should undertake shrimp culture in his pond.
    ii) Alternatively, the land owners may decide to sell their land to other farmers or lease it out on a long-term basis, with permission to the lessees to bring about the structural changes required to undertake semi-intensive shrimp culture. In this case also, an integrated development approach will be required to ensure appropriate utilization of the entire area.

    iii) As a third alternative Government should provide polder-specific total development plans and create a basic supply and drainage network (gravity flow or pump lifting) on either side of selected rivers. This will encourage farmers to undertake further development and improvements on their own. For example:

    – Construction of a large number of suitably designed ponds with improved water supply and drainage systems.
    – Reduction of large ponds into easily manageable small units. For improved extensive type of farming, 1-5 ha unit should be suitable. The size should not exceed 10 ha.

    – Utilization of a much greater proportion of the land located in areas suitable for shrimp culture.

    iv) As a fourth alternative, the Government may do the necessary development work either on khas land or acquired land and allot the ponds to interested individual farmers or their associations on appropriate terms, more or less on the principle adopted by RAJUK or private housing estates for house construction.

    9.2 Land-use conflicts, and policy

    9.2.1 Need for policy
    9.2.2 Policy recommendations Land classification

    9.2.1 Need for policy
    Conflicts on the use of coastal land for paddy, shrimp, salt and mangrove plantation, cattle grazing, etc. exist and often lead to social and technical problems. Most of the problems could be avoided if there were a policy for land use.

    9.2.2 Policy recommendations Land classification
    Based on land topography, tidal inundation, water salinity, soil quality and other environmental factors and relative economic return, a land utilization policy should be urgently formulated. Land should be classified and assigned to one or a few specific use’s, for which the land is technically most suitable and economically most profitable.

    Earmarking land for brackishwater and freshwater shrimp

    – The coastal area where river water salinity remains at or above 8 ppt. for at least four months of the year should be declared as brackishwater aquaculture area.
    – Land within the declared brackishwater aquaculture area, where river salinity remains at or above 8 ppt. for at least 8-9 months of the year, should be primarily utilized for brackishwater aquaculture, with shrimp as the major culture species. Other farming activities, if any will have to be adjusted to shrimp farming.

    – Land where soil and river water salinity remain below 3 ppt. for four months or more, can be utilized for both paddy and shrimp in rotation: paddy during the low saline months and shrimp during the high saline period. The land must be freed for paddy production by August 30th.

    – Land where soil salinity is always over 3 ppt. and river water salinity over 25 ppt. for a few months during the dry months could be used for brackishwater aquaculture alternated with salt production: salt during dry months and aquaculture during wet months.

    – Monsoon-flooded or tidally-flooded low-lying freshwater or slightly brackishwater upto 7 ppt. areas close to a natural source of wild seed or to a hatchery should be considered on a priority basis for M. rosenbergii and fish polyculture. Suitable culture areas located far from seed sources may be taken up later as hatchery techniques develop on a commercial basis.

    9.2.2.2 EARMARKING GOAT AND CATTLE GRAZING LAND

    Within both high and low saline areas, some high land should be specifically earmarked for growing green fodder for livestock. The owners of the land should be appropriately compensated by the shrimp farms.

    9.2.2.3 EARMARKING LAND FOR MANGROVE PLANTATIONS

    9.2.2.4 SELF-FARMING OR LAND LEASING

    Formulation of policy for private shrimp land utilization is needed to encourage landowners to culture shrimp directly, either individually or in groups, or lease out their land on a long-term basis and allow the lease-holders to suitably alter topography of the land, by way of raising dykes, excavating canals etc., to enable adoption of improved culture technology. The and should not be allowed to keep any culturable land unutilized or underutilized.

    9.3 Dearth of culturable shrimp fry

    9.3.1 Present status
    9.3.2 Recommendations

    The most frequently encountered complaint from the shrimp farmers is the dearth of Bagda fry.

    9.3.1 Present status
    Both Bagda shrimp fry and Galda shrimp fry prices shot up 50-100 per cent in 1994 compared to 1993. In 1995 Bagda fry price went further up, exceeding Tk 3000 per thousand in the Khulna region. Both price hikes and the abnormal scarcity of Bagda fry adversely affected shrimp culture in 1994 and 1995.

    Taking advantage of scarcity and the resultant high price of shrimp fry, some people imported millions of fry from Thailand, Taiwan and Indonesia where shrimp diseases and mass mortalities of cultured shrimp have been a recurrent feature for the last several years. The situation has given rise to strong criticism and deep concern amongst shrimp farmers and environmentalists. Large-scale disease and mass mortality of shrimp in the intensive and semi-intensive farms in Cox’s Bazar have aggravated the concern.

    Despite the scarcity and high prices, there are colossal wastage of the fry. A close analysis of the issue indicates the following:

    – The existing Bagda farms(125,000-135,000 ha) stock an estimated 2,600 million post-larvae (at 20,000/ha).
    – The farm-raised Bagda shrimp production (17,500 t) represents an estimated 20 per cent survival (525 million shrimp of average weight 30 g) of the stocked post-larvae, revealing huge post-stocking wastage.

    – The stocked quantity of post-larvae represents a possible two-thirds of the quantity of P. monodon fry actually caught from Nature; the other third (1.3 billion) die due to handling and transportation mortality.

    – The cultured Bagda accounts for an estimated 13.5 per cent of the total Bagda fry caught (3,900 million).

    – Nearly 200 Bagda hatcheries would be required to produce the number of fry that are caught from the wild.

    As of now, Bangladesh depends almost entirely on Nature for culturable shrimp seed supply. The country’s most efficient operational tiger shrimp hatchery at Cox’s Bazar produces about 20 million post-larvae. Some sites have been earmarked by the Government for establishing tiger shrimp hatcheries, but they are all in the southeastern zone. The southwestern belt, where 75 per cent of the marine shrimp farms are located, does not have suitable environmental conditions for tiger shrimp hatcheries. There are a few Macrobrachium hatcheries which produce only a few million post-larvae.

    9.3.2 Recommendations
    Stop wastage of wild fry resources

    In view of the environmental limitations affecting marine shrimp hatcheries, appropriate measures should be immediately taken to stop wastage of the valuable natural resources which Bangladesh is getting absolutely free from Nature. The following measures are recommended:

    – Organized surveys of the Bagda post-larvae in the lower reaches of all the southern rivers, to assess the true magnitude of natural fry resources.
    – Scientific collection of Bagda fry from the lower reaches of the southern rivers and from the sea surf avoiding, or substantially reducing, wastage of non-target aquatic organisms.

    – Transportation of the fry from the catching areas to the fry-marketing and farming areas using modern technologies.

    – Pre-stocking acclimatization of the fry with the culture pond water.

    – Stocking of fry in the pest-free and well-prepared ponds.

    Promote establishment of Bagda shrimp hatcheries in the private sector.

    Five areas have been identified in Cox’s Bazar District for the establishment Bagda shrimp hatcheries all in the western part of Teknaf and Ukhiya thanas, bordering the Bay of Bengal. The five areas are located along a 40 km stretch and have an approximate total area of 105 ha and a combined sea frontage of 9 km. However, final selection of the site is subject to availability of adequate freshwater and consideration of its secured elevation above tidal bores. The recommended areas are in addition to an already declared hatchery zone in Kalatoli. The site should be further investigated and what is judged suitable land should be allocated to genuinely deserving candidates at the earliest. The Government would have to establish essential common infrastructure facilities in the areas. Investigations should also be made on the feasibility of establishing floating hatcheries or closed system hatcheries for Bagda shrimp in the Khulna region.

    Promote various feasible modules of Macrobrachium hatcheries.

    These should include:

    – An open water system using surface water or underground water. A survey of suitable underground saline water should be undertaken expeditiously.
    – A closed (recycling) system using brine water transported from salt beds.

    – Open and closed systems combined, in areas where river water salinity remains suitable for only a few months.

    Establish a modern system for fry transportation from the hatcheries to the farming areas and/or to the nursery areas.

    Develop large-scale nursery systems to hold Bagda shrimp and Galda fry through the winter months (September to January) for stocking in growout ponds in early February. This should be done in order:

    – to utilize the off-season cheap fry of Bagda and Galda,
    – to start Galda culture as early as February, rather than in July, in ponds having a perennial water source, and

    – to raise a full crop of tiger shrimp before the onset of the monsoon, which sometimes starts as early as May. A drastic drop in river salinity, due to heavy freshwater run-off, is rather common in the Chakoria area.

    Conserve shrimp broodstocks

    – Ban use of behundi nets in the entire stretches of the selected rivers from the estuarine zone down to the sea in order to encourage unhindered seaward breeding migration of the pre-adult shrimp during June-August. The would-be brood shrimp are most undesirably removed by hundreds of behundi nets set in the estuarine rivers.
    – Ban off-shore shrimping for a month during the peak tiger shrimp breeding season.

    Conserve and propagate mangrove cover

    Any further destruction of mangrove forests or bushes, either natural or planted, for expansion of. shrimp farming or for any other purpose, should be completely banned with immediate effect in order to:

    – Conserve the primary sources of nutrients for all the aquatic organisms in the estuarine environment;
    – Conserve the nursery and shelter grounds for the multitudes of shrimp and fish fry, including those of the tiger shrimp; and

    – Reduce erosion of the river banks and keep the silt load low in the rivers.

    The Sundarbans forests, already degraded or depleted by human interferences or otherwise, must be appropriately replenished and improved at the earliest.

    All the estuarine river banks, outside the shrimp farms, must be compulsorily afforested by the farm owners with appropriate mangrove species. The Forest Department should supply the seedlings against payment and also provide technical advice to the shrimp farm owners on mangrove plantation and maintenance. Wherever feasible, suitable trees (e.g.. Eucalyptus, ipil ipil, coconut, casuarina, acacia, etc.) should be planted on the dykes.

    9.4 Artificially formulated feed

    9.4.1 Present status
    9.4.2 Recommendations

    9.4.1 Present status
    In order to intensify shrimp culture beyond 400-500 kg/ha/crop, artificial feeding may be necessary. There exists only one operational feed mill – at Valuka, Mymensingh. Apart from its products, a few other feeds of local origin and under various brand names are available.

    Some of the essential feed ingredients, e.g., fishmeal, vitamin-mineral pre-mix, binder, etc., are in short supply. Some people import finished feed from Thailand and Taiwan. Storage facilities for feed at the field level are very poor. Shelf-life of feed even under good storage condition is about three months only. The farmers often offer rancid feed to the farm, creating health problems for the farm animals.

    9.4.2 Recommendations
    Formulated shrimp feed of various pellet sizes should be manufactured within the country. Feed adequate for 25,000 ha of improved extensive farming of Bagda shrimp (1000 kg/ha) and 500 ha of semi-intensive farming (3000 kg/ha) and 10,000 ha of Galda farming (1000 kg/ha) should be locally produced on a priority basis. The feed must be of international quality.

    – Local feed ingredients should be utilized as far as possible;
    – Export of ricebran, wheatbran, oil cake should be banned in view of the fact that these are essential components of cattle, poultry, fish and shrimp feed;

    – Any shortfall in fishmeal and vitamin-mineral pre-mixes, food-binder, etc, should be imported;

    – The feed manufacturers will have to ensure appropriate storage arrangements at the field level;

    – Regular quality monitoring of the feed stored at various levels should be introduced;

    – Heavy import duties should be levied on imported finished feed, while imports of essential raw materials not available locally should be duty- and tax-exempted in order to encourage establishment of local industries.

    9.5 Other recommendations

    9.5.1 Cautious approach to semi-intensive shrimp culture
    9.5.2 Pilot-scale operation before commercial operation
    9.5.3 Extension units
    9.5.4 Research support
    9.5.5 Infrastructure in shrimp farming areas
    9.5.6 Incentives

    9.5.1 Cautious approach to semi-intensive shrimp culture
    Defining intensity of ‘semi-intensive shrimp culture’

    The Ministry of Fisheries and Livestock has restricted the stocking rate at 7-15/m2 for semi-intensive culture. We support the rate and strongly remind farmers not to exceed the upper limit. At this stocking rate, the production could be 1400-2300 kg/ha/crop: this is high enough.

    Careful site selection

    Semi-intensive shrimp culture would be justified only in carefully selected, perennially saline areas where two Bagda crops could be raised and the risk of environmental pollution is minimal. Report on the Site Selection of Bagda Shrimp Hatchery Zones and Semi-intensive Bagda Shrimp Farming Areas, released by the Ministry of Fisheries and Livestock in August, 1994, is a useful guide for selecting suitable sites for semi-intensive marine shrimp culture.

    Appropriate time for expansion

    Bangladesh is not immediately prepared for semi-intensive shrimp culture on any appreciable scale, even at the recommended lower stocking rates. Semi-intensive culture efforts should not be taken up in isolation without first ensuring steady supplies of seed and feed of local origin, trained manpower and infrastructure.

    Engineering design

    The existing semi-intensive farm should have an adequate reservoir to stabilize the supply water quality before the water is introduced into the culture ponds. The farm should also have built-in facilities for treatment, disinfection and dumping pond sludge. Pond sludge must not be thrown into the river. Water from a diseased pond should be appropriately treated in a treatment pond before being released into the open water system.

    Experimental-cum-demonstration

    Two experimental model farm complexes, each of about 25 ha, could be established, one in Teknaf and one in Shyamnagar, as joint ventures of the public sector and carefully selected private farmers.

    9.5.2 Pilot-scale operation before commercial operation
    Large-scale application of any engineering design or new farming technology must be preceded by careful testing on a pilot scale of the proposed development model. Appropriately adjusted or improved as needed, the model can later be replicated on a large-scale with confidence.

    9.5.3 Extension units
    The farming area should be divided into several representative extension units, based on tidal inundation, water salinity, type of water supply (tide-fed or pump-fed), soil quality, farm type, etc. At a convenient point of each unit, a private farm should be used for a few consecutive years to demonstrate improved culture techniques, suitable under the local environmental conditions. Each unit should have at least one of such demonstration farm, which must play an effective role in extending improved cultural practices to the neighbouring farms.

    9.5.4 Research support
    The FRI’s brackishwater aquaculture research programme must be chalked out in close collaboration with the shrimp culture demonstration unit officers and the farmers. The technical problems already identified by DOF field officers and the farmers themselves must be addressed with utmost priority.

    In the case of M. rosenbergii, the hatchery operator can handle broodstock collection/development and nursery rearing along with hatchery operation because of the simplicity of techniques involved in the various activities.

    9.5.5 Infrastructure in shrimp farming areas
    Government should urgently establish essential infrastructure facilities, e.g., roads and waterways, power supply and telephone connections in the shrimp farming areas.

    Improved transportation systems will help maintain the shrimp quality, besides ensuring construction materials and production inputs, et.g., seed, feed, fertilizer, pumps, etc. can be transported quickly. Power supply will encourage private entrepreneurs to establish much-needed ice plants in remote areas and inspire farmers to use pumps. Electricity will also contribute to the security of the farm property and shrimp stocks.

    9.5.6 Incentives
    To farmers:.

    – Shrimp farming should be considered as an export-oriented industry and producers should receive various investment incentives, similar to shrimp trawler operators and shrimp processors and exporters.
    – Any perennial shrimp farm producing at least 1000 kg of P. monodon or other marine shrimp of not less than 30 g average size per hectare per year should be given special financial concessions and a certificate of honour. Any seasonal shrimp farm producing 500 kg/ha/yr of P. monodon or other penaeid shrimp of the above mentioned counts should also enjoy the above privileges.

    – Duty-free import of farm equipment, feed and other materials should be allowed and Government should ensure that the benefits of these concessions reach the general farmers.

    To extension officers:

    The DOF officer directly associated with the best demonstration and extension results or activity under each district should be awarded a Certificate of Merit and a cash incentive for meritorious work each year. The Government should have a system of annually selecting the officers directly connected with the best demonstration and extension work in each shrimp district.

    10. PLACE OF SMALL-SCALE SHRIMP FARMERS

    In Bangladesh, influential and rich farmers take on lease a large number of plots from landowners, many of whom are small farmers. The small farmers are often forced to lease out their lands to the big farmers. Data available from the Department of Fisheries suggest that the average size of existing farms is 15 ha, but farms well over 200 ha also exist. The ponds are exceedingly large compared to those common in Thailand, Indonesia, Taiwan, etc., where ponds over 5 ha are rare.

    Although the big farmers deserve appreciation for developing a new export-oriented industry and bringing it to the present scale, the current ownership pattern should not go unchecked in the greater interest of society. Increased poverty, landlessness and the likely social unrest warrant changes in the farming system. The socioeconomic factors inhibiting direct participation of the small and marginal landowners in profitable shrimp farming practices should be immediately looked into and a practical solution to the problem aimed at.

    Can small or marginal landowners pursue shrimp farming individually? Developing individual farms by erecting earthen dykes around a large number of small and scattered individual plots may not be technically feasible in most cases as the structures are likely to undesirably interfere with the water circulation within the gher. This leads us to wonder whether small landowners and big landowners can jointly farm in a cohesive group or as a cooperative and share the costs and profits of farming.

    The big landowners (lease-holders) are unlikely to take the initiative in this regard, but even if they do, the small landowners generally will not feel confident of establishing joint venture with a much more powerful counterpart. The Thana Shrimp Culture Regulation Committee is authorized by the Government to help and assist the marginal and small landowners to form co-operatives to undertake shrimp farming by them. But, to date, a genuine co-operative farm has not been reported as surviving for long.

    Whatever be the reasons of failure for not developing a co-operative/group farming system in the past, a concerned society cannot remain a silent observer to such a social issue. If something concrete is not done soon, many of the small or marginal landowners will soon degenerate into landless people with no definite source of income or employment. Group farming or co-operative farming, despite its past failures, is very likely the best approach to try afresh with new strategies. With Government backing, through adequate bank loans, legal rights, technical and management training, and State patronage, a viable group/co-operative farming system may gradually develop. An attempt could be made along these lines in a few selected ghers.

    Apart from the above institutional approach, a new technology could possibly be tried to benefit the small landowners. Penculture appears to be a prospective technology, allowing farming in a gher on an individual as well as group basis. An individual small farmer could enclose his plot with suitable netting material without interfering with water circulation in the gher. The holders of a number of contiguous plots could instal their pens side by side so that costs on common walls could be obviated. Instead of very small individual pens, several neighbouring farmers could jointly put up a large pen enclosing their plots, this could be a further cost-saving.

    However, penculture in a gher is only a concept; it has not been tried anywhere so far. Before demonstrating its techno-socioeconomic viability on experimental pilot scale, the technology should not be recommended for general use.

    Promotion of small-scale farming to benefit the small and marginal farmers is, ironically, a very big task, a task which the society cannot and should not evade any longer in its own interest. ‘Small is beautiful’. Let our efforts be to establish it.

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  2. Brackish water fish farming is a system of aquaculture
    that focuses on the production of quality fin and shell fish
    that are found in the creeks, lagoons, and estuaries through
    rational rearing. It has a capacity of bridging through
    wide gap between fish demand and supply.
    Aquaculture has been defined by the Japanese Resource Council, Science and Technology Agency as under:

    “Aquaculture is an industrial process of raising aquatic organisms up to final commercial production within properly partitioned aquatic areas, controlling the environmental factors and administering the life history of the organism positively and it has to be considered as an independent industry from the fisheries hitherto.”

    Aquaculture is organised production of a crop in the aquatic medium. The crop may be that of an animal or a plant. Naturally, the organism cultured has to be ordained by nature as aquatic.
    Examples are:
    Fin fish: Tilapia, carp, trout, milkfish, bait minnow, yellow tail, mullet, cat fish.
    Shellfish: Shrimps, prawns, oysters, mussels, pearl oyster for cultured pearls
    Cultivable brackish water shell fishes include shrimps and brachyuran mud crabs. According to FAO, there are over 300 shrimp species are available throughout the world.Only few species are commercially important either in capture fisheries or in the aquaculture industry. Among the 700 marine crabs of India, only two species of mud crabs are commercially cultured in brackish water ponds.
    Cultured shrimps and live mud crabs are the main shell fish commodity in export market.
    Biology of commercially important Penaeid shrimps distribution: Pcnaeid shrimps are widely distributed in Indo-west pacific water bodies. They are mainly cultured in coastal and off shore waters of both eastern and western hemisphere.
    Habitat: Adults penaeid shrimps generally found in off’ shore waters and spwan in the salinity regime of 30-35 part per thousand (ppt) at a depth of 30-100m. Juveniles often prefer brackish waters of estuaries and coastal wetlands, while larval stages inhabit plankton-rich surface waters off-shore, with an on-shore migration as growth advances.
    Life cycle : The penaeid life cycle includes several distinct stages and they are generally found in a variety of habitats. Adults migrate to the sea for breeding, during spawning. Eggs and sperm are simultaneously released from the female. Fertilization is external, and egg development occurs in the water column. The fertilized eggs are demersal and hatch within 14 hours to strongly phototropic nauplii (6 sub stages, each moult every 4-6 hr interval), which swim towards the surface after 36 hr.
    Food and feeding habits: Penaeid shrimp are known to ingest a variety of items and have been described as omnivorous, detritus feeders and carnivores. Their diet ranges from the hereditary yolk sack, during the early naupliar stage to phytoplankton at protozoeal stage and then to zooplankton at mysis stage.

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  3. Brackish water fin fishs – Biology and culture
    Brackish water fish farming is a system of aquaculture
    that focuses on the production of quality fin and shell fish
    that are found in the creeks, lagoons, and estuaries through
    rational rearing. It has a capacity of bridging through
    wide gap between fish demand and supply.
    Aquaculture has been defined by the Japanese Resource Council, Science and Technology Agency as under:

    “Aquaculture is an industrial process of raising aquatic organisms up to final commercial production within properly partitioned aquatic areas, controlling the environmental factors and administering the life history of the organism positively and it has to be considered as an independent industry from the fisheries hitherto.”

    Aquaculture is organised production of a crop in the aquatic medium. The crop may be that of an animal or a plant. Naturally, the organism cultured has to be ordained by nature as aquatic.
    Examples are:
    Fin fish: Tilapia, carp, trout, milkfish, bait minnow, yellow tail, mullet, cat fish.
    Shellfish: Shrimps, prawns, oysters, mussels, pearl oyster for cultured pearls

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