Integrated Tropical Coastal Zone Management: Application and Practices in Asia
SHRIMP-BASED FARMING SYSTEMS
IN THE SOUTHWESTERN COASTAL ZONE OF BANGLADESH
S.M. Nazmul Alam1
Key words: Small-scale shrimp aquaculture, paddy farming, disease, economics
Shrimp culture has become a majority activity in many parts of the coastal area of Bangladesh. The
culture system uses basically the same methods throughout the country and it can be loosely categorized
into traditional or improved traditional practices. It has often been said that the development of shrimp
culture has been unplanned, resulting in diseases, deforestation, reduction of soil fertility and agricultural
land, and ultimately social conflicts. However, the present scenario in the area has changed remarkably.
Large shrimp farm areas have been fragmented into smaller sized farms. The influential outsiders
have mostly gone away. Landowners are now successfully farming shrimp and other diverse crops.
Many social problems have been reduced greatly (DOF, 2001).
Coastal shrimp aquaculture in Bangladesh is mainly confined to two regions, namely, Khulna and
Chittagong. Two-thirds of the farms in the southwest (Khulna region) rotate paddy cultivation with
shrimp farming; in the highly saline conditions of the southeast (Chittagong region), salt production is
commonly rotated with shrimp. Shrimp culture in the Khulna region occurs in the dry months followed
by a crop of a local variety of transplanted aman2 rice in the wet months from July to August and
November to December on the same land inside the farm. The black tiger shrimp (Penaeus monodon)
is farmed predominantly under traditional (extensive) or improved extensive farming systems and the
annual yield ranges from 100-200 kg/ha. Homestead vegetable cultivation provides extra income.
Since the early 1980s the Government of Bangladesh (GOB) has been endeavouring to improve
the traditional culture practices, as the increase of land area has not been positively proportionate to
the increase of production. In response to this inefficient growth, the GOB launched infrastructure
development programmes together with technology demonstrations, extension, and training to improve
coastal shrimp aquaculture through various development projects.
Social inequality, insufficient infrastructure, and traditional farming methods all contribute to the
low productivity of shrimp and other farming practices resulting in poor living conditions and economic
loss. With increasing population pressure, however, there is a need for diversification and intensification
of different farm enterprises in order to conform with the environmental balance and improve socio-
economic conditions. Therefore, understanding the current farming practices and the difficulties facing
the shrimp culture area is necessary for the promotion of diversified farming.
1 MSc. Thesis (Ref. No. AQ-02-20), Asian Institute of Technology, Bangkok, Thailand, August 2002. Examination Committee
– Prof. C. Kwei Lin (Chair), Dr. Amararatne Yakupitiyage (Co-chair), Dr. Harvey Demaine, Dr. Michael J. Phillips
2 aman: paddy cultivation season
The overall objective of this study was to identify better options in order to contribute to the
improved management of small-scale shrimp aquaculture in shrimp-paddy zones in Bangladesh. More
specifically the study aimed:
§To identify present farming systems under different ownership arrangements.
§To assess the cost and benefits of coastal shrimp farming systems with respect to ownership
§To identify the factors that affect the improvement of shrimp management practices.
§To recommend improved shrimp-farming management systems.
The study area
The study area is situated in southwestern Bangladesh (between 22º 11' and 22º 17' N and 89º 03' and
89º 12' E); it is bounded by the Unions of Burigoalinee, Ishwaripur, Shyamnagar sadar, and Nurnagar
to the north. The world’s single largest area of productive mangrove forest, the Sundarbans (the
home of the Royal Bengal Tiger) lies to the south and east and is separated by the Kadamtali, Malancha,
Dumkoli, and Chunkuri rivers. The Bay of Bengal lies beyond the Sundarbans in the south. The
Kalindi River borders India to the west. The research area covered 25 villages of three Unions,
namely, Munshiganj, Ramjannagar, and Kaikhali encompassing 6 248 ha of the Shyamnagar Upazila3
of Satkhira District. The study focused on the local level and the framework for data collection was
based on the following farm ownership arrangements:
§Individual owner: The farm land is owned and operated by one person.
§Farmers’ group: The farm land is owned by a number of persons who all play an active role in
operating the farm.
§Outside lease: The farm land is leased out by the landowners to a person or persons living
outside the polder.
The study was based on primary and secondary data sources. The data were collected from January
to August 2002 from the groups given in Table 1 using a questionnaire and PRA (participatory rural
appraisal) tools (transact analysis, focus group discussion, and seasonal calendar). Random sampling
was also used.
3 An Upazila is a sub-district and a government administration centre at the local level. It consists of a number of unions of
Table 1. Sample size for the study
Farms Individual farmer Group farmer Outside farmer
Exist Taken Exist Taken Exist Taken
Shrimp 225 35 210 31 09 03
Shrimp+paddy 65 13 N/A ** N/A **
Paddy 200+ 28 N/A ** N/A **
N/A: not available
The collected data were combined and summarized into tabular form and classified according to farm
ownership arrangements. The data were analysed using MS Excel® and SPSS software.
In order to understand the cost and returns incurred within a one-year production period, some
economic indicators like net profit, gross margin, return to total cost, and return to labour were analysed
to compare the economic efficiency among the farming systems and different categories of ownership.
Results and discussion
Cropping patterns in the study area
The following cropping patterns were found in the study area. Each of the farming practices is
§Homestead vegetable cultivation
The transect analysis in Figure 1 indicates the existing land-use patterns of the study area. Resources
were identified through a cross-walk from 22o 12′ N (89o 03′ E) to 22o 15′ N (89o 11′ E) and different
land use, cropping pattern, and seasonality were observed.
Figure 1. Transect showing the land-use pattern of the study area
Shrimp farms along with scattered human settlement were close to the periphery of the
embankment/dike. Year-round shrimp culture with multi-stocking and multi-harvesting has been
practised for two decades as salinity in the nearby river is found throughout the year. Paddy, the main
agricultural crop of the country has been cultivated since time immemorial.
Coastal people, like other rural people in Bangladesh, depend on agriculture for their livelihoods. With
the establishment of shrimp culture activities, farmers changed their practices and diversified their
occupations as well. Different cropping systems were observed in the study area over three main
§Rabi season (winter): November to February
§Pre-Kharif season (summer-I): March to May
§Kharif season (summer-II): June to October
Shrimp-shrimp-shrimp and (a few) shrimp-shrimp-(shrimp + paddy) were identified as the major
systems covering 55 percent of the study area. Similarly fallow-fallow-transplanted aman paddy was
practised in 30 percent of the area. Free space, around the homestead (if available) was used for
vegetables almost throughout the year and covered 5 percent of the study area.
Farmers use their own land that was formerly used for rice and employ the natural rearing process in
its simplest form. The farming period lasts from February to the end of November with multiple
stocking and multiple harvesting methods. The respondent farmers used almost uniform management
activities for pond preparation and grow out. However, the application rate of fertilizer, stocking
density of post larvae, and water-exchange rates varied from farmer to farmer.
The investigated farms were in the inter-tidal range. There was no “unique” design followed by
any category of shrimp farmer. All the categories used the open system, with no treatment ponds. The
ground topography of the surveyed farms was irregular. The average water depth in the ponds was
0.61 m. Generally 11 to 13 cm of the water level was reduced at 14- to 15-day intervals; 20 to 30
percent of the pond water volume was exchanged during tidal regimes and farm effluent was discharged
directly to the common flushing/drainage canal.
The shape of the farms was either rectangular or irregular with a large surface area. The variation
of farm size in different categories was distinctly noticeable. Farms under shrimp + paddy were
generally smaller (1.29 ha) followed by the individual shrimp category (2.28 ha). The largest farm
was operated by an outside lessee (36.44 ha). The average area among the categories was 3.59 ha
which was lower than the findings (10 ha in Shyamnagar Thana4) by Hoq et al. (1997). In other
Upazilas under Satkhira District they found that the farm area was under 50 ha (average 27 ha). The
findings from the study revealed that the farm sizes are becoming smaller day by day and most of the
farms are operated by individual or group enterprises.
4 Thana: same as Upazila
Pond preparation is an important activity at the start of each culture period. Pond dikes are constructed
manually – 0.4 to 1.2 m high – and the width of the dike varies from 0.2 to 0.7 m. The dikes are built
by excavating topsoil adjacent to them; thus shallow canals along the periphery of the dikes are
created to retain water and they act as shrimp refuges. Generally the water of the old shrimp pond
disappears at the end of November and it is left empty for a month. The farmers during this time
repair the dikes, sluice gate, guard shed, and other infrastructures.
After drying and tilling, the pond is filled with tidal water up to six inches. The smaller farmers
usually plough at this stage. Water is raised at intervals when introducing each input. Agricultural
limestone (CaCo3) is applied after two days of insecticide application. The average application rate of
lime by all categories was 82.82 kg/ha. The individual category used a lower rate of lime
(67.37 kg/ha) compared to others. The limestone is soaked with water in a drum for the whole night
and applied over the farm the following day. After three to five days of liming, the pond is applied with
cow dung (750-1 000 kg/ha). The farmers in the shrimp + paddy category used the highest quantity of
cow dung (1 316.91 kg/ha). Inputs like urea, triple superphosphate (TSP), diammonium phosphate
(DAP), mustard cake and others such as zinc and potash were used by different categories for
improving pond productivity.
Shrimp fry stocking management
Shrimp farms under different ownerships stocked varying amounts of fry. Most farmers in all categories
stocked shrimp post larvae directly in ponds, while a few of them nursed fry in nursery ponds before
transfer to grow out ponds.
Smaller farms stocked higher densities than larger farms. Individual shrimp farmers preferred to
stock the farm more densely with fry (19 642 fry/ha) than the other categories. The shrimp + paddy
farm with a mean farm size of 1.29 ha stocked 18 352 fry/ha. The outsider with the largest farm area
stocked only 13 437.39 fry/ha. Overall the average stocking density in the study area was 17 110 fry/
ha which was within the range of the findings (15 000 to 40 000 fry/ha) of Hoq et al. (1997). On
average the farmers stocked 1.8 fry/m2. ANOVA showed that the mean stocking densities under the
individual category were significantly (P<0.05) higher than those of the outside category.
In the study area farmers in all categories re-stocked their ponds with fry more than five times,
and harvested 16 times or more in their farming calendar. This was attributable to the availability of
saline water throughout the year in nearby rivers and canals. Almost all categories of shrimp farmers
completed stocking between February and April and harvested between April and November.
Shrimp post larvae in different categories suffered losses of 76 percent. The outsider’s large
farm had the highest survival rate of post larvae (45 percent) while the lowest survival rate was in
shrimp + paddy farming (23 percent). The individual and group farmers had survival rates of
24 percent and 26 percent respectively. This also supports the report of Karim and Stellwagen (1998)
who noted that coastal shrimp aquaculture had an estimated 20 percent survival rate for stocked post
larvae, revealing a post stocking wastage of post larvae.
Health and disease management
Farmers in all categories checked shrimp growth randomly and throughout the production cycle by
hand and cast nets. The body colour, size variation, external gut, and carapace were checked by all
categories of farmers who used a combination of checking methods. Over 90 percent of the farmers
from the individual, group, and shrimp + paddy categories used random sampling while the outside
farmers checked weekly (33 percent) and randomly (67 percent) respectively. The individual category
checked for all possible symptoms in shrimp. Gills were not checked by other categories. Shrimp
diseases have become a regular occurrence since 1995. All categories admitted the appearance of
shrimp diseases in 2001.
The affected farmers also took different measures to cope with shrimp diseases. Most of the
farmers harvested early when shrimp disease occurred in their or neighbouring farms. Some farmers
converted a portion of the farm to paddy culture during the monsoon period to avert the risk. Farmers
tended to use chemicals like Thiodan during the appearance of diseases. Water quality improvement
measures were not practised except for exchange of water during tidal shifts. When the extent of the
disease was severe, farmers drained all the water and let the bottom dry under the sun. The remaining
shrimp took refuge in the canal along the periphery of the farm. After drying, the pond was filled again
with brackish water and stocking took place.
Harvesting and marketing management
Harvesting usually takes place during full and new moons. The used water is drained out to the canal.
Then fresh tidal water from the canal is introduced into the pond. The following methods were used
for harvesting shrimp in the study area:
Gai method: A very small portion of the farm is converted into a rectangular-shaped harvesting
area. This area is prepared adjacent to the canal and it is surrounded with soil dikes, locally known as
Gai. One wooden gate and a bamboo/plastic pipe fence are accessories to make a catchment area
inside the Gai. Sometimes the outside lessee used concrete floors for the Gai.
Trap method: Trapping is another way of harvesting shrimp. Bamboo traps, locally called Aatol
and of various sizes (standard 2 x 2.5 x 2 feet) are placed at 8-to-10 foot intervals from the periphery
to the inside of the farm. Fine-meshed net is attached to each of the traps. The Aatol is also placed at
the attachment of the main pata of the Gai. Large shrimp farms install Aatol frequently.
Net method: Cast nets are used for harvesting the shrimp as farmers obtain fewer shrimp via the
Gai trap method. The farmer hires cast-net owners. The netters stand close to each other and cast
the net together. Thus they advance, casting nets all over the farm and harvesting the shrimp.
The harvested shrimp are then kept in bamboo crates/coops. They are washed with saline water
and placed in heaps at the chatan (a place to sort and sell shrimp) to prepare for sale at the farm gate.
The buyer comes to the farm gate, bargains for, and settles the selling price. Sometimes selling by
auction takes place if buyers are numerous. The bid winner occasionally shares the lot with other
fellow buyers and thus maintains social harmony in the locality. The shrimp are then taken to the local
depot for icing and are forwarded to the processing plant within the shortest possible time for decapitation
and onward dressing.
Rain-fed transplanted aman paddy is the main agricultural crop in the study area. The use of traditional
rice varieties was replaced by high yield and salinity tolerance varieties because of the geographical
location. The varieties were BR-10, BR-11, BR-22, BR-23, and BR-30 developed by the Bangladesh
Rice Research Institute. This paddy is grown during the monsoon season for four months: activities
include seed bed preparation, grow out land preparation, transplantation, and harvesting. The paddy
fields of the study area remain idle after harvesting and are used as grazing land for cattle.
The paddy farms in the study area were located in the supra-tidal zone. The farms were separated
from the adjacent shrimp farms by a road and a few villages. The configuration of the farms was
rectangular or square or irregular, with a smaller surface area than the paddy fields. Surveyed farms
varied between 0.22 and 4.41 ha with an average size of 1.68 ha.
Preparation of the paddy field
The paddy fields were flooded with rain water to soak the soil for a week. Then the soaked rice fields
were tilled repeatedly with a tractor until the soil became puddled. The farmers used a portion (0.006
ha) of the grow out field (0.13 ha) as a nursery for preparing seedlings. The seed bed was filled with
water up to a height of 20 to 25 cm. The nursery was then used as a grow out paddy field once the
seedlings were extracted. The 25- to 30-day seedlings were then transplanted to the grow out field.
The straight row planting method was followed using 4-5 seedlings/hole. Water was directed from the
canal into the paddy fields twice a week, which often received rain water.
The application rate of fertilizer differed from one farm to another depending on the economic
status of the farmers. Urea (60 kg/ha) and TSP (50 kg/ha) were common fertilizers. No organic
fertilizers such as cow dung or green manure were used because of the large quantities required and
scarcity in the coastal area owing to the lower numbers of cattle.
The paddy was attacked by various pest and diseases. Brown leaves and viruses were commonly
observed. Farmers used Diajenon 60 EC (0.8 L/ha) and Melathion (0.7 L/ha) to disinfect the paddy.
Weeds were also controlled manually.
The farmers harvested paddy when the grains ripened. Usually it took 90 to 120 days to maturity and
harvest. The harvested paddy from the field was taken to the home for further processing, i.e. threshing,
cleaning, and drying. The farmers kept the good quality paddy as seeds for the next year. After
harvesting, the field was left fallow for eight months. The yield from paddy was around 3 000 kg/ha.
Shrimp and paddy farming
The practice of shrimp and paddy culture in combination is a new trend in the study area. It is
becoming popular to avert the risk of shrimp disease, which the majority of the shrimp farms have
experienced over the past few years. The small-scale individual shrimp farmers are practitioners.
Elevated land of the shrimp farm where water cannot be retained is converted for paddy cultivation
during the monsoon. The farmers conserve rain water in the canal at the periphery that has been
prepared for shrimp culture. The preparatory work for shrimp culture followed the practice described
earlier. During the monsoon period the farmers separate the paddy field from the shrimp farm by
building a dike. Paddy was not tilled or ploughed, as they believed that the saltwater would emerge
from the topsoil. A small portion of the elevated land was prepared for a seed nursery, and the
seedlings were then transplanted to the paddy area. The size of the paddy area in shrimp fields varied
(0.13 to1.60 ha) according to the land available.
Management of the farm
The farmers were experimenting with the new system by using rain water and brackish water at the
same time and with two different types of crops. They engaged mostly family labour for paddy while
they hired labour for shrimp farming. They used minimal amounts of fertilizer for paddy.
Homestead vegetable cultivation
Vegetable cultivation was a supplementary farming enterprise. Products grow more quickly than
other crops and contribute to family consumption needs as well as household income. Vegetables are
grown almost year round but most of the vegetable growers prefer to cultivate in the early dry and
early wet season since there is enough rain water and the soil still holds enough moisture for vegetable
Usually, the farmers who had access to enough water for both home use and irrigation started
growing vegetables in December. The second growing season started in April. Vegetables grown
were: spinach, amaranth, radish, chilli, cabbage, cauliflower, potato, pumpkin, lady’s finger, snake
gourd, turnip, and ridge gourd.
The land is prepared with a spade and by harrowing. Grass and weeds are removed. Beds are
carefully prepared to make the soil soft and more level. The size of each bed is usually small, (2-5 m
wide). The average available land for homestead vegetation ranged from 0.02 to 0.06 ha. Animal
manure and some chemical fertilizer (Furadan at 12 L/ha) were applied as dressing during the period.
On average poultry droppings (7 480 kg/ha); DAP (490 kg/ha), muriate of potash (120 L/ha), and
mustard cake (165 kg/ha) were used during the preparatory stage. Gypsum (187 kg/ha) was sometimes
used to reduce the salinity of the soil. Use of urea was negligible.
Broadcasting and row seeding were used during sowing – broadcasting for radish, chilli, and
cauliflower and row seeding for ridge gourd, bitter gourd, luffa, and string bean. Rice straw was used
as mulch after sowing to avoid direct sunlight, reduce moisture loss, lessen soil compaction, decrease
competition between the vegetables and weeds, and increase soil organic matter.
An estimated Tk9 3505 was invested in chemicals and fertilizer while Tk 610 was spent on seeds
and seedlings for each hectare of vegetable production. A farmer can earn more than
Tk100 000/ha by producing vegetables from the homeyard.
Cost and benefit analysis of shrimp farming
Yield from the shrimp farms
The results suggested yields of Penaeus monodon ranging from 108.88 to 146.39 kg/ha with a mean
yield of 140.06 kg/ha for the different categories of farmers indicating lower productivity (Table 2).
Among the gross yield of the shrimp farms, 51 percent of the total weight came from only Penaeus
monodon while the remaining 18 percent and 31 percent came respectively from other shrimp and fin
fish (Figure 2).
5 US$1.00 = Tk58.50 in August 2002 (Tk: taka).
Table 2. Gross yield (kg/ha/yr) from shrimp farms by different category
Species Unit Categories
Ind.(n=35) Gr.(n=31) Out.(n=03) S+P(n=13) All(n=82)
Shrimp kg/ha 146.39 153.12 151.86 108.88 140.06
Minimum 07.48 20.84 89.76 18.70 7.49
Maximum 455.03 306.68 199.62 249.83 455.03
SD 104.73 70.90 56.32 70.97 86.74
Other shrimp kg/ha 72.43 68.01 27.51 27.57 48.88
Minimum 6.23 2.05 3.93 3.59 2.05
Maximum 164.56 213.93 40.77 80.41 213.93
SD 41.22 47.79 20.47 25.49 44.28
Fin fish kg/ha 103.29 96.27 59.42 77.09 84.01
Minimum 5.82 18.01 48.48 11.97 5.82
Maximum 431.54 303.60 74.80 299.20 431.54
SD 79.12 74.44 13.70 87.16 7.06
All kg/ha 322.11 317.40 238.79 213.54 272.96
Ind: individual farmer, Gr: group farmer, Out: outsider, S+P: shrimp + paddy farmer
Various authors have quoted different production rates irrespective of culture practice (62-206
kg/ha/yr [Rahman et al., 1994]; 97.4-225.6 kg/ha/yr [Hoq et al., 1995]; 125.15 kg/ha/yr [FAO, 1997]).
According to FAO (1997), P. monodon contributed 50 percent, while other shrimp contributed
25 percent to total farm production. The rest (25 percent) came from fin fish. The present findings
also found variations among the species and by category. The average contribution from P. monodon
was 51 percent (Figure 2). The outsider achieved 63 percent from P. monodon production and
12 percent and 25 percent from other shrimp and fin fish respectively. This indicated that the outsider
only concentrated on P. monodon production.
Figure 2. Percentage of biomass and value from the shrimp farm by farmer categories
(kg) Value (tk) Biomass
(kg) Value (tk) Biomass
(kg) Value (tk) Biomass
(kg) Value (tk)
Individual Group Outsider All
Shrimp Other shrimp Fin fish
The second beneficiary from P. monodon was the shrimp + paddy farm owners. They achieved
51 percent from P. monodon production with 18 percent from other shrimp and 36 percent from fin
fish respectively. The individual category achieved 46 percent while the group farmers achieved 48
percent from P. monodon production on their farms. Fin fish provided a significant contribution in
terms of food and income generation in the individual, group, and outside categories.
Cost of production
The cost of production of the surveyed farms in the study area was analysed (Table 3) to determine
the cost and return for P. monodon and others. The main costs were preparation of land, rent, labour,
fry, and fertilizers. It appeared that the greatest expense for shrimp farms was the cost of fingerlings
(39 percent [individual], 37 percent [group], 44 percent [outside], and 32 percent [shrimp + paddy
farmers]). Next was rent: 30 percent (individual), 38 percent (group), 31 percent (outside), and 25
percent (shrimp + paddy farmers) respectively. Labour ranged from 9 to 13 percent of the total cost.
These three major production costs constituted 67 to 81 percent of the total cost of shrimp
farming and greatly differed from the findings of a case study on shrimp aquaculture management in
Bangladesh by WB/NACA/WWF/FAO (2002). This report indicated that these three major production
costs constituted 94 percent of the total cost of shrimp farming. The feed and fertilizer costs by
different category ranged from less than 1 percent and 2.3 to 5.2 percent of the total cost. The total
production costs were relatively lower for the extensive shrimp farming systems than more intensive
systems. Leung and Sharma (2001) found that seed cost comprised a large share of the total production
cost in Bangladesh (43.5 percent), Indonesia (32.7 percent), India (22.4 percent), and Sri Lanka (22.7
The paddy costs for the shrimp + paddy farmer were lower than the costs of the mono paddy
farmer. In both cases the highest cost was labour. But the shrimp + paddy farmer used more labour
(57 percent) than the mono paddy farmer (46 percent). Seeds ranked second among the total cost (16
percent and 13 percent respectively). However, the total cost of inputs was higher in the paddy farm
than the shrimp + paddy farm.
It is evident that shrimp farming is considered socially inefficient because of its low labour absorption
capacity, compared to paddy cultivation. Shrimp culture required 15 to 34 man-days/ha, while paddy
only required 61 man-days/ha. But in the shrimp + paddy category the farm needed only 31 man-
days/ha for paddy cultivation (Tables 4 and 5).
Gross return (Tk/ha) was analysed (Table 3). The total annual revenue from shrimp farms was
calculated to include sales of other shrimp (Penaeus indicus, Metapenaeus monoceros, M.
brevicornis) and fin fish (Oreochromis nilotica, Mugil parsia, Lates calcarifer, Mystus gulio)
that were raised in conjunction with cultured shrimp (P. monodon). The group farmers managed
higher total returns than the other three categories. The outsider received the highest (90 percent)
amount from Penaeus monodon. On average 85 percent of the revenue came from Penaeus monodon
while 8 percent and 7 percent came from other shrimp and fin fish respectively.
Table 3. Gross return (Tk/ha/yr) from shrimp farms by different category
Species Unit Categories
Ind.(n=35) Gr.(n=31) Out.(n=03) S+P(n=13) All(n=82)
Shrimp Tk/ha 40 307.04 44 402.66 44 143.67 30 058.55 39 727.98
%81 82 90 87 85
Min. 1 870.00 4 136.97 23 320.00 4 114.00 1 870.00
Max 122 796.67 89 760.00 63 954.00 67 320.00 122 796.67
SD 28 882.85 21 698.00 20 335.94 20 260.84 24 887.49
Other shrimp Tk/ha 5 475.34 5 272.29 2 956.62 1 993.63 3 924.47
%11 10 06 06 08
Min. 623.33 292.17 2 640.00 335.48 292.17
Max 11 507.69 14 960.00 3 459.50 5 610.00 14 960.00
SD 3 052.27 3 687.83 440.35 1 774.17 3 330.01
Fin fish Tk/ha 4 217.49 4 213.57 2 158.91 2 297.04 3 221.75
%08 08 04 07 07
Min. 207.78 1 038.89 1 939.26 239.36 207.78
Max 17 261.54 16 622.22 2 337.50 6 732.00 17 261.54
SD 3 288.46 3 412.99 202.27 1 739.04 3 147.10
All Tk/ha 49 999.87 53 888.52 49 259.20 34 349.22 46 874.20
%100 100 100 100 100
Ind: individual farmer, Gr: group farmer, Out: outsider, S+P: shrimp + paddy farmer
The average gross income from shrimp farm was Tk46 874/ha. This figure differs from the
findings of BCAS (2001) in which revenues from shrimp farms fell in the range of Tk55 000 to 63
000/ha, with the variations reflecting higher yields of shrimp per hectare. The income from P. monodon
made a dominant contribution to gross income (Tk39 728/ha), which accumulated 85 percent of the
income singularly. Other shrimp accounted for Tk3 924/ha (8 percent) followed by fin fish (7 percent).
The average gross margin of shrimp production was negative in the three farm ownership categories,
and the returns to the variable cost of shrimp production under the categories were also low (0.78,
0.88, and 0.73 respectively). This means that for every one taka of investment on a shrimp farm, the
return is Tk0.78, 0.88, and 0.73 for the individual, group, and outsider categories respectively (Table
4). The return to labour for different categories was 407, 274, and 1 163 respectively.
Table 4. Comparison of shrimp farm economics by different categories
Items Unit Ownership category
Individual Group Outsider
Gross yield kg/ha 322.11 317.40 238.79
Total cost Tk/ha 63 437.57 61 025.24 66 697.01
Gross return Tk/ha 49 999.87 53 888.52 49 259.20
Min. 4 155.56 6 808.40 28 160.00
Max 129 653.33 100 980.00 69 751.00
SD 31 549.45 24 021.59 20 802.15
Gross margin Tk/ha (13 437.70) (7 136.48) (17 438.01)
Min. (95 230.37) (71 901.50) (6 239.25)
Max 64 396.00 74 833.66 66 373.04
SD 34 417.53 28 765.66 21 698.28
Return to total cost Tk 0.78 0.88 0.73
Total labour no/ha 33 26 15
Return to labour Tk 407.20 274.48 1 162.53
US$1.00 = Tk58.50 in August 2002
There was a sharp loss from the shrimp farm against the total production cost. If the rent is
excluded from the total cost then there was a margin of profit in shrimp farming. The benefit cost
ratio was then 1.08 (individual), 1.35 (group), and 1.07 (outsider) respectively. If the rent was included
then the benefit cost ratio was 0.78 (individual), 0.88 (group), and 0.73 (outsider) respectively, which
indicated loss in shrimp farming.
Leung and Sharma (2001) observed that the profit per kg of shrimp produced in eight countries
involved in extensive shrimp farming ranged from US$4.67/kg in the Philippines to US$-0.31/kg in
Vietnam. Bangladesh was ranked 4 out of 8 with a profit of US$2.83/kg, with costs of US$4.07/kg.
The cost of production in other extensive shrimp-producing countries ranged from US$1.62/kg in
China to US$4.42/kg in India. The study showed that the yield of shrimp in extensive shrimp farming
in Bangladesh was 216 kg/ha/yr. The farm gate price was US$6.90. The present findings from the
study showed a massive loss in terms of income from shrimp farming. The production cost per kg of
shrimp ranged from US$6.81 to US$7.54 (including rent) with an average of US$7.25. The average
farm gate selling price of shrimp was US$4.83/kg in the study area. As a result, the highest production
cost/ha and the lowest farm gate sale of shrimp earned a negative profit of US$2.48.
Economic returns by different farms
The average gross margin analysis for the three farming systems per ha is summarized in Table 5.
The gross margin was negative for shrimp while it was positive for shrimp + paddy and paddy
monoculture. The gross margin of paddy was lower in shrimp + paddy (Tk6 256/ha) than in paddy
monoculture (Tk14 343/ha). The return to variable cost was also higher in paddy (2.65) than in shrimp
+ paddy. However, there was much variation in the total labour requirement under different farming
systems. The return per labour was significantly (P< 0.05) higher in paddy monoculture than in shrimp
+ paddy culture.
Table 5. Comparison of different farm economics
Items Unit Farm category
Shrimp Shrimp + paddy Paddy
Gross yield kg/ha 322.11 213.54 + 1 583.26 2 701.42
Total cost Tk/ha 63 437.54 64 505.84 + 5 062.90 8 692.36
Gross return Tk/ha 49 999.87 34 349.22 + 11 318.77 23 034.99
Min 4 155.56 5 684.80 + 00.00 145.44
Max 129 653.33 71 060.00 + 22 440.00 39 893.33
Gross margin Tk/ha (13 437.67) (30 156.62) + 6 255.87 14 342.63
Min. (95 230.37) (1 256.64) + (00.00) (2 518.27)
Max 64 396.00 55 370.70 + 18 235.50 36 303.20
Return to total cost Tk 0.78 0.53 + 2.23 2.65
Total labour no/ha 33 34 + 31 61
Return to labour Tk 407.20 886.95 + 201.80 235.12
Factors affecting management practices
The factors that affected the improvement of shrimp management systems are discussed below.
Shrimp had been farmed in the study area for more than three decades. During a prolonged culture
period a layer of anaerobic sediment is deposited on the pond bottom and micro-organisms consume
more oxygen and produce high quantities of CO2, hydrogen sulphide, ammoniacal nitrogen, and nitrite
nitrogen which are very harmful to shrimp. Siltation was more severe in ponds which were constructed
on elevated land that received water during full and new moons. Such ponds were unsuitable for
shrimp farming and production deteriorated over time. Lack of good infrastructure facilities like sluice
gates and canals also limited the access of water.
Water exchange and inadequate flushing of ponds
In the study area the rivers are tidal and salinity exists throughout the year with seasonal variations
providing suitable conditions for brackish water aquaculture. The tidal fluctuation decreases both in
daily amplitude and the spring tide peaks during the new and full moons (twice daily). This limits the
amount of water for flushing the ponds. Most of the farmers could not flood their ponds because of
the narrowing width of the gate and resulting inadequate water height in the ponds. Influential farmers
or landowners or outside farm owners sometimes monopolized the water-gate system in the polder
areas; this affected both the shrimp and agricultural farmers. Moreover, the canal systems in the
study area were also affected by siltation resulting in limited flow of water into the ponds. Due to
shallow water in most of the farms, the microbial blue green algae died and decomposed due to
excess heat in the bottom soil. Decomposition of blue green algae created acidity in the pond bottom,
which was harmful for shrimp.
Soil and water characteristics
Acid soils in the area lowered the alkalinity of brackish water resulting in soft shelling of the shrimp.
Typically the solution for acid soils is the application of lime (CaO to neutralize, CaCO3 to improve
alkalinity). The low water exchange ponds required increasing amounts of lime applications.
Stocking density and feeding
Shrimp post larvae along with other incoming fry during tides were likely to be attacked by predators
soon after stocking. Stocking at intervals throughout the year had poor results unless shrimp were
reared in a nursery beforehand. Competition between shrimp species undoubtedly limited P. monodon
yield. Besides, there was no supplemental feeding which is required after a certain age. During this
stage shrimp do not like to consume phytoplankton and this excessive plankton died, polluting the
ponds. Moreover the likely presence of several predatory fish species reduced the yield of shrimp.
There was a major tendency to attribute shrimp mortality and production losses to diseases in the
In 1995, some brood stock collected by a commercial trawler, showed white spots on the carapace,
indicating that white spot disease had spread to wild stocks of P. monodon (Rahman, 1999). So
another likely source is transmission from infected brood stock to the eggs in hatcheries thereby
causing high levels of infection in nurtured post larvae. Moreover, there is no quality assurance system
to ensure that farmers are receiving good quality post larvae from the hatcheries.
Another problem was that there were no good sources of water. Thousands of farms were
developing in an unplanned manner. Water was taken from one farm to another farm. If one farm
was attacked by disease the neighbouring farm automatically became infected.
Usually, the stressful conditions in ponds did not appear separately. In most cases several stressful
conditions occurred simultaneously as their effects in the pond environment were linked. The results
of these stress combinations were usually more severe than any single stress factor. The unwanted
fin fish and other shrimp also competed with the natural food in the shrimp farm. Moreover, predatory
fin fish devoured young shrimp. The horn shell mollusk (Cerithedia cingulata) was also abundant in
shrimp farms; it competes with shrimp for natural feed.
The farmers in the study area suffered a wide range of negative social impacts due to disease outbreak
among shrimp in 2001. Both crops and employment experienced losses. Many farmers restocked at
lower densities immediately after loss and recovered part of their early losses. During disease outbreaks
massive unemployment occurred mainly for part-time labourers.
Farmers lacked money to pay for rent and other essential costs. Shrimp farming is capital intensive
and in most cases farmers had to borrow money from different sources with interest. Any negative
result on the farming sector resulted in corresponding losses in other linked industries. As many
farmers purchased fry on credit, their inability to repay these debts in a timely fashion caused civil
disorder in the area. A few farmers migrated to a neighbouring country to avoid harassment by
moneylenders. Some farmers were reluctant to practise shrimp culture again.
The unity and the trust among the members in the group enterprise wavered and many of these
farms fragmented into individual farms. The new farms again faced problems with water management
Many of the farmers used poisonous chemicals like Thiodan and Dimicron to disinfect the ponds.
The diseased shrimp died from Thiodan application. There was a belief in the study area that after
using Thiodan the colour of the water becomes greenish and a few days later shrimp appear. When
farmers achieved good results from using Thiodan, they would dismiss advice to avoid its use in the
The findings from the study area revealed that almost all farmers applied fertilizers during preparation
of the grow out ponds. But the farmers did not use the correct types of fertilizers in correct ratios to
avoid increasing operating costs and fear of infecting the ponds with diseases. During the growing
period, the farmers did not feed the shrimp; only a few farmers used compost as feed. The increasing
price of other inputs sometimes discouraged the farmers from further investment.
Profitability was highly sensitive to farm rent charges in the study area. Rent for sub-lessees was
a critical factor in the economic viability of the farm. The rent was Tk18 700-22 440 /ha, which was
the second highest cost after fry in the production systems. The individual and group farmers did not
consider rent in production cost. However, from the economic perspective the value of rent was
considered and calculated accordingly, revealing a higher rate of investment per hectare in the shrimp
Profit was also highly sensitive to sale price in all categories. If shrimps are harvested when they
are too small then profit will be greatly reduced. Most of the surveyed farms harvested small-sized
shrimp because of diseases and suffered great loss. Similarly, any effects of markets on shrimp price
definitely influence farm viability. The small-sized harvested shrimp had to be sold at a lower price
(Tk190-270/kg) at the farm gate, and thus incurred negative profit. The harvesting of other species
contributed little to income, but was significant in terms of food security for the farmers.
It is evident from the overall analysis that shrimp farming in the study area has both positive and
negative attributes including income and employment generation, local resource utilization, risk and
uncertainty, and social disharmony. Although yield and return are not satisfactory, yet enthusiastic
local people practise shrimp farming. Diverse cropping patterns were observed (such as paddy
cultivation via conversion of a part of the shrimp area during the monsoon).
Shrimp farming (mono and with paddy) was the major activity almost throughout the year and
covered 55 percent of the study area. Transplanted aman paddy was cultivated in 30 percent of the
area while vegetables were cultivated in the homestead. The yield and return from paddy in shrimp
land were much lower than paddy monoculture.
The farming system is still extensive in nature, depending on tides, natural feed, and supplementary
stock of post larvae. Variation in farming systems in terms of cost, investment, and management were
observed among the different farm ownerships. The yield and return from shrimp farming also varied
among different farm ownerships. The average yield was 140 kg/ha; the group farm achieved the
highest figure (153 kg/ha). The outsider maximized yield from P. monodon. Other farm owners put
emphasis on other shrimp and fin fish.
The returns from farm production also varied among ownerships. Due to mass mortality of
shrimp in 2001, farmers in all categories experienced major losses. The average gross income from
shrimp farming was Tk46 874/ha. The outsider maximized 96 percent income from P. monodon and
Several human, environmental, and related factors affected shrimp production. Poor farm
management resulting in disease caused mass shrimp mortality and affected the livelihoods of the
small-scale shrimp farmer to a large extent. The contribution from the shrimp culture industry, in
general, has been appreciated for impressive production, export earnings, generation of local
employment, and facilitating growth of associated industries and services.
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