An experimental culture practice of P. monodon on extension approach was conducted in two brackish water earthen ponds of Demonstration Farm and Training Center (DFTC), Kaliganj, Satkhira. The experiment was aimed to provide farmers with appropriate technology that can immediately improve pond yield with keeping the environment in friendly condition. For optimization of stocking density of a cost effective environmental friendly improved extensive shrimp farming, the ponds were stocked with coastal river post larvae of P. monodon at the stocking rates of 2 pls/m² and 2.5 pls/m² without supplementary feeding. To control experimental error another five farmer's gher were used as replicates of each demo-pond. Considering the farmers buying ability, cost of inputs and other facilities kept minimal. The impact of stocking density was evaluated on the basis of growth, survival rate, production and economic return. Better production (average 299.01 kg/ha) with same survival rate (39.33%) were found with a stocking density of 2.5 pls/m² without causing any deterioration in the culture environment

Ahmed, S.U.

Roy, P.K.

Shofiquzzoha, A.F.M.

Aquatic Commons

Bangladesh J. Fish. Res., 3(2), 1999: 137-143 
Optimization of stocking density for environmental-
friendly improved extensive shrimp farming system in 
south-west part of Bangladesh 
P.K. Roy, S.U. Ahmed* and A.F.M. Shofiquzzoha 
Bangladesh Fisheries Research Institute, Brackishzvater Station, Khulna 9280, Bangladeesh 
*Corresponding author 
Abstract 
An experimental culture practice of P. monodon on extension approach was 
conducted in two brackishwater earthen ponds of Demonstration Farm and Training 
Center (DFTC), Kaliganj, Satkhira. The experiment was aimed to provide farmers 
with appropriate technology that can immediately improve pond yield with keeping 
the environment in friendly condition. For optimization of stocking density of a cost 
effective environmental friendly improved extensive shrimp farming, the ponds were 
stocked with coastal river post larvae of P. monodon at the stocking rates of 2 pls/m2 
and 2.5 pls/m2 without supplementary feeding. To control experimental error 
another five farmer's gher were used as replicates of each demo-pond. Considering 
the farmers buying ability, Cost of inputs and other facilities kept minimal. The 
impact of stocking density was evaluated on the basis of growth, survival rate, 
production and economic return. Better production (average 299.01 kg/ha) with 
same survival rate (39.33%) were found with a stocking density of 2.5 pls/m2 without 
causing any deterioration in the culture environment. 
Key words : P. monodon, Shrimp farming, Stocking density 
Introduction 
Shrimp farming are still major growth industries in many parts of Asia, Africa 
and Latin America (Rackowe et al. 1983) and represents an extremely valuable 
element in the economy of many developing countries as a major source of foreign 
exchange. In Bangladesh about 80% of total exportable shrimp produces from the 
districts of Satkhira, Khulna & Bagerhat (BBS 1996). Considering the enormous 
potentiality for export promotion from this sector, the government of Bangladesh 
merged the business into industrial sector. It is worthwhile to mention that avera'ge 
production of shrimp in this region is about 150 kg/ha/year through traditional and 
extensive method of cultivation with little exception. But there is still enough scope 
to increase the present production level through environmental friendly improved 
extensive shrimp farming. Therefore, Considering the prevailing fact, an experiment 
was undertaken to develop an optimum stocking rate with environmentally friendly 
improved extensive shrimp farming (in South-west part of Bangladesh) techniques. 
P.K. Roy et al. 
Materials and methods 
Experimental site 
Two ponds each of 1.25 ha was selected for this experiment in the demonstration 
shrimp farm qnd training center complex of the DOF at Kaligonj, Satkhira. Ten local 
farmer's gher more or less similar nature also selected for farmers contact as well as 
replicates of demo-pond. 
Experimental procedure 
The experiment was conducted during the month of April to August'96. There 
were two treatments with six replicates each. In T1, pond was stocked with a rate of 
2pls/m2 and for T2 it was 2.5pls/m
2
.Five farmer's gher were used as replicates for 
each treatment. No feed were supplemented dnring the culture operation. 
Pond preparation 
The ponds bottom were dried and tilt by tractor. Soil pH were tested and lime 
were added depending on the soil pH. Flushing gates were fenced using bamboo slits 
and nylon mesh screen. Water was introduced gradually at a minimum depth to 
facilitate the soil and lime interaction. Cowdung at the rate of 500kg/ha, mustard oil 
cake 100 kg/ha and phosphate+ urea 35 kg/ha (P:U = 3:1) were applied followed by 
addition of water up to a depth of 30~40 em and wait for natural feed development. 
Stocking 
Two J?Onds were stocked with locally available seed at the density of 2 pl/m2 and 
2.5 pls/m respectively. 
Water exchange and fertilizatiott 
In all the ponds water exchanged fortnightly during new moon and full moon. 
Inorganic fertilizer (urea and phosphate) were applied during the experimental 
period, depending on the availability ot natural feed. To avoid sudden changes of 
temperature, salinity, pH, dissolved oxygen etc. due to heat and rainfall, effort were 
made to maintain an ideal water depth of l.Om in grow-out ponds and in the ghers. 
Data collection 
Water quality parameters were measured every day using appropriate methods. 
Sampling for growth study were done fortnightly basis. 
Harvesting and data analysis 
After attaining marketable size shrimp were harvested by total weight were 
recorded. Comparison of treatment mean were carried out using one-way analysis of 
variance followed by testing pair-wise difference using Duncan's Multiple Range Test 
(Gomez and Gomez 1984) to determine differences in means (P<0.05). 
Economic evaluation 
An economic analysis was performed Production cost and gross benefit were 
estimated on the basis of whole sale market price of shrimp and inputs during the 
experimental period. 
138 
Stocking densitlj for environmental-friendly shrimp farming 
Results 
The post larvae stocked at two different stocking densities in demo-pond were 
acclimated mostly within 2 hours but depending upon the salinity variation the time 
varied accordingly in farmers gher. The fortnightly growth performance by length 
and weight of two stocking densities of T1 and T2 are presented in Tables 1 and 2 
respectively. During the experimental period growth trend of shrimp under both the 
treatments in the demo-pond were similar. But sluggish growth were noted during 
the whole experimental period. The final growth of T1 and T2 in demo-pond were 
recorded 25.21g and 42.79g, respectively. The weight gain, survival rate and 
production performance are shown in table 3 and 4 respectively. The mean value of 
survival rate, production, weight gain and culture period of demo-pond and local 
farmer's gher in T1 and T2 are presented in Table 3. The culture period of T1 required 
143 days whereas in T2 took 149 days. The production of T2 was (299.01 kg/ha) higher 
than T1 (231.24 kg/ha). The mean weight gain and survival rate of both treatment 
were found almost similar. 
Table 1. Fortnightly growth performance of P. monodon of T1 during the experimental period 
Fortnight 
Pond /Gher 1 2 3 4 5 6 7 8 9 10 
Demo~ond 1.1 4.3 8.1 16.1- 17.3 18.5 19.4 20.1 21.5 25.2 
Farmers gher 
Gher 1 1.2 4.2 7.4 9.5 12.4 15.5 16.7 19.8 22.6 23.4 
Gher2 1.3 4.5 7.5 9.4 12.2 17.6 20.6 23.5 25.3 26.5 
Gher3 1.3 4.3 8.2 16.5 22.4 25.3 29.5 33.6 39.5 42.0 
Gher4 1.2 4.5 8.1 12.2 14.1 16.3 17.4 19.4 21.5 22.2 
Gher5 1.4 4.3 8.5 12.5 17.5 22.5 26.1 29.5 32.5 34.0 
Mean weight 1.28 4.36 7.94 12.02 15.72 19.44 22.06 25.16 28.28 29.63 
Table 2. Fortnightly growth performance of P. monodon of T2 
Fortnight 
Pond /Gher 1 2 3 4 5 6 7 8 9 10 
Demo pond 1.2 4.1 8.3 14.3 20.1 26.0 35.7 37.2 38.3 42.8 
Farmers gher 
Gher 1 1.3 4.0 8.2 12.1 14.3 16.2 17.5 19.4 21.6 22.0 
Gher2 1.2 3.9 7.5 11.3 14.5 17.5 18.2 19.3 20.5 21.0 
Gher3 1.3 4.2 8.1 11.5 16.3 22.5 27.1 29.5 31.3 32.0 
Gher4 1.4 9.3 8.3 12.4 16.5 22.1 26.5 30.5 33.2 35.0 
Gher5 1.2 4.3 8.0 12.2 13.8 16.5 17.2 19.3 25.1 26.0 
Mean weight 1.2 5.1 8.0 11.9 15.0 18.9 21.3 23.6 26.3 27.2 
139 
P.K. Roy et al. 
Table 3. Growth, survival rate and production performance of shrimp in two treatments 
Treatments Weight gain 
(g) 
28.89 
29.88 
3.23 
Survival rate 
(%) 
40.67 
39.33 
2.95 
Production 
(kg/ha) 
231.24 
299.01 
38.45 
Culture period 
(days) 
143 
149 
2.11 
SE*= Standard error of treatment mean, calculated from residual mean square in the analysis of variance. 
Water quality parameters like salinity, water depth, temperature, pH, oxygen 
and transparency were monitored fortnightly from each experimental ·pond. The 
recorded values of each parameters throughout the experimental period are 
presented in Table 4. 
Table 4. Physico-chemical parameters of the water of the cultured ponds during the experimental period 
Treatments 
Pond I Gher 
T1 (Demo pond) 
Farmers gher 
Gherno. 1 
Gherno. 2 
Gherno. 3 
Gherno. 4 
Gherno. 5 
T2 (Demo pond) 
Farmers gher 
140 
Salinity 
(ppt.) 
1 
18-7 
17-5 
17-4 
16-6 
18-7 
17-3 
18-6 
Depth of 
water (m) 
2 
0.7-1.0 
0.4-0.8 
0.5-0.7 
0.6-0.9 
0.5-0.8 
0.6-0.9 
0.7-1.0 
Parameters 
Temperature 
("C) 
Water Air 
3 
25-34 
25-33 
25-32 
26-32 
26-32 
26-32 
25-33 
4 
26.33 
26-32 
25-33 
25-32 
26-33 
25-32 
25-32 
pH 
5 
8.8-9.2 
8.5-9.1 
8.4-8.9 
8.2-9.2 
8.7-9.4 
8.1-8.9 
8.8-9.3 
6 
3.8-
7.1 
4.2-
7.2 
4.1-· 
7.3 
3.5-
67 
3.5-
7.2 
3.6-
7.4 
4.7-
8.1 
Transparency 
(em) 
7 
25-40 
31-42 
33-45 
32-44 
34-43 
36-44 
28-36 
Stocking density for environmental-friendly shrimp farming 
Gherno. 1 17-5 0.3-0.8 25-33 25-33 8.6-9.2 4.2- 35-42 
8.1 
Gherno. 2 16-5 0.4-0.8 26-34 26-33 8.1-9.0 4.6- 33-45 
8.4 
Gherno. 3 18-4 0.3-0.7 25-33 26-32 8.1-92 4.4- 33-43 
8.2 
Gherno. 4 17-5 0.4-0.9 26-33 25-33 8.0-9.3 4.1- 34-44 
8.3 
Gherno. 5 19-6 0.5-0.8 26-33 25-33 8.1-9.0 4.5- 35-39 
8.3 
The comparative gross margin analysis of shrimp production between two 
stocking densities are presented in Table 5. The production cost of T1 was 
comparatively lower (27442.00 Tk/ha) than T2 (30442.00 Tk/ha). The major cost item 
during the experiment were seed and land. The seed cost in T1 covered 43.73% of the 
total cost which was comparatively lower than T2 (49.27%). The gross margin of T1 
and T2 were 41360.20 Tk/ha and 56845.80 Tk/ha. The benefit cost ratio of T1 and T2 
were 2.57 and 2.87, respectively. 
Table 5. Gross margin analysis of shrimp production of two stocking densities at Kaligonj 
Items 
No. of ghers 
Average gher size (ha) 
Post larvae stocked/ha 
Production (kg/ha) 
Gross Benefit (Tk/ha) 
Shrimp 
Others weed fish 
Input cost (Tk/ha) 
Land 
Seed (Pis) 
Ploughing 
Lime 
Gate repair 
Inorganic 
Fertilizer (urea and 
TSP) 
Organic manure 
(cowdung) 
Labour cost 
Taka 
7500.00 
12000.00 
250.00 
1235.00 
800.00 
907.00 
250.00 
4000.00 
Tl 
6 
2.75 
20000 
231.24 
68802.20 
64747.20 
4055.00 
% 
27.33 
43.73 
0.91 
4.50 
2.92 
3.31 
0.91 
14.58 
T2 
6 
2.35 
25000 
299.01 
87287.80 
83722.80 
3565.00 
Taka % 
7500.00 24.64 
15000.00 49.27 
250.00 0.82 
1235.00 4.06 
800.00 2.63 
907.00 2.98 
250.00 0.82 
4000.00 13.14 
141 
P.K. Roy et al. 
Others 500.00 1.82 500.00 1.64 
Production cost (Tk.) 27442.00 30442.00 
Gross margin (Tklha) 41360.20 56845.80 
Gross margin as % of 150.72 186.74 
production cost 
Benefit cost ratio 2.57 2.87 
Discussion 
Data revealed that higher production (299.01 kg/ha) was obtained from the pond 
stocked with 2.5 pls/m2 without significant variation in average survival rate, weight 
gain and production between two stocking densities whereas the variation were 
found significant for demo-pond. Similar observation also reported by Tiro et al. 
(1986) whereas the production rate obtained was 317 kg/ha/ crop. The higher 
production with low stocking rate, support the findings of Kungvankij et al. (1986). 
The production obtained through improved traditional shrimp farming, as reported 
by the authors are almost similar to the present findings and which is more than two 
times than the traditional shrimp production rate (80-130 kg/ha/crop). For both the 
treatments a direct relationship between stocking density and mortality rate were 
observed that confirmed the findings of Chien and Ray (1990). Lower average 
production obtained from the ponds of T1 is in disagreement with the findings of 
Chien and Ray (1990) which might be due to low water depth in that ponds resulting 
an eutrophication thus pave the way of huge algal bloom. And on the other hand fish 
excretions and other organic metabolites in bottom sediment can also resulted in the 
degradation of the water qualities and retarded the normal shrimp growth (Shilo and 
Rimon 1982). 
The wide range of fluctuation of temperature from 25-34oC and transparency 
level from 25-44cm were affected the growth of P. monodon mostly in farmer's gher. 
The result showed that the growth rate of the shrimp was very low or stunted after 
90 days of culture period. This might because of the sudden decline in salinity level 
up to 4 ppt. 
The study demonstrates that in improved extensive method growth of P. 
monodon does not effect even in comparatively slight high stocking density if the 
management system is efficient. The growth performance of shrimp in this 
experiment was 40.67g in 143 days is comparable to that obtained from the grow-out 
pond which was 33-36g in 130 days (Kunguan et al. 1990). 
The present study revealed that environmentally friendly management practice 
may affect profitability of the farms. In south-west part of Bangladesh the most 
important consequences observed for deteriorated environment are presence of 
opportunistic pathogens in the pond water those become active in a favorable 
environmental condition because of poor management during culture operation and 
introduction of other harmful pathogens due to intensification of culture. Low 
production in traditional system also involves low survival of seed because of 
142 
Stocking densitt; for environmental-friendly shrimp farming 
unavailability of food materials and improper acclimatization during release to 
culture pond and entrance of predators with unscreened tidal water those fed in the 
gher. To keep at friendly environment for shrimp culture, maintenance of proper 
culture time is of paramount importance, because culture period of shrimp has 
specific nature that supports optimum production, which is a function of the 
prevailing physico-chemical and biological factors. Timely culture and interaction of 
water quality parameters that attributed to positive impact and efficient management 
of farming aspects were found to play a vital role in keeping the culture environment 
suitable. The study also indicate that greatest economic impact would be achieved by 
improving revenue-determining factors (shrimp density, growth rate, survival and 
market value) rather than intensification. 
Conclusions 
Considering the technicat economical and environmental aspects, the improved 
extension method may be considered for viable for increasing the present average 
production rate of Bangladesh by more than 100 percent. Study also suggest that 
higher rate of production through improved method of shrimp farming with low 
stocking rate can be achieved by efficient management of the farm. 
References 
Bangladesh Bureau of Statistics, 1996. Annual Report, published by Government of the 
Peoples Republic of Bangladesh. 
Chien Yew-hu and Why-Ming Ray, 1990. The effects of stocking density and presence of 
sediment on the survival and growth of tiger prawn, Penaeus monodon fry. In: The second 
Asian Fisheries Forum (eds. R. Hirano and Hanyu). Asian Fisheries Society, Manila, 
Philippines. 991pp. 
Gomez, K.A. and A.A. Gomez, 1984. Statistical procedures for Agricultural Research. 2nd ed. 
John Wily and Sons. 679 pp. 
Kungvankij, P., J.B. Pudadera, B.L. Torp, O.I. Potestas and E. T. Chua, 1986. An improved 
traditional shrimp culture technique for increasing pond yield. NACA Technical Ser., 
Bangkok, Thailand, 5: 14 pp. 
Kungvankij P., S. Weshasit, S. Kongkeo and S. Summawuthi, 1990. Recent pond design, 
construction, and management strategy for shrimp farming in acid sulfate soil in 
Thailand. In: The second Asian Fisheries Forum (eds. R. Hirano and Hanyu). Asian 
Fisheries Sodety, Manila, Philippines. 991 pp. 
Rackowe, R., H. Branstetter, D. King and G. Kitson, 1983. The International market for shrimp. 
ADB/FAO INFOFISH Market Studies, 3: 79 pp. 
Shilo, M. and A. Rimon, 1982. Factors which affect the intensification. of fish breeding in Israel, 
II. Ammonia transformation in intensive fish ponds. Bamidgeh, 34(3): 101-114. 
Tiro, L.B., J.B. Pudadera, O.I. Potestas and P. Kungvankij, 1986. Intensification techniques in 
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(Manuscript received 28 October 1997) 
143 


Optimization of stocking density for environmental-friendly improved extensive shrimp farming system in south-west part of Bangladesh

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Optimization of stocking density for environmental-friendly improved extensive shrimp farming system in south-west part of Bangladesh

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