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by
S. Dewan |
Total Records (
3 ) for
S. Dewan |
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A. K. Yousuf Haroon
,
A. Razzaque
,
S. Dewan
,
S. M. Nurul Amin
and
S. L. Rahman
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Estimated fishing mortality and exploitation values for L. rohita and
L. calbasu indicated that their stocks are under heavy fishing
pressure. Exploitation values were much higher than the optimum level
of 0.5 and remarkably higher than the Emax values. Mean annual
catch of L. rohita in 1999 and L. calbasu in both 1998 and
1999 were much higher than their estimated maximum sustainable yield (MSY).
Whereas the exploitation values for L. gonius were below the optimum
level in 1998 and just at optimum in 1999. The stock of L. gonius is
almost under optimum fishing level. Mean annual catch of L. gonius
were lower or almost equal to its estimated MSY value in both the
years. The Lc/L and M/K values also confirm the above conclusion
for L. rohita, L. calbasu and L. gonius. |
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M.J. Alam
,
S. Dewan
,
M.R. Rahman
,
M. Kunda
,
M. Kunda
,
M.A. Khaleque
and
M.A. Kader
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The experiment was carried out simultaneously to compare the growth performance of Amblypharyngodon mola in rice fish culture system with Barbodes gonionotus and cyprinus carpio in farmer`s rice fields near to Bangladesh Agricultural University campus, Mymensingh for a period of 113 days from 12th August to 3rd December, 2002. Three treatments viz., T1 with A. mola and B. gonionotus, T2 with A. mola and C. carpio and T3 as control (without fish) were used in this study. Each treatment was provided with three replications. All the treatments were fertilized with urea (200 kg ha-1), TSP (150 kg ha-1) and MP (75 kg ha-1). With respect to cultural suitability, A. mola showed comparatively high growth rate and survival rate when it was stocked with C. carpio than with B. gonionotus. Among the three species A. mola showed the lowest growth rate and C. carpio showed the highest growth rate by average, net and percentage of increase. The production of fish were also recorded higher (576.27 kg ha-1) in the treatments stocked with A. mola and C. carpio than (298.91 kg ha-1) the treatment stocked with A. mola and B. gonionotus. However, the growth rate and survival rate of A. mola were always higher in treatment T1. Significantly (P<0.01) higher yield of grain and straw were obtained in the treatments with fish than without fish and they were found to increase over the control by 15.88-19.34% for grain and 12.78-15.34% for straw. The initial values (before rice transplantation) of soil pH, organic matter, total nitrogen, phosphorus and potassium contents did not show any significant difference among the treatments in most cases, but the final values (after harvest of rice and fish) of the same were recorded significantly higher in the treatments with fish than that of control (without fish) in most of the cases except pH. |
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M.R. Mondol
,
S. Dewan
,
M.A Hossain
,
M. Asaduzzaman
,
M.A. Islam
and
U.A. Rozario
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In the present experiment the fingerlings of Puntius gonionotus (Thai Sarpunti) were stocked in the experimental rice field plot of Agronomy Field Laboratory, Bangladesh Agricultural University, to study their food and feeding habits in rice field. The fingerlings of this fish were stocked after 20 days of transplanting rice seedlings and the samplings of fishes were done once in every month from June to August. The gut contents of fishes were analysed by the numerical method and percentage of frequency of occurrence method. The water quality parameters such as temperature, Dissolved Oxygen (DO), pH, total alkalinity, chlorophyll-a, nitrate-nitrogen and phosphate-phosphorus showed monthly variations and they were within productive range. A total of 37 genera of phytoplankton belonging to Chlorophyceae, Euglenophyceae, Cyanophyceae and Bacillariophyceae were recorded in the water of the experimental plot of rice fields and in zooplankton population a total of 13 genera belonging to Rotifera, Cladocera and Copepoda were recorded. Among the 4 groups of phytoplankton Chlorophyceae was the most dominant group and Euglenophyceae was the least dominant group and in zooplankton Rotifera was recorded as the most dominant group and Cladocera as the least dominant group. However among the plankton population, phytoplankton was recorded highly dominant over zooplankton in the water of rice field. Among the genera of phytoplankton Fragilaria, Navicula, Surirella, Chlorella, Chrysococcus, Scenedesmus, Ulothrix, Euglena, Cyclotella and Oscillatoria and among the genera of zooplankton Brachionus, Cyclops, Asplanchna and Nauplius were dominant in water of the plot. The total number of genera of phytoplankton recorded in the gut contents of P. gonionotus were 36 and that of the genera of zooplankton recororded were 6. Among the 4 groups of phytoplankton Bacillariaophyceae was the most dominant and preferred group. With respect to zooplankton. P. gonionotus showed very less preferance on them. Among the genera of phytoplankton the relatively more preferred genera were Navicula, Closterium, Fragilaria, Chrysococcus, Oscillatoria, Tabellaria, Scenedesmus, Ulthrix and Aphanizomenon. P. gonionotus showed very less preference on the genera of zooplankton. P. gonionotus may be regarded as planktivores feeding mostly on phytoplankton. |
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