Studies on selected biological parameters off Mithapur (Gujarat)

The biological characteristics off Mithapur, India, indicated fairly high productivity in terms of macrobenthos and phytoplankton pigment concentration. The area sustained low standing stock of zooplankton. The overall biological productivity of plankton and macrobenthos indicated 30-90% reduction from the premonsoon to postmonsoon period. This decline in the standing stock of plankton and benthos was coinciding with the peak fishing season of the area.

Selected trace metal concentration in bottom water and sediments of Kyoga basin lakes, and its potential to aquatic pollution

Although other research studies on areas such as the physical-chemical, nutrients and phytoplankton status of Lake Kyoga systems have been given a lot of attention (e.g. Mungoma 1988 and NaFIRRI 2006), efforts to determine the pollution status of this system, especially by heavy metals as one of the worldwide emerging environmental problems, is still limited. Many trace metals are regarded as serious pollutants of aquatic ecosystems because of their persistence, toxicity and ability to be incorporated into food chains (Mwamburi J., and Nathan O.F., 1997). Given the rapid human population growth and the associated economic activities both within the rural and urban areas in Uganda, such fish production systems are becoming very prone to various kinds of pollution including that by heavy metals. Anthropogenic factors such deforestation, use of chemicals and dumping of metallic products, spillages of fuels from outboard engines and many others and or natural processes involving atmospheric deposition by wind or rain, surface run-offs and streams flows from the catchment introduces heavy metals into the lake environment,.

Observation on some of the environmental parameters of selected shrimp farms in Khulna, Bangladesh

In recent years, the ecological degradation, loss of technological sustenance and other multidimensional consequences caused by shrimp farming have made the experts and authorities bound to rethink about the development of the industry. The present study describes the water and sediment quality, and culture and management techniques in five selected shrimp farms at Paikgacha, Khulna throughout a production cycle from March to September 1997. The water quality parameters were found to be more or less suitable throughout the cycle. The concentration of the limiting major nutrients such as nitrogen and phosphorus and minor nutrients such as calcium and magnesium were satisfactorily high, concentrations of the organic matter content were also high. Remarkable negative correlation of shrimp production with secchi depth was observed among the farms. Production per cycle ranged between 273 kg/ha and as low as 63 kg/ha.

An empirical study on income and efficiency of pond fish and nursery fish production in some selected areas of Pabna, Bangladesh

The study was designed to determine the costs, returns and relative profitability of pond fish and nursery fish production. In order to attain this objective, a total of 70 producers: 35 producing pond fish and 35 producing nursery fish were selected on the basis of purposive random sampling technique from 6 villages under two Upazilas (Sujanagar and Santhia) of Pabna district. It was estimated that per hectare per year gross cost of pond fish production was Tk 65,918 while gross return and net return were Tk 91,707 and Tk 25,789 respectively. Per hectare per year gross cost of nursery fish production was Tk 87,489 while gross return and net return were Tk 1,39,272 and Tk 51,783 respectively. The findings revealed that nursery fish production was more profitable than pond fish production. Cobb-Douglas production function was applied to realize the specific effect of the factors on pond fish and nursery fish production. It was observed that most of the included variables had significant impact on pond fish and nursery fish production. Out of five variables included in the function, all the variables had positive impact on return from pond fish production but stock value of pond, material cost and pond area had positive impact on return from nursery fish production.

Economics of pond fish culture in some selected areas of Bangladesh

A simple costs and return analysis was done to determine the profitability of pond fish culture in three selected thanas namely Nertakona Sadar, Purbadhala and Kendua under Netrakona district. Cobb-douglas production function model was used to estimate the contribution of key variables to the production process of pond fish culture. It was found that cost of pond fish production was Tk. 10,103/ha/yr and the per hectare fish yield was 943 kgl/yr and the average gross and net return were Tk. 49,515 and Tk. 39,412 respectively. It was found that medium and small farms had the higher yield because of efficient use of production inputs compared to large farms. It was also observed that ownership of pond, number of species and human labour had negative impact on pond fish output, while depth of pond water, farm size, fish seed, fertilizer and artificial feed had significant positive effects on pond fish output.

Observation on some of the environmental parameters and feed quality of selected golda (Macrobrachium rosenbergii) farms in Bangladesh

A study was conducted to ascertain the existing farm water, effluent and feed quality of selected giant freshwater prawn farms from major prawn farming areas (Bagerhat Sadar, Noakhali Sadar and Mymensingh) of Bangladesh during July to November 2005. Water quality parameters such as the mean values of dissolved oxygen, alkalinity, nitrite-nitrogen, phosphate-phosphorus and ammoniacal nitrogen did not show any significantly differences among the farming areas. Whereas significant differences (p < 0.05) were observed in the mean values of temperature, secchi disc visibility, pH and chlorophyll a. However, all the water quality parameters in the farming areas were within the suitable range for prawn culture. There was no significant variation in nutrients concentration of discharged effluent among the prawn farming areas. All of the nutrients measured in effluent water were within the acceptable range and did not seem to pose a direct threat to the recipient environment. The analysed crude protein contents of commercial CP, Quality and Saudi-Bangla prawn feeds were 31.84%, 27.21% and 28.97%, respectively, whereas all analysed farm made feeds were less than 25%. The other nutrients of prawn feeds varied largely with the source of feeds and ingredients used to prepare feed. The annual yield of prawn varied from 320.4 to 512.6 kg/ha (mean 412.3 kg/ha) depending on the management system.

Diversity indices of selected macrobenthos in Karanja Creek (District-Raigad), Maharashtra, west coast of India

The diversity indices can be used as a good measure for studying the effect of industrial pollution because industrial wastes and sewage almost always reduce the diversity of natural systems into which they are discharged. A measurement of diversity often provides a better index of pollution than a direct measurement of pollutants. The assessment of macrobenthos diversity with respect to diversity indices reflects the marine population and habitat disturbance, and also serves as an important indicator of environmental conditions. The present study was designed to investigate the diversity indices of selected macrobenthos at two ecologically distinct locations on the Karanja creek (District - Raigad), Maharashtra, west coast of India. Results on various diversity indices like Index of Frequency (F) or Importance Probability (Pi), Index of Dominance (c), Rarity Index (R), Shannon's Index of General Diversity (H¹) Margaf’s Richness Index (R sub(1)) and Evenness Index (e) did not vary significantly. This demonstrates that at present, Karanja creek harbours varied forms of macrobenthic community showing no effect of human disturbance, but in future, measures must be taken for the protection and conservation of macrobenthic community of the creek.

Economic analysis of carp based culture technologies in selected areas of Bangladesh

Six carp based culture technologies such as, carp-pangas, carp polyculture, carp-golda, pangas monoculture, golda monoculture and nursery have been selected to determine the cost and returns of respective technologies in Bangladesh. The sample farmers selected for these technologies were 55, 100, 65, 50, 51 and 55 respectively and thus the total sample size stood at 376. The study covered 7 districts of Bangladesh, namely, Mymensingh, Bogra, Noakhali, Comilla, Jessore, Khulna and Bagerhat. Both primary and secondary data were used for this study. It was found that farmers used a good number of feeds for the selected technologies and they maintained no standard doses for them. Remarkable differences were found among the prices of different feeds and other inputs used for different technologies in different locations. Prices of all inputs were found to be increasing and this increase was more in recent years compared to previous years. Though all the technologies were found to be profitable, the feed situation was not satisfactory. Except rice polish all the local feeds showed deficit in supply to meet the national demand for the country. If this situation persists and no proper measures are taken to secure the local feed supply, the present development of supplementary feed-based aquaculture would be fully dependent on imported feeds and would not be sustainable in future. This study strongly suggests the corresponding authority to handle the matter with proper attention considering its significant livelihood impact on the economy of the country.

Culture practices of freshwater giant prawn in some selected areas of Mymensingh

A study was conducted to examine the culture practices of freshwater giant prawn, Macrobrachium rosenbergii in some selected areas of Mymensingh. Based on a sample of 100 farmers from three different upazila, namely Phulpur, Gouripur and Ishwargonj in Mymensingh district, 94% of farmers cultured prawn with fish in their pond. Only 6% of farmers cultured prawn, fish and dike crops for higher economic return. The culture period is typically nine months; hatchery produced post-larvae were stocked from May to June and harvested from November to January. Per hectare production of prawn, 375 kg/yr was very low because the farmers followed simple culture method. Most of the farmers made a profit of Tk. 68,403/ha/yr and the major costs incurred were for purchasing prawn seed and feed. The culture of prawn in pond system is technically possible under different conditions though expansion of small-scale prawn farming mainly depends on reduction of production costs. Future targets could be integration of pond prawn culture with other agricultural activities especially dike cropping and rice production in the monsoon.

Shifting rice farming to fish culture in some selected areas of Mymensingh, Bangladesh: the process, conflicts and impacts

The evolutionary process of converting low-lying paddy fields into fish farms and its impact on agrarian communities in some selected areas of Mymensingh district were studied. This study was conducted through participatory rural appraisal (PRA) covering 12 villages from each of selected upazillas viz. Fulpur and Haluaghat of Mymensing [sic] district. A total of 12 PRA sessions were conducted where 90 farmers participated during 29 July to 26 August 2004. It is seen that the use of low-lying paddy fields was mostly confined to Broadcast Aman (B. Aman) rice production until 1960s. With the introduction of modern rice farming technology, the farmers started to produce Boro rice in Rabi season and B. Aman rice in Kharif season. With the passage of time, aquaculture technologies have been evolved and the farmers realized that fish farming is more profitable than rice cultivation, and then they started to utilize their paddy fields for alternate rice-fish farming and rice-cum-fish farming. Now a days, aquaculture based crop production system is in practice in more than 25% of the low-lying paddy fields. Conversion of rice fields in to fish ponds has brought up a change in the livelihood patterns of the rural farmers. The areas where the farmers involved themselves in the new production systems were fingerling collection, transportation and marketing of fry and fingerlings. During 1960s to 1970s, a few people used to culture fish in the permanent ponds for their own consumption, the species produced were rohu, catla, mrigal, ghainna, long whiskered catfish, freshwater shark (boal), snake head (shol) etc. Small fishes like climbing perch, stinging catfish, walking catfish, barb, minnows etc. were available in the rice fields during monsoon season. In 1980s to mid 1990s, some rice fields were converted into fish ponds and the people started to produce fish for commercial purposes. When rice-fish farming became profitable, a large number of people started converting their rice fields in to rice-fish culture ponds. Culture of some exotic fishes like silver carp, tilapia, grass carp, silver barb etc. also started in the paddy fields. Higher income from fish farming contributed positively in improving the housing, sanitation and education system in the study areas. It is seen that the medium and medium high lands were only used for alternate rice fish farming. The net income was high in any fish based cropping system that motivated the farmers to introduce fish based cropping system in the low-lying inland areas. As a result, the regional as well as communal income disparities occurred. However, the extraction of ground water became common during the dry period as the water was used for both rice and fish farming. Mass conversion of paddy fields into rice-fish culture ponds caused water logging in the study areas. In most cases, the participated farmers mentioned that they could be easily benefited by producing fish with T. Aman or only fish during the monsoon season. They agreed that this was an impressive technology to them and they could generate employment opportunities throughout the year. Finally, the social, economic and technical problems which are acting as constraints to rapid expansion of fish production system were reported from the interviewee.

Fish seed production and marketing in some selected areas of Bangladesh

The main objective of the study was to assess the production and marketing system of fish seed and examining the demand for and supply of fry and fingerlings in some selected areas viz. Mymensingh, Netrokona and Tangail in Bangladesh. The present study selected the related stakeholders like 20 Fish Seed Multiplication Farms (FSMF) owners, 80 nursery operators, 20 fry traders and 90 fish farmers who are the beneficiaries and directly involved with the fish seed production and supply chain, and marketing system of fish seed. In case of nursing and rearing fingerlings, only those stakeholders (nurserers and fish farmers) attached with NGOs were selected and the NGOs were GRAMUS, SARA and ORD from Mymensingh and SATU from Tangail district. Data were collected for the period 2004-2005 and most analyses were done by using tables and flow chart to determine production and marketing system of fish seed.

Marketing of small indigenous species of fish (SIS) in three selected fish markets of Mymensingh

A socio-economic survey was conducted round the year in three fish markets at Mymensingh, Bangladesh. The selected markets were categorized as rural market (Sutiakhali market), a peri-urban market (Kamal Ranjeet market, BAU) and an urban market (Notun Bazar market, Mymensingh town). It was learnt from the survey that the availability of Small Indigenous Fish Species (SIS) declined to a great extent over the last few years and at presently many of such fish species are either threatened or at the edge of extinction. The supply of SIS was highest in KR market (37% of total) and more or less similar in Notun Bazar and Sutiakhali fish market (25 and 27% respectively). The total supply of SIS fluctuated from 25% to 35% throughout the year in these markets. About 48 SIS were found in the sampled markets over the survey period. The highest number of species (45) was found in KR market followed by Notun Bazar (42) and Sutiakhali (37) fish markets. During the survey, three critically endangered species namely, schilbid catfish, garua catfish and rita were found in these markets. Beside these, other 11 and 10 species were listed to be endangered and vulnerable respectively. The biodiversity of 21 SIS found in three markets were no threat at all. Three species (guntea loach, Indian glass barb and flying barb) were 'data deficient' as reported by the IUCN Red Book (IUCN-Bangladesh 2000). From the supply point of view small prawn, spotted snakehead, stinging catfish, pool barb, striped dwarf catfish, Gangetic mystus, walking catfish and tank goby were the prominent fish. The least available species found in this survey were lesser spiny eel, barred spiny eel, Gangetic ailia, freshwater garfish, zig-zag eel, flying barb, Ganges river sprat, freshwater river shad and dwarf gourami. The weight of SIS available in Notun bazar was highest and nearly double than other two markets. There was no significant difference recorded in the supply of SIS in Sutiakhali and KR markets. The average monthly SIS supply was 185, 192 and 467 kg in KR, Sutiakhali and Notun Bazar, respectively; therefore, the cumulative average supply was 844 kg per month in three markets. The price of SIS ranged widely from taka 50-450/kg depending on species, location of market, time of purchase and the condition of fish. In general small prawn, ticto barb, dwarf gourami, Gangetic leaffish, and Annandale loach were sold at a lower price (ranged taka 50-100/kg) and these species could be considered at the bottom of the market-price list. Other SIS like walking catfish, climbing parch, butter catfish, cotio and schilbid catfish valued as highest price (ranged taka 150-450/kg). There was no specific marketing chain for SIS in Mymensingh region. The components of marketing channels and their expansion varied with seasons and locations. The general pattern, however, was as this - after buying fish from fish farmer/fishermen, middlemen (locally known as Foria) used to buy fish to wholesale market and sell to the wholesalers. The retailers used to buy fish from wholesaler through auction to the highest bidders. The retailers then send the fish to particular market where the fish reached the consumers. The livelihood strategy of SIS retailers in three fish markets showed that socio-economic constraints such as low income, poor educational background, low economic status and lack of capital are the main constrains [sic]. Most of the retailers proposed that government should control the fish price throughout the year, so that the producers can get reasonable and stable price. Construction of cold storage and preservation facilities at market sites, improvement of road and communication, improvement of physical market facilities and reduction of market chain is essential. Credit facilities, improvement of their standard of living, health and sanitary condition, housing condition, children education and access to drinking water facilities were identified as additional aspects to improve socio-economic condition of SIS retailers.

Adoption, productivity and profitability of rice-fish and fingerling culture in three selected districts of Bangladesh

The study aimed to investigate the productivity and profitability of rice-fish farming. It also determined the factors affecting rice-fish and fingerling production in Bangladesh. Among the total respondents about 55% were involved in rice-fish farming, 37% in pond fish culture and rest 9% in fish nursery. Integrated rice-fish farming contributed about 83% of the annual farm income in Comilla while it was about 20% in both Kishoregonj and Chandpur districts. Among the different farming systems integrated rice-fish culture and rearing fingerlings in the nursery pond were more profitable at the farm level. Farmers earned a net return of Tk. 49,714/ha from integrated fish culture with boro rice while the net return of boro rice-alone was only Tk. 11,179/ha. This indicated that farmer could earn 218% higher net return from integrated rice-fish farming than that of boro rice only farming. Moreover, integrated rice-fish culture also reduced pesticides cost to about 77% and weeding cost to about 51% in boro season. Fingerling nursing earned highest net returns among the three technologies.

Demonstration of some selected aquaculture technologies under farming system research in Jessore and Santahar, Bangladesh

BFRI evolved some selected aquaculture technologies viz. polyculture of carps in perennial ponds, monoculture of short cycled fish species (BFRI super strain) in seasonal ponds and prawn seed production through backyard hatchery system have been demonstrated under Farming System Research (FSR) component in Jessore and Santahar regions. Both polyculture of carps and monoculture of short cycled fish species technologies were tested in farmer's ponds in Kaium Kula village near Jessore town. In polyculture trials, seven species comprising of silver carp (Hypophthalmichthys molirrix), catla (Catla catla), rohu (Labeo rohita), grass carp (Ctenopharyngodon idellus), common carp (Cyprinus carpio), mrigal (Cirrhinus cirrhosus) and silver barb (Barbonymus gonionotus) were stocked @ 9,500 (ratio 6:2:4:2:1:5:5); 10,750 (ratio 6:2:4:2:1:5:5) and 12,000 (ratio 6:2:4:2:1:5:4) fish/ha respectively in ponds of T1, T2 and T3 having three replications of each. The mean highest fish production was 3,148 kg/ha in T3, followed by 2,899 kg/ha in T1 and 2,875 kg/ha in T2. Production of T3 was significantly different (P<0.05) than both T1 and T2, while there was no significant differences (P>0.05) between the production of T1 and T2. In case of trial of short cycled fish species, two treatments were tested: T1 (comprising of BFRI super strain of Nile tilapia, silver carp, common carp and silver barb; ratio 3:5:1:1) and T2 (having only BFRI super strain of Nile tilapia). Stocking density in both the treatments were same (20,000 fish/ha). In this trial average production was higher in T1 (2,743 kg/ha) than that of T2 (2,369 kg/ha) but the production figure in these two treatments was not significantly different (P>0.05). Demonstration of backyard prawn hatchery technology was tested at Santahar region of Bogra district, North-west part of Bangladesh. This hatchery consisted of three main components i) bio-filter, ii) rearing tank unit (chari) and iii) air blower/air pump unit. Plastic drum of 200-250 l capacity and cemented chari of 200-250 l capacity were used as bio-filter and larval rearing containers respectively. A 0.5 hp air blower with 6 aquarium air pump were used to operate the aeration system in the hatchery. Diluted sea water (10-12 ppt) made from brine solution (200-250 ppt) collected from salt-bed was used in the backyard hatchery system of hatching of eggs and rearing of larvae. Rearing of first stage zoea-larvae was reared in three rearing tanks following the stocking densities of 40, 50 and 60/l of water respectively. Production of post-larvae were 20±0.82, 22±1.12 and 28±1.63/liter of water in treatments I, II and III respectively in 38, 40 and 39 days rearing period.

Discriminant analysis of selected variables in the adoption of fish curing

Discriminant functions were worked out for adoption or non-adoption of five improved practices in fish curing. Four variables measured quantitatively formed the basis for discrimination. In four out of five equations, the selected variables were found to discriminate significantly between the adopters and non-adopters.