Effect of Lates calcarifer seed stocking on the survival and production of Indian major carps reared in a freshwater coastal pond in Konkan region

The experiment indicated feasibility of culturing Indian major carps seed with Lates calcarifer, if the size of Indian major carps is larger. In the present investigation the average growths of Catla catla, Labeo rohita and Cirrhinus mrigala are recorded as 1193, 1120 and 821 g, respectively, during the year 1997-98, 1998-99 and 1999-2000 in 7.5 months. Complete harvesting of L. calcarifer is essential before stocking of new seed. The average growth of L. calcarifer was recorded as about 670 g during the above period. About 5000 numbers of Indian major carps fry per hectare can be stocked under the present culture system

Aquacultura de mexilhão marinho Perna-perna (L.)

The Mozambican experimental project on mussel culture began in 1977 to promote cheap food production with high protein value for domestic market. The species Perna perna (L.) has been selected due to its abundance, sustainable culture processes and better yields.

A mixed culture trail of mud crab (Scylla serrata Forskal) with tilapia ( Oreocromis niloticus L.)

A ten-month study on mixed culture of mud crab Scylla serrata with tilapia (Oreochromis niloticus) was performed in brackish water earthen ponds using live tilapia fry as the only feed for crab. The monthly growth rate varied from 9.07-19.llg among four treatments. Treatment T 1, cw: 0.68cm (±0.72) and bw: 19.11 gm (±12.97) showed highest performance which was followed by T 3, cw: 0.62cm (±0.60) and bw: 13.42 gm (±10.51), T4, cw: 0.65cm (±0.64) and bw: 13.20 gm (±9.89) and T2, cw: 0.36cm (± 0.25) and bw: 9.07 gm (±8.05). Highest survivability of crabs was also recorded in T 1 (21.5%) which was followed by T 2 (15.65%), T4 (14.95%) and T 3 (14.15%). In terms of survivability, significant differences (p<0.05) were observed among the treatments whereas these were recorded as insignificant difference (p<0.05) in final weight, weight gain and production of crabs and tilapia. Mixed culture of mud crab with tilapia could make more rewarding than crab monoculture but the study suggests that only tilapia fry can not fulfill the feed requirement of crabs in respects of survivability, final body weight and weight gain. Besides, existed salinity level of 4-12 ppt during experimental period might be the another key factor for low survivability and weight gain.

Over-wintering performance of mixed sex and monosex tilapia (Oreochromis niloticus L.) in Bangladesh

An experiment was conducted for six months in 6 experimental ponds (each size 80 of m2) to assess the over-wintering performance between mixed sex and monosex tilapia, Oreochromis niloticus. The experiment was carried out with two treatments each with three replicates. In the first treatment (T1), mixed sex tilapia were stocked in 3 ponds with a mean initial of 4.80±0.18 g. In the second treatment (T2), monosex tilapia were stocked in another 3 ponds with a mean initial weight of 4.81 ±0.20 g. Each pond was stocked with 250 fingerlings. Fish were fed at the rate of 6% of fish body weight at the beginning. The feeding rate was gradually reduced to 2% for the third month and finally increased to 3% for rest of the period. Water quality was monitored fortnightly and the ranges were: temperature17.86-29.10°C, dissolved oxygen 4.25-6.10 mg/1, pH 6.97-7.20 and transparency 24.10-36.50 cm. After 6 months of rearing monosex tilapia attained a significantly (pproduction of monosex tilapia (3723.10 kg/ha) was about 32% higher than that of mixed sex tilapia (2776.28 kg/ha). The net profit/ha generated from the 6 months culture period was calculated as Tk. 43,311.45 and. 69,277.32/- for mixed sex and monosex tilapia respectively. The results of the present study suggested that it is possible to successfully culture tilapia during the winter period and the culture of monosex tilapia is more profitable due to its higher growth rate than that of mixesex tilapia.

Seasonal fluctuation in primary production in relation to the physicochemical parameters of two weed-infested ponds of Kalyani, West Bengal

Kalyani lake (P sub(1)), a weed infested recreational water body and a weed chocked derelict water body (P sub(2)) in the heart of Kalyani city of West Bengal were studied for a period of one year for their primary productivity and other physicochemical parameters. Very low primary productivity (GPP=360-1237mg C m super(-2) d super(-1); NPP=157-787 mg C m super(-2) d super(-1)) was recorded in P sub(2) in spite of having a high concentration of nutrients (PO sub(4)–P=0.052-0.260mg l super(- 1); NO sub(3)-N=0.110-0.412mg l super(-1)). On the other hand, moderate primary productivity (GPP=1687-3195mg C m super(-2) d super(-1); NPP=900-2700mg C m super(-2) d super(-1)) was found in P sub(1) with comparatively low range of nutrients (P0 sub(4)-P =0.010-0.058mg l super(-1); NO sub(3)-N=0.032-0.118mg l super(-1)). After studying the other physicochemical parameters (temperature, transparency, dissolved oxygen, free carbon dioxide, pH, alkalinity and macrophytic biomass), it was found that the overall hydro-biological conditions of the weed-chocked derelict water body (P sub(2)) is not congenial for biological production as compared to Kalyani Lake (P sub(1)). Kalyani Lake may be used for fish culture with proper management practices.

Seed production and culture techniques of climbing perch, Anabas testudineus

Six treatments each with 12 replications designed to optimize the dose of inducing agent PG to achieve fertilization and hatching success of climbing perch, Anabas testudineus were tested. The females were given single injection of 7-12 mg PG/kg body weight and the males were given 4 mg PG/kg body weight. Fertilization and hatching rate varied from 67±4.55% to 66±3.0% and 59±4.88% to 57±6.21% for the doses of 10, 11 and 12 mg PG/kg of body weight, respectively. The hormone dose had significant (P<0.05) effect on fertilization and hatching. Six mini shallow cisterns (570 cm x 105 cm) were used to investigate the efficacy of zooplankton and Artemia nauplii as feed for spawn rearing. Three-day old spawns were stocked in six mini shallow cisterns at a stocking density of 100 individuals/L of water. Two treatments each with three replications were used to develop culture technique of the climbing perch. In case of treatment-1, the spawns were fed with Artemia nauplii three times daily, while in treatment-2, zooplankton were used as feed in the same manner as in treatment-1. After 14 days of rearing, mean final weight of the fry of treatments-1 and 2 were 95.55±6.71 and 57.69±5.40 mg, respectively. In treatment-1, spawn fed with Artemia nauplii showed significantly (P<0.05) higher mean weight than the spawn fed with zooplankton (treatment 2).

Effect of low cost feed on the production of walking catfish, Clarias batrachus in farmer's ponds

A feeding trial was conducted for six months in farmer's ponds to assess the performance of BFRI formulated catfish feed on the growth and survival of Clarias batrachus (L.). Nine interested farmers and their ponds (size range: 10-15 dec) in the Barera union of Mymensingh Sadar were selected. The ponds were divided into 3 treatments each with 3 replications. Among the three treatment diets, two diets - traditional (F1) and BFRI formulated (F3) were prepared by using low cost agro-based locally available ingredients and the commercial diets was Saudi-Bangla Grower-1 (F2). The diets were designed as F1, F2 and F3 for traditional (20.40% protein), Commercial (31% protein) and BFRI formulated (30.44% protein) diets respectively. The fingerlings of catfish (7.3 g) were collected from local fish vendors and stocked at the rate of 100/dec. Feeding rates were adjusted by weight after fortnightly sampling of fish. Feeding rate were 10 and 8% of the total body weight respectively for 1st, 2nd month and 5% for the rest of the experimental period. The range of some selected water quality parameters were as follows: dissolved oxygen 4.0 - 7.4 mg/l, temperature 24.0°- 33.9°C, pH 6.8 - 8.00, and transparency 17.0 - 32.00 cm. Which showed suitability of the ponds for rearing fish. At the end of the experiment, significantly highest gain (p<0.05) in weight (1210.96% ±87) and lowest gain in weight (865.25% ±90) were observed in the group of fish fed on diets F3 and F1 respectively. However, no significant differences in growth (p>0.05) was observed in fish fed on commercial diet (F2) and BFRI formulated diet (F3). The FCR value ranged between 2.00 and 2.80 with the traditional diet (F1) showing significantly lower FCR. The total production of fish ranged between 1398.08 and 2145.34 kg/ha with F3 diet resulting in the highest production and net profit. A simple economic analysis showed that fish fed with BFRI formulated (F3) diet resulted in the highest net profit in farmer's pond.

Effect of stocking density on growth and yield of GIFT tilapia under rice-fish production system

The study was conducted at the Central Experimental Station, Philippine Rice Research Institute, Maligaya, Science City of Munoz, Nueva Ecija, Philippines during the wet season to determine the suitable stocking density(s) for better growth and yield of fish under rice-fish production systems. Recovery rate of GIFT tilapia in different stocking densities ranged from 75.74 to 83.47%. Among different treatments, rice +5,000 fingerlings/ha and rice +10,000 fingerlings/ha resulted in the highest recovery rate of 83.33% and 83.47%, respectively. The lowest recovery rate of 75.75% was obtained from rice +20,000 fingerlings/ha, but similar to that was obtained (78.56%) from rice +15,000 fingerlings/ha. Significantly higher rate of gain in body weight and that of specific growth rate were recorded in the treatment from rice +5,000 fingerlings/ha, while other treatments resulted in similar absolute and specific growth rate. Fish yield increased significantly with relatively higher stocking densities, but higher densities produced maximum number of smaller fishes and also lower recovery rate.

Impacts of fish sanctuaries on the production and diversity of plankton on beels of haor region in Bangladesh

The experiment was carried out to study the impacts of fish sanctuaries on the production and diversity of plankton in beels of haor region at Mithamain Upazila of Kishoreganj district in Bangladesh during July 2004 to June 2005. A total of 75 (60 phyto and 15 zooplankton) and 74 (59 phyto and 15 zooplankton) genera of plankton were recorded in T-1 and T-2 (with sanctuary) respectively while only 50 (39 phyto and 11 zooplankton) genera were obtained in T-3 (control). Chlorophyceae and Copepoda were the most dominant group of phytoplankton and zooplankton respectively in all the treatments. The total phytoplankton numbers were found to range from 5472 to 35,833 cells/l and 5250 to 40,472 cells/l and total zooplankton from 667 to 1722 cells/l and 611 to 1667 cells/l in T-1 and T-2 respectively in sanctuary sites whereas the ranges of phytoplankton and zooplankton in the control site were 1778 to 29,333 cells/l and 56 to 1056 cells/l respectively. The maximum phytoplankton and zooplankton were recorded during winter season in all the treatments. The ranges of total plankton were 6194 to 37,500 cells/l, 6028 to 41,806 cells/l and 1889 to 29,444 cells/l in T-1, T-2 and T-3 respectively. The phytoplankton, zooplankton and total plankton recorded in treatments with sanctuary were significantly higher (p<0.5) than the treatment without sanctuary (control) indicating positive impacts of sanctuaries on the production of plankton. Between two treatments of fish sanctuaries the total plankton populations were comparatively higher in T-2 than T-1.

Impact of common carp, Cyprinus carpio (L.) and Nile tilapia, Oreochromis niloticus (L.) on arthropods population, zoobenthos and weeds in rice-fish culture

An experiment was carried out in the fields of the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, Bangladesh to determine the impact of common carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) culture on arthropod population, zoobenthos and weeds of rice field. The treatments were: (1) rice combined with mono sex tilapia, (2) rice combined with common carp, (3) rice combined with a mixed culture of mono sex tilapia and common carp and (4) rice alone. It was observed that tilapia significantly reduced the number of arthropods, green leafhoppers and white leafhoppers in the rice-fish production systems. Benthos analysis revealed significant effects of fish culture on the abundance of molluscs, oligochaete worms and chironomid larvae. Lowest number of benthos was obtained in the treatments with common carp and significant reduction of the weed biomass was observed, especially in the tilapia containing plots. Based on the results of the study it can be suggested that common carp may play an important role in controlling of benthic organisms, while tilapia might be more effective to control terrestrial arthropods and weeds.

Diversity, abundance distribution and secondary production of intertidal and subtidal benthic macrofauna of Bushehr Province with emphasis on annelida groups

The present investigation was undertaken to establish a reference situation for future use, to identify temporal and spatial composition of macrofauna and estimate some ecological indices in the sub tidal waters along the Bushehr coastal waters in Persian Gulf. Six transects were selected including Genaveh, Farakeh, Shif, Bandargah, Rostami and Asalouyeh, at each transect 3 station were sampled in depths of zero, 5 and 10 metres. Sampling was seasonally carried out by a VAN VEEN grab 0.0225 m2, during summer 2008 until spring 2009. Samples were wet sieved immediately using 0.5 mm mesh size sieves and sediment retained in the sieve was preserved in 4% buffered formalin solution. Macrofauna specimen were separated from the sediments using decantation and elutriation methods, enumerated and identified up to the Genus level. Environmental factors such as temperature. pH, and salinity were recorded in field using sensitive probs and refractometer (for salinity) and also sediment samples were taken for TOM and grain size analysis in all the stations. 5611 specimens belonging to 66 genera were collected during the present study. Polychaetes were dominant both in terms of genus number (31) and relative abundance (74 % of total macrofaunal abundance). The other dominant groups were Artheropoda, (16.1%), Molusca (2.8%), Echinodermata (1.29%) and others including Nematoda, Nemertina, Echiura and Turbellaria (5.8%). Thirty one Genera belong of 27 families of polychaeta, one genus and family of Subphylum Chlicerata,19 genera belong to 14 families of Crustacea, 8 genera belong to 6 families of Molusca, were indentified in the studied region. 1 family (Polygordidae) and 3 genera (Flabeligera, Pilargis and Polygordius) of Polychaeta, 1 family (Nymphonidae) and genus (Nymphon) of Chelicerata, 1 Family (Nematoplanidae) and genus (Nematoplana) of Turbellaria, were identified for the first time in Persian Gulf area. The result indicated that macrofauna organism have strong relationship with the grain size characteristics of the sediments they inhabit. The most surface deposit feeder specimens such as Prionospio and Cossura were found in zero meters depth of Genaveh, Farakeh, Bandargah, Rostami and Asalouyeh stations with sandy substratum, however the most burrowing deposit feeder and scavenger specimens such as Capitella and Petaloproctus were collected in 5 and 10 meter depths of stations with silty–clay substratum. The annual mean abundance, Shanon- weiner diversity and evenness of macrofauna were estimated1152.73 N/ m² , 2.72 and 0.792 respectively .The annual average biomass and secondary production were computed 1.797 gDW m² and 3.594 gDW m² y-1 .The average of water temperature, salinity, pH and oxygen concentration were recorded between 16.37-36.05 °C, 38-42 g/l, 7.89-8.76 and 4.23-8.23 mg/l, respectively during this study in 6 studied region. Among of investigated stations Asalouyeh adjacent of effluent canal of Gas and petrochemical industry sewage and Farakeh regions adjacent the Helleh estuary had the lowets and the highest community indices. The average of diversity and density in 5 meters depth stations with moderate of sand, silt and clay were slightly more than 2 other depths stations, it seems that 5 meters stations are made a transition habitats between 2 sandy and clay habitats, that can be used by 2 groups of surface and borrowing deposit feeders. Based on the data provided in this survey, the temperature variation, sediment texture, TOM, type habitat and manmade factors of Gas and petrochemical industries have had the most effect on the macrofauna community structure in the studied region during sampling periods.

Introducing tilapia (GIFT) with shrimp (Penaues monodon) in brackishwater rice-shrimp system: impact on water quality and production

Mixed rearing of tilapia (Genetically Improved Farmed Tilapia, GIFT) with shrimp (Penaeus monodon) in brackishwater rice-shrimp system was assessed for its impact on dry season's shrimp production. The experiment was conducted in pre-selected farmer's field located at Paikgacha Upazila of Khulna district and designed with three different densities (treatment) of GIFT, viz, 0.3, 0.4 and 0.5/m² with a constant stocking density of shrimp at 3/m². Each treatment had three replications. There had a set of control treatment where GIFT was not stocked. Results of the experiment revealed that tilapia did not exert any significant effect (p>0.05) on the water quality variables, even on survival rate of shrimp (p>0.05) under farm level condition in rice-shrimp rotational system, but a density dependent negative effect (P<0.05) on the growth of shrimp led apparently lower production rate of shrimp. Though tilapia provided the major augment of total production (p<0.05) in the respective treatments than in monoculture of shrimp, but not that of the economic return. However, economic loss due to sudden shrimp crop failure might be partially minimized by the tilapia crop.

Suitability of commercially available Bacillus probiotics on growth, survival and production of black tiger shrimp (Penaeus monodon Fab.)

Different forms of Bacillus probiotics was assessed in the earthen ponds on tiger shrimp (Penaeus monodon) culture. The experiment was designed with three different treatments depending on the mode of application (T1=oral probiotics; T2=spreading probiotics and T3=oral+ spreading probiotics). The shrimp was cultured for 120 days with the stocking density of 6-PL/m².Oral probiotics in the respective ponds were supplied with feeds. Whereas, spreading probiotics was applied to the pond water during pond preparation at 30, 60 and 90 days of culture period. Results of the experiment revealed that, all forms of Bacillus probiotic had effective role to keep the culture environment friendly in terms of mineralization of organic matter, nitrogen and phosphorus content in bottom sediment; holding of water transparency in a congenial state, increasing the density of planktonic biomass and boosting the THB-Vibrio ratio in water and sediment with insignificance (p>0.05) difference between different treatments. Whilst, spreading form of Bacillus pro biotic showed higher weight gain (27.58±1.18g), survival rate (70.75±8.54%) and production (1167.66±109.62 kg/ha) and expected lower FCR (1.81 ±0.06) values with significant difference (p<0.01) with others methods of application, indicated its superiority in tiger shrimp culture.

Feasibility study of biofuel production from freshwater fern, Azolla sp in Anzali Wetland

Production of bioethanol through acidic and enzymatic hydrolysis of aquatic Azolla sp., as a new source of bio-mass, has been performed, as a means to control increasing growth and reducing undesirable effects of this plant in Anzali lagoon. After sampling, drying and crushing, Azolla was hydrolyzed, using diluted acid and enzyme. Diluted acid hydrolysis was done using both autoclave and a high-pressure system (Batch Synth® Microwave synthesizer). The effects of temperature and time (in autoclave) and concentration of acid (in both) were compared. Cellubrix®, a ommercial cellulase source, was used for enzymatic hydrolysis process. The amounts of reducing sugars, glucose and furfural, released from hydrolyzate, were measured. To produce alcohol, Sacchromyces cerevisiae (to ferment sixcarbon sugars), Zygowilliopsis californica and Pichia stipitis (to ferment five-carbon and sixcarbon sugars) were used. Maximum amounts of glucose (4.83% w/w) and reducing sugars (14.15% w/w) were obtained using acid hydrolysis in autoclave. In the microwave oven, maximum glucose (5.04% w/w) and reducing sugars (13.27 w/w) were obtained at 180 and 200 °C, respectively. Under these conditions, maximum produced furfural was 1.54 g/L. The difference between amounts of furfural obtained from acid hydrolysis of Azolla in microwave oven compared to autoclave was statistically significant. Amounts of alcohol produced and its yields were 3.99 g/L and 33.13% for S. cerevisiae in 48 hours, 3.73 g/L and 30.45% for Pichia stipites in 48 hours, and 3.73 g/L and 30.45% for Z. californica in 24 hours after inoculation, respectively, with significant differences. Statistical comparison of results showed significant differences (P<0.05) in glucose production, at different conditions. Amounts of reducing sugars and glucose increased after optimization of levels of acid, time, and temperature. The overall optimum released sugar and glucose were obtained with 1.67% (w/v) acid using autoclave. Higher temperatures in microwave oven caused a significant increase (P<0.05) in furfural. Furfural severely inhibits fermentation. Hence, regarding the issues of energy consumption and time, amounts of inhibiting substances and sugar production, autoclave is found to be superior to the high temperature and pressure, generated in microwave oven, for hydrolyzing Azolla. Furthermore, given the amounts of Azolla in Anzali lagoon, it may be recommendable to use this plant as a biomass resource.

Assessing potential of production in Lake Choghakhor

Phytoplankton productivity is the common and important factor being considered in determining the overall status of a given body of water. This is because they are found at the base of an energy or food chain, being the basic source of primary food in a given aquatic system. Hence, information on their contribution is essential in indicating how much biomass energy will be available to all other living resources in the system. Though the primary productivity of shallow lakes is characterized by mixed populations of phytoplankton and submersed aquatic vegetation in the open water. Lake Choghakhor, is a shallow lake, located in Chaharmahal-Bakhtiyari Province. This lake is the most important ecosystem in the region especially for waterfowl populations, has a recreational value and supports tourism and fisheries. During last decade Choghakhor has been influenced by some man-made impacts such as water level fluctuation, agricultural discharge and fish (Cyprinids) introduction causing a serious problem in its trophic states. So water quality for physical, chemical and biological was monitored in five sampling stations, from April 2003 to March 2004. As biological parameters we studied phytoplankton, epiphytic algae, and zooplankton and macrobenthose community structure. Chlorophyll a content for phytoplankton and epiphytes was measured to estimate production of these groups (biomass over time). Also we determined biomasses of submersed macrophytes and macrobenthose and primary production of phytoplankton (dark and light bottles technique) to estimate fish production. The results of this study showed Lake Choghakhor did not undergo stable thermal and oxygen stratification, and the lake water was mixed throughout the study (the lake mixing regime is polymictic). Now submerged plants especially Myriophyllum spicatum has covered almost the entire lake and dense macrophyte beds (Polygonom amphibium), located on the east southern end of the lake appear to act as a sink for these nutrients. Lake Choghakhor appeared to be in a macrophyte dominated clear water state with low TP (annual mean: 24± 15μg.l-1) and chlorophyll a (annual mean: 3±1.28μg.l-1) concentrations and very high Secchi depth. The grazing pressure of dominant pelagic filtering zooplankton Daphnia longespina did not seem to be significant in determining the low phytoplankton crop expressed as chlorophyll a. We expect that sequestering of nutrients by submerged plants and associated epiphytes are the dominant stabilizing mechanisms suppressing the phytoplankton crop of Lake Choghakhor.