A preliminary study on the feasibility of using fenced brushparks for fish production in Lake Chilwa, Malawi

A study to investigate the feasibility of using fenced brushparks for fish ranching in Lake Chilwa was conducted for five months at the Kachulu Harbor. In a water depth of 1.4 m enclosures constructed from bamboo sticks embedded in the sediment and surrounded by a 13 mm seine net, were filled with three different subrates (Typha, bamboo, and Sesbania branches) and a no substrate enclosure served as a control. Netting materials contributed 57 per cent towards the total cost (US$ 0.24-0.30/m2) of brushpark contruction. Fish productivity was highest in the Typha, bamboo and control treatments and lowest in the Sesbania treatments. The decomposition of substrates did not affect water quality. The results indicate that enclosed brushparks may be a feasible technology for enhancing fish yields and providing alternative income sources to fisherfolk in small lakes and water bodies.

Management of broodstock and quality control of fish seed in Hungary

Common carp (Cyprinus carpio) breeding has a long tradition in Hungary. However, recent economic changes in Eastern Europe and new developments in aquaculture necessitated the need for ensuring quality of the brood stock used in hatcheries and the legal and institutional frameworks needed to implement the program. In addition to good research and development programs and gene banking, it became essential to establish an appropriate legal framework, organize, coordinate and control breeding activities, and provide financial support. It was a major breakthrough for carp breeding when C.carpio was recognized as one of the cultivated animals in the Animal Breeding Act in 1993. The Carp Breeding Section of the Hungarian Fish Producers Association plays an important role in carp breeding programs. Thirteen breeding farms of the Carp Breeding Section have 24 certified C.carpio varieties. In Hungary, about 80 % of the seed used as stocking for commercial production are from high quality certified breeders.

Application of Marine Protected Areas for Sustainable Production and Marine Biodiversity off Alaska

Fisheries managers have established many marine protected areas (MPA’s) in the Federal and state waters off Alaska to protect ecological structure and function, establish control sites for scientific research studies, conserve benthic habitat, protect vulnerable stocks, and protect cultural resources. Many MPA’s achieve multiple objectives. Over 40 named MPA’s, many of which include several sites, encompass virtually all Federal waters off Alaska and most of the state waters where commercial fisheries occur. All of the MPA’s include measures to prohibit a particular fishery or gear type (particularly bottom trawls) on a seasonal or year-round basis, and several MPA’s prohibit virtually all commercial fishing. Although the effectiveness of MPA’s is difficult to evaluate on an individual basis, as a group they are an important component of the management program for sustainable fisheries and conserving marine biodiversity off Alaska.

Field application of anabolic steroids in carp seed production. II. Rearing of spawn to fry stage.

Two synthetic androgenic steroids, Ethylestrenol (17 β - Hydroxy - 17 α ethyl - estr - 4 - en - 3 - one) and Stanozolal (17 β - Hydroxy- 17 α - methyl - 5 a - androstano - 3, 2 - C - pyrazole) were fed via diet at 3 ppm to the spawn of Rohu and Mrigal which were reared up to fry stage over a period of 15 days in earthen carp nurseries. Both hormones enhanced growth of spawn. A maximum of 25.78% increase in length and 25.69% increase in weight as compared to the controls has been recorded. Growth rate was recorded to be 0.8 mm & 2.48 mg/day (control), and 1.13 mm & 2.67 mg/day (Stanozolol treated) in case of Mrigal spawn; and 0.91 mm & 2.39 mg/day (control), 1.12 mm & 2.90 mg/day (Ethylestrenol treated), and 1.10 mm & 2.57 mg/day (Stanozolol treated) in case of Rohu spawn. A decrease in the values of Relative Condition Factor upon hormone administration was also noticed.

Cryopreservation of sperm of common carp, Cyprinus carpio and silver barb, Barbonymus gonionotus for genetically improved seed production

Experiments were conducted to develop and standardize the protocols for cryopreservation of sperm of common carp, Cyprinus carpio and also for using the cryopreserved sperm for fertilization of eggs. Nine extender solutions as Alsever's solution, kurokura-1, kurokura-2, urea egg-yolk, egg-yolk citrate, 0.6% glucose, 0.9% NaCl, Ma and Mb, and five cryoprotectants namely ethanol, methanol, dimethylsulfoxide (DMSO), dimethylamine (DMA) and glycerol were tested. The cryoprotectants were mixed at 10% concentration of the extenders (v/v) to make the cryodiluents. Milt and cryodiluents were mixed at a ratio of 1:9 for Alsever's solution, kurokura-1, kurokura-2, 0.6% glucose and 0.9% NaCl, 1:4 for urea egg-yolk, egg-yolk citrate, Ma and Mb. Among the cryodiluents Alsever's solution mixed with either ethanol or methanol was found to be suitable and it produced more than 90% and 80% spermatozoan motility at equilibrium and post-thaw periods, respectively. Kurokura-1 and kurokura-2 when mixed with the same cryoprotectants showed good spermatozoan motility at equilibrium period (80-90%) but the motility was reduced (30-55%) at post-thaw state. Other extenders did not produce acceptable sperm-motility and in some cases the frozen milt became clotted. Different dilution ratios (1:1, 1:2, 1:4, 1:5, 1:7, 1:9, 1:12, 1:15, 1:20) were formulated for obtaining a suitable milt dilution, the dilution ratio of 1: 9 (milt : cryodiluent) demonstrated the highest post-thaw spermatozoan motility (80%) in Alserver's solution. The optimum concentration of cryoprotectants in the cryodiluents was determined, 10% concentration level was found to be effective to produce the highest number of spermatozoan motility in comparison to the other concentrations (5%, 15%, 20% 30%). Sperm preserved with the cryodiluent Alsever's solution along with either methanol or ethanol was found to be effective to fertilize eggs and produce hatchlings. The hatching rates ranged between 1.48% and 14.76%, compare to control. The fish produced through use of cryopreserved sperm and normal sperm were found to grow well and no significant (P<0.05) growth difference was observed between them. In case of silver barb, Barbonymus gonionotus, sperm tested against six extenders such as egg-yolk citrate, urea-egg-yolk, kurokura-1, kurokura-2, 0.9% NaCl and modified fish ringer (MFR) solution. Cryoprotectants used were the same as those of C. carpio. Milt was diluted with the cryodiluent at a ratio of 1:4 for egg-yolk citrate and urea-egg-yolk, 1:5 for kurokura-1 and 1:9 for 0.9% NaCl, MFR and kurokura-2. The cryoprotectant concentration was maintained at 10% of the extender (v/v) in all the cases. Among the extenders, egg-yolk citrate and urea-egg-yolk mixed with 10% DMSO, methanol and ethanol produced 50% post-thaw spermatozoan motility, whereas DMA and glycerol provided only 10% motility. Trials on milt dilution ratio and cryoprotectant concentration are being conducted. Fertilization trials are also underway.

Euglenophytes in aquaculture ponds - their ecology and role in fish production

The ecology of euglenophytes and their role in fish production were studied in 12 small earthen ponds beside the Faculty of Fisheries, BAU from July to November 2001. Four experiments each with three replications were conducted and those were as follows: pond treated with both poultry droppings and cowdung (T1); pond treated with only poultry droppings (T2), and pond treated with only poultry droppings (T3), while the control (T4) where no organic manure was applied. Fishes comprising of rohu (Labeo rohita), catla ( Catla catla), mrigal ( Cirrhinus cirrhosus), silver carp (Hypophthalmichthys molitrix) and silver barb (Barbonymus gonionotus) were stocked at the same stocking density of (10,621 fish/ha) and species ratio (1:1:1:2:2). The stocked fishes were fed with a common supplemental diet comprising of mustard oil cake and rice polish (1:1) at the rate of 4% of body weight per day. The highest cell density of euglenophytes was found in the ponds of T2, where poultry droppings were applied and was followed by T1, where both poultry droppings and cow dung were applied. Higher temperature, nitrate-nitrogen, phosphate-phosphorous and acidic pH were found to be conducive for the bloom of noxious euglenophytes. The bloom was found to use up most of the nutrients resulting in reduction in the growth of beneficial plankters and planktivorous fishes. The SGR (%/day) of catla, rohu and mrigal was lower during heavy bloom period while that of silver carp and silver barb were comparatively higher. The mortality of fishes in a pond of T2 during the bloom period was possibly due to formation of anoxic situation (dissolved oxygen level as low as 0.34 mg/1) in the early mornings through bacterial decomposition of the settled dead individuals or due to the combined effect of anoxic situation and toxic metabolite secretion by the euglenophytes.

Statistical quality control charts on attributes in fish processing technology

Apart from the use of statistical quality control chart for variables or attributes of food products in a food processing industry, the application of these charts for attributes of fishery products is explained. Statistical quality control chart for fraction defectives is explained by noting defective fish sausages per shift from a sausage industry while control chart for number of defectives is illustrated for number of defective fish cans in each hour of its production of a canning industry. C-chart is another type of control chart which is explained here for number of defects per single fish fillet sampled a1l random for every five minutes in a processing industry. These statistical quality control charts help in the more economic use of resource, time and labour than control charts for variables of products. Also control charts for attributes exhibit the quality history of finished products at different times of production thereby minimizing the risk of consumer rejection.

Management of euglenophytes in aquaculture ponds for improvement of fish production

Four experiments each with three replications were conducted in 12 experimental ponds to control the euglenophytes bloom viz. treatment 1 (T1, covering of one third of the water surface by duckweed (Lemna minor); treatment 2 (T2), application of 123.5 kg lime/ha/month; treatment 3 (T3), use of both duckweed as in T1 and lime as in T2; treatment 4 (T4) was considered as control where neither duckweed nor lime was applied. Fishes comprising of rohu (Labeo rohita), catla (Catla catla), mrigal ( Cirrhinus cirrhosus), silver carp (Hypophthalmichthys molitrix) and silver barb (Barbonymus gonionotus) were stocked at the rate of 1080 fishes/ha with the species ratio of 8:4:6:9:13, respectively. The lowest cell density of euglenophytes was found in the ponds of T3 followed by T2, and T1. In the ponds of T3, euglenophytes bloom did not occur possibly due to alkaline pH, shade and nutrient absorption by duckweed. Thin bloom was observed in the ponds of T1 where pH was neutral or slightly alkaline. The grazing on euglenophytes by the silver carp and silver barb also had some contribution in controlling the bloom. Growth of fishes was comparatively higher in the ponds of T3 and T1, which might be due to better water quality and availability of adequate food while the lower fish growth as recorded from the ponds of T4 might be due to euglenophytes bloom. Thick bloom inhibited light penetration which hampered photosynthesis and growth of other phytoplankton that are the preferred food of planktivorous fishes. Mortality of fishes in ponds having euglenophytes bloom was possibly due to formation of anoxic situation in the early morning or due to the combined effect of anoxic situation and toxic metabolites secretion by the euglenophytes.

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.

Influence of a fish bacterium Lactobacillus sp. on the production of swordtail xiphophorus helleri (Heckel 1848)

The influence of a fish gut bacterium Lactobacillus sp on the production of swordtail Xiphophorus helleri was studied for a period of one year. The Lactobacillus sp P21 produced bacteriocin-like inhibitory substance and exhibited wide spectrum of action against Aeromonas hydrophila, Bacillus spp, Pseudomonas spp and Citrobacter freundi in vitro. The growth performance of X. helleri reared in the presence of Lactobacillus P21 at 106/ml rearing water was better than the control. The total plate counts, total MRS agar counts and the counts of motile aeromonads, presumptive pseudomonads, lactose fermenters and lactose non-fermenters in the gut of probiotic group were comparatively low than the control. On day 60 the count of Lactobacillus sp P21 was observed to be log 5.28/g in the gut of X. helleri indicating colonization of this bacterium in the gastrointestinal tract. The fecundity of X. helleri was in the range of 9-134. On average, it produced from 39.42±18.72 fry/female in control group to 53.00±23.57 fry/female in probiotic group. The increase in average fecundity in probiotic group over the control group was about 25%. There existed significant difference between probiotic group and control in respect of average fecundity/female (p<0.02), average number of fry survived /female (p<0.006) and average number of fry dead/female (p<0.029). The results of the present study demonstrated that the rearing of X. helleri in probiotic-enriched water have growth inducing ability and favourably influenced the reproductive performance in terms of high fecundity, high fry survival, reduced fry mortality and reduced fry deformity.

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.

Enhancement of fish production in a reservoir after partitioning by dikes through community participation

A reservoir of 70 acres was portioned by dikes into four manageable big ponds to get more production of fishes at Basurhat, Noakhali, Bangladesh under the supervision of local community through a society of 40 people ownership. Pangus (Pangasius hypophthalmus) @ 20,000/acre, and then fry and fingerlings of different types of fishes such as catla (Catla catla), rohu (Labeo rohita), mrigal (Cirrhina mrigala), grass carp (Ctenophmyngodon idella), bighead (Aristichthys nobili), silver carp (Hypophthalmichthys molitrix), common carp (Cyprinus cmpio) and rajpunti (Puntius gonionatus) @ 500/acre were stocked. Feed containing 25% protein was used two times daily and feed was adjusted fortnightly. After 8 months, all the fishes were weighed 0.80-2.10 kg except rajpunti (150-200 g) and tilapia (150-220 g), and a total of 25 ton of fish was harvested which was five times higher than the previous production under signal ownership. The production of fishes were increased after partitioning the lake with dikes due to proper management and control.

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.

A study of the constraints affecting ornamental fish production in Sri Lanka

Although Sri Lanka is endowed with favourable climatic conditions and resources for breeding and rearing ornamental fish for export, a considerable number of ornamental fish producers as well as exporters have given up the industry within a relatively short period of time. This study was conducted to understand the present status of the industry and to identify the problems that have caused these failures. The study was conducted from March to December in the year 2007 and covered Colombo, Kaluthara, Polonnaruwa, Negombo, Wattala, Rathnapura, Avissawella, Kandy, Kegalle, Padukka, and Gampaha areas, where ornamental fish culture is known to be popular. The survey was carried out by interviewing ornamental fish farmers using a structured questionnaire survey that was designed to elicit the required information. Most (75%) of those surveyed were identified as small scale farmers. A majority (56%) of them used only cement tanks for their culture activities. Only 47% of farmers had proper technical knowledge or training on fish culture while 42% directly supplied their fish products to the expo1iers. The most important constraints identified by the study were as follows: (1) the sale price offish not changing in keeping with the increase in the material costs of production - Feed, cement, sand, transport and labour - in recent years. (2) Difficulty to find export markets for newcomers to enter the export market. (3) Lack of quality brooders and information on the most suitable fish varieties for the different climatic and water conditions in different areas in the country (3) Feed availability and cost. (4) Lack of adequate knowledge and technical support with regard to disease control and water quality management. (5) Difficulty to survive in the off season. (6) Difficulty in obtaining credit for expansion and the lack of sufficient involvement of responsible authorities in overcoming all these identified constraints.

The water hyacinth problem and the biological control option in the highland lake region of the upper Nile basin: Uganda's experience

The rapid proliferation and extensive spread of water hyacinth Eichhornia crassipes (Mart) Solms in the highland lakes of the Nile Basin within less than 15 years of introduction into the basin in the 1980s pauses potential environmental and social economic menace if the noxious weed is not controlled soon. The water weed has spread all round Lake Victoria and, in Uganda where infes tation is mos t severe, water hyacinth estimated at 1,330,000 ton smothers over 2,000 ha of the lakeshore (August,1994). Lake Kyoga which already constantly supplies River Nile with the weed is infested with over 570 ha, while over 80% of the river course in Uganda is fringed on either side with an average width of about 5m of water hyacinth. As the impact of infestation with water hyacinth on water quality and availability, transportation by water, fishing activities, fisheries ecology, hydro-power generation etc becomes clear in Uganda, serious discussion is under way on how to control and manage the noxious weed. This paper pauses some of the questions being asked regarding the possible application of mechanical and chemical means to control the water weed.Uganda has already initiated the use of biological control of water hyacinth on Lake Kyoga with a strategy to use two weevils namely Neochetinabruchi and Neochetina eichhorniae. The strategy to build capacity and infrastructure for mass multiplication and deployment of biological control of the weevils in the field developed in Uganda by the Fisheries Research Insti tu te (FIRI) and the Namulonge Agricultural and Animal production Research Insti tute (NAARI) is proposed in outline for evaluation. Plans to deploy this strategy on lake Kyoga are under way