Seed production and culture techniques of Genetically Improved Farmed Tilapia (GIFT) in brackishwater environment

Effects of different levels of salinity on survival, growth and gonadal development of Genetically Improved Farmed Tilapia (GIFT) were studied under laboratory conditions in glass aquarium, for a period of ten weeks. The initial individual size of the GIFT was 20.23±4.45 and the salinity levels tested were 0, 5, 10, 15 and 20 ppt. The highest survival of 87.5% was found in 0 ppt and the lowest 60.5% in 20 ppt. Though the survival decreased progressively with increased salinity, there were no significant differences (P>0.05) among 0, 5, and 10 ppt. Similar to what has been observed in survival, the specific growth rate (SGR %/day) also decreased as of 1.30, 1.24, 1.08, 0.90 and 0.71, respectively, with the increased salinity of 0, 5, 10, 15 and 20 ppt. The gonadal development was highest in 0 ppt with a GSI value of 3.75 and lowest of 2.01 in 20 ppt. In the second experiment, gonadal development and seed production performance of GIFT in brackishwater condition were investigated for a period of three months. Each of the three fine meshed hapas of 20 square meters made from nylon net was placed in a freshwater (0 ppt) and in a brackish water (10-15 ppt) pond of the Brackishwater Station (BS). GIFT of 65 g average weight from a single cohort were stocked into three hapas at a rate of 2 per m. The male vs female ratio was 1:3. The development of gonad was faster with the higher gonadosomatic index (GSI %) of 3.85 % in freshwater condition than that of 2.73 % in brackish water. Within three months of the study period, a total of 70,510 and 44,250 GIFT fry were produced respectively, in freshwater and brackishwater conditions. Finally under third experiment, a participatory on-farm trial was carried out to evaluate the production performance of GIFT in monoculture and in polyculture with silver barb in coastal freshwater pond conditions. Nine ponds were selected for three treatment combinations of GIFT monoculture (T1), GIFT and silver barb polyculture (T2), and silver barb monoculture (T3). The ponds have been stocked in April, 05 at a density of 25,000 fry per ha. Fishes were fed with rice bran at the rate of 6% bw per day. In one month culture period, GIFT attained an average weight of 16.27 g in monoculture and 17.23 g in polyculture, against an average stocking weight of 0.37 g. Silver barb reached an average weight of 16.62 g in polyculture with GIFT and 10.01 g in monoculture, against an average stocking weight of 3.79 g

Impact of stocking density on growth and survival rate of mud crab (Scylla serrata Froskal)

A 10-weeks culture trial of mud crab, Scylla serrata in brackish water earthen pond was conducted in different stocking densities. The aim of the experiment was to identify a suitable stocking density for optimum production. There were three treatment as 5000 crab lings/ha, 10000 crab lings/ha and 15000 crab lings/ha of each with three replications. The initial mean weight of crab lings were same (5.5 ± 0.13 g). The experimental month was June '95 to August '95. The size of each pond was 500 m². To maintain good water quality water was exchanged in every spring tide. The salinity during the experiment were 2-18ppt. Prepared feed of about 32% protein consisting fish meal, MOC rice bran and wheat flour was used at 5% of their body weight. In terms of production, survival rate, growth and carapace width, the stocking density having 10000/ha showed the best (P<O.O5) performance followed by 5000/ha and 15000/ha

The aquaculture of Scylla species in India

Among Portunid crabs, Scylla species are commercially important in aquaculture, capture fisheries and trade, and have created wide interest and high preference in India. Part of the 70,000 ha of brackishwater ponds developed for aquaculture in the southern states of Peninsular India is suitable for conversion to crab farming. Crab culture technology developed in the Central Marine Fisheries Research Institute has recently led to increasing interest in crab farming. Surveys have been conducted to identify resource grounds and seasons for collection of wild seeds. However the inadequate supply of seedstock is a limiting factor in promoting the expansion of the industry. Environmental manipulation strategies have been developed to maintain broodstock and produce gravid females. Further refinements of hatchery technology could meet the demands for seed supply and promote culture activities. Crab production ranged from 1,500 to 2,500 kg•ha-1•crop-1 using different culture methods. Based on the economics of different culture methods, fattening is more remunerative than monoculture and polyculture. Post-harvesting techniques and marketing aspects are discussed. Management measures are highlighted to promote conservation of stock for sustainable yield

Scope for Mussel Farming in Brackish Waters

The present study was carried out by the Central Marine Fisheries Research Institute in two coastal districts of Maharashtra with the main objectives ' i) to estimate the returns to capital and labour and ii) to compare employment pattern on mechanised boats and country crafts fitted with OBE. The present report mainly deals with the first objective of the stud

Species diversification in coastal aquaculture: production potentials of shrimp (Penaeus monodon) with mono and mixed sex tilapia

An experiment of 120 days of culture was conducted in brackishwater earthen ponds having an area of 0.2ha each. The hatchery produced shrimp (Penaeus monodon) post larvae were stocked in the 40m² fine meshed nylon net nursery enclosures were fed with commercial pellet feed. After two weeks of nursing, juveniles were allowed to spread in cultural pond by opening the fence. Fingerlings of three different strain of tilapia were stocked as shrimp and Strain-1 all male (monosex) (T1), shrimp and Strain-2 all male (T2), shrimp and Strain-3 mixed sex population (T3) @ 20.000/ha and 10.000/ha, respectively and shrimp only (monoculture) (T4) @ 20.000/ha. The shrimp and fish were fed with farm made feed consisting of a mixture of fishmeal 29%, MOC 15%, rice bran 30%, soybean meal 16%, wheat flour 9% and vitamin premix 0.1%. The average final weight of shrimp was 24.9±1.13g, 23.41±3.26g and 26.67±1.89g that stocked with tilapia in treatments T1, T2, and T3 respectively. The final average weight of shrimp in monoculture (T4) was 27.41±0.76g, apparently higher but insignificant in treatments. The survival of shrimp was 42.17%, 32.38%, 39.45% and 61.98% in treatments T1 T2, T3 and T4 respectively. The production of shrimp in concurrent culture was 193.67, 154.26 and 210.41kg/ha in T1, T2 and T3, respectively, while in monoculture (T4) was 339.77 kg/ha. The growth and survival of tilapia among the treatments was insignificant. The growth of monosex tilapia ranged 225.29 and 291.31g and survival 62.77 and 72.20% in T1 and T2, respectively, in mixed sex was 193.0g and 83.20% (T3). The production of tilapia monosex strains was 1676.69kg/ha (Strain-2 all male) and 1668.98 kg/ha (Strain-1 all male) while that of Strain-3 mixed sex population was 1622.92 kg/ha

Effects of cowdung application on the production of mud crab (Scylla serrata Forskal) in brackishwater pond

A culture experiment of mud crab for 84 days was conducted in earthen pond at Brackishwater Station, Bangladesh Fisheries Research Institute, Paikgacha, Khulna. The aim of the experiment was to study the effects of cowdung application on crab production and water quality. There were three treatments as without cowdung (T1), 500 kg cowdung/ha/fortnight (T2) and 750 kg cowdung/ha/fortnight (T3) with three replicates for each. The result was evaluated on the basis of growth, production, survival rate etc. The experimental months were mid-April '96 to mid-July '96. To maintain a good water quality, water was exchanged in every spring tide. The range of salinity during the experiment was 8-19 ppt. Trash fish and fresh shrimp head were used as feed on raw basis in every alternate week at a rate of 8% body weight of crab at the same time rice bran and wheat flour were used at a rate of 2% body weight as a source of carbohydrate. The production of T1, T2 and T3, were 720.35 kg, 862.16 kg and 669.19 kg/ha respectively. Though the effects of cowdung on production of crab is insignificant but in terms of production, survival rate and growth, the study suggest that the application of cowdung in addition to feed can be recommended for mud crab culture at a rate of 500 kg/ha/fortnight

Genetic characterization of ayu Plecoglossus aliivelis aliivelis occurred in Nakaumi Lagoon

Ayu Plecoglossus altivelis altivelis is a common fish that is composed by two major forms, amphidrDmOuS and landlocked forms, based on itsannual1ife history. Althoughrecent decline in the reserves of amphidromous stocks in rivers has prompted frequent transplantations from landlocked stocks, a low survival rate of larvae of the landlocked fbm occllrS during periods of high water temperature in seawater. In brackish water environment, however, non-native landlocked form may survive and show sympatric distribution with mother populations. This study was conducted to verifythe genetic status of ayll 0cclmed in Nakaumi Lagoon, which is the second largest brackish lake in Japan. Nucleotide sequence polymoIPhism of the first 300 bp of themitochondrial DNA control region Was analyzed for 30 individuals including each 15 Specimens collected from 2 locales ofNakaumi Lagoon in May 2009, along with each 15 reference specimens oftheamphidromous and landlocked stocks. Comparatively high1evels of nucleotide substitution were observedwith 35 polymoIPhic sites from Nakatlm population and 40 sites from the amphidromous stock, as contrasted with24 sites from the landlocked stock. Based on nucleotide sequences at 5 hypervariable sites, 2 haplotypes occured in only the amphidromousstock were obtained at a high frequency in Nakaumi Population These results suggest that the amphidromous form forms the majority of Nakaum population.Article信州大学山地水環境教育研究センター研究報告 6: 125-132(2010)departmental bulletin pape

Observations on the ingression and distribution of larval prawns in the Nethravati-Gurupur estuary, Mangalore

The spatial and temporal distributions of larval prawns of penaeids and non-penaeids in the estuarine waters of Mangalore were studied. Larvae appear to be passively brought in by the incoming flood tides to the estuary, enjoy a wider distribution throughout the estuarine complex with abundance towards the mouth. The distribution of larval prawns was more in Nethravati than in the Gurupur stretch. The influence of temperature, hydrogen-ion-concentration, salinity and dissolved oxygen on the distribution of larvae in the estuaries is discussed. Inference on spawning seasons of commercially important prawns in the neighbouring waters has been arrived at based on their larval abundance

Effect of stocking density on survival and growth of mud crablings, Scylla sp. in laboratory conditions

Mud crablings, Scylla sp. were reared, for a period of six weeks in fiberglass aquarium under laboratory conditions, to determine the effect of four different stocking densities of 1, 2, 3 and 4 crabling/l of water on their survival and growth. Salinity of water was maintained at 25 ppt throughout the rearing period. Stocking rates of 1, 2, and 3 crabling/l resulted in a similar (p>0.05) survival rates of 75, 74, and 83.5%, respectively, that of 4 crabling/l resulted in significantly lower (p<0.05) survival rate of 56%. No significant difference was observed among different stocking densities in average growth of carapace length (CL), carapace width (CW) and body weight (BW)

Biochemical composition of the ovary and partial characterisation of yolk protein vitellin in Metapenaeus monoceros (Fabricius, 1798)

Yolk protein vitellin in ‘speckled shrimp’ Metapenaeus monoceros was partially characterised employing polyacrylamide gel electrophoresis (PAGE). There was an increase in the level of expression of vitellin in the ovary, with the advancement of maturation. The vitellin fraction was not expressed in immature and spent ovaries. Molecular weight of vitellin was 326 kDa. Confirmation of the vitellin band by selective staining showed that the yolk protein was a lipoglyco- carotenoprotein possessing a calcium moiety. A protein fraction with molecular weight 270 kDa, which was a lipoprotein, was expressed in ovaries of all maturity stages as well as in testis. The major biochemical constituents of mature yolk of M. monoceros on dry weight basis were protein (59.36±1.18%), lipid (31.23±2.98%) and carbohydrates (2.97±0.81%). Carotenoids accounted for 0.70±0.81% wet weight of yolk