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Theses

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2010 - 20124
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Subject: Aquaculture × End date: 2012 × Start date: 2010 ×
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    ThesisItemOpen Access
    Integrated culture of fish with micropropagated plants in a recirculatory system
    (Department of Aquaculture, College of Fisheries,Panangad, 2012) Navya, R; KAU; Devika Pillai
    An experiment was designed to study an integrated recirculatory sytem with micropropagated aquarium plants, fish and indigenous filter materials like coir, vetiver and bamboo as the filter media. The plants selected for the study were Bacopa caroliniana, Anubias minima, Aponogeton ulvaceus, Rotala rotundifolia and Nymphoides cristata. The first part of the work was to standardise the micropropagation techniques for the above said plants. Murashige and Skoog medium (half and full strength) was used as the basal medium for the establishment of cultures. The explants varied from nodal segments, rhizome buds, leaf petioles and lateral buds. Surface sterilization was carried out with a range of sterilants like mercuric chloride solution, ethyl alcohol, sodium hypochlorite solution etc. for varying durations and concentrations depending on the type of explant. Effect of growth regulators on explants were studied using auxin IAA and cytokinins, BA and Kn. A liquid culture media with 1.5mg l-1 BA and 0.1mg l-1 Kn concentrations was the best medium for Bacopa caroliniana. A combination of auxin cytokinin like 1.5 mg l-1 BA and 1.0 mg l-1 IAA in liquid culture was the best medium for Rotala rotundifolia. In Nymphoides cristata, hormone concentration of 1.0 mg l-1 each of BA and IAA in liquid culture gave the best results. In Anubias minima, a full MS solid medium with 6.0 mg l-1 of BA gave better results compared to lower levels of BA. In vitro trials for Aponogeton ulvaceus was not successful due to the exudation of phenolic extracts in all the treatments which eventually lead to the death of the tissues. Hardening success was 90 percent, 100 percent, 70 percent, 100 percent in the case of Anubias minima, Nymphoides cristata, Rotala rotundifolia and Bacopa caroliniana respectively. The micropropagated plants were incorporated in the recirculatory system along with fish and three different biofilter materials like coir, vetiver and bamboo splits. The study focused mainly on the filtering efficiency of the three filters based on the nitrification curves. The plants were included in the system to be a part of biofilter and their exclusive role in nitrification was not studied since this is a preliminary work. A nitification graph was plotted with the observed values of ammonia, nitrite and nitrate in the three different biofilter systems and compared with a control. It was inferred that coir fibres were the best of filter materials tried in nitrification followed by bamboo and vetiver. The control system took more time (45 days) in stabilizing ammonia levels due to lack of a substratum for growing nitrifying bacteria.
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    ThesisItemOpen Access
    Characterization of different stocks of Macrobrachium rosenbergii and development of genetically improved strain through selective breeding
    (Department of Aquaculture, College of Fisheries, Panangad, 2010) Shyla, G; KAU; Mohanakumaran Nair
    Giant freshwater prawn Macrobrachium rosenbergii (de Man, 1879) is an important species suitable for culture in inland and low saline coastal water bodies. Information on the genetic structure and variation among cultured species are essential for genetic approaches to optimize conservation strategies and breeding programmes for improving stocks. DNA based markers can be used to assess more precisely the genetic variations in the entire genome. Natural populations of M. rosenbergii inhabiting the rivers in different geographical areas of India show wide variation in morphological traits and economic characters. The present work envisages studying the genetic diversity of wild populations of M. rosenbergii collected from different parts of India through phenotypic characters and molecular marker studies. It also aims to develop a superior strain by combining the desirable characters through selective breeding. In this study genetic characterization of Andhra Pradesh (AP), Orissa (OR) and Kerala (KR) stocks of Macrobrachium rosenbergii were done with RAPD and Microstellite markers. Marker analysis showed variation between stocks and AP showed more genetic distance from OR and KR populations.Moreover KR stock from Achankoil River showed slight similarity with AP. Phenotypic trait analysis was done with three stocks. Egg diameter, larval hatch fecundity, larval rearing period, survival rate and larval length were estimated. Highest egg diameter and hatch fecundity were shown by OR and KR populations. AP showed minimum larval rearing period and maximum survival rate. Maximum larval length was for KR. Stress tolerance studies were conducted in V and X stage of M.rosenbergii larvae with temperature, salinity, formaldehyde and ammonia to estimate the relative differences in the ability of different populations to withstand stressed conditions. Among base population KR population showed highest tolerance towards temperature, salinity, formaldehyde and ammonia.Stage wise tolerance variations also found in all populations. X stage showed more tolerance to all stressors except ammonia. Comparison of other economically important parameters such as disease resistance, quality of flesh, percentage survival, growth rate, percentage morphotypes and head tail ratio were also done. Disease resistance was tested with white tail virus and bacteria (Enterococcus aerogenes) by challenge study. In both studies KR population exhibited better tolerance than other populations. Prophenoloxidase activity and total haemocyte count was also estimated in infected prawns to check the immune response. Here again KR showed higher activity and count. Flesh quality of three populations was estimated by carcass proximate analysis. In this study, no variation in body composition was shown by three stocks. Percentage survival rate and weight gain of three populations in cage were estimated. Maximum survival rate was found in AP and highest growth was found in KR stock. Analysis of percentage morphotypes of various populations showed the maximum OC for AP and SM for OR stock, with no significant variations in percentage BC and female prawns, head tail ratio, which was calculated to find out the yield of meat revealed the least ratio for KR. Large healthy prawns of the three stocks were selected from families showing better performance. Breeding experiment was conducted to produce six crosses viz. Andhra Pradesh (male)×Orissa (female) APOR, Orissa (male) × Andhra Pradesh (female) ORAP, Andhra Pradesh (male) × Kerala (female) APKR, Kerala (male) × Andhra Pradesh (female) KRAP, Orissa (male) × Kerala (female) ORKR, Kerala (male) × Orissa (female) KROR. Different phenotypic characters and economically important traits of F1 generations of hybrids were also studied. KROR showed better egg diameter, hatch fecundity, larval survival rate and larval length. But larval rearing period was minimum for APKR. KROR showed resistance to viral and bacterial diseases, which was similar to that of KR and better than other hybrids. In cage culture APOR showed better survival rate, while growth rate was significantly higher for KROR, which was more than that of base populations. Analysis of percentage morphotypes showed a similar pattern as that of base populations. Lower head -tail weight ratio was shown by KROR, which was lower than that of KR. Estimation and comparison of heritability of weight of three better performing hybrids were done. From the data it was found that maximum heritability of weight was for KROR (.75) followed by APKR (.161) and APKR exhibited no heritability.
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    ThesisItemOpen Access
    Survey and disease surveillance of newly introduced L. Vannamei (Boone, 1931) in India
    (College of Fisheries, Panangad, 2011) Roshan Maria, Peter; KAU; Devika, Pillai
    P. monodon (tiger shrimp) was the most preferred cultured species in India, but repeated occurrence of diseases especially white spot disease (WSD) caused by white spot syndrome virus (WSSV) had a severe setback to the shrimp culture industry. This prompted the industry to actively promote the introduction of a non-native species, the Pacific white shrimp, Litopenaeus vannamei, as an alternative to P. monodon for commercial aquaculture operations in the country. The authority to issue licenses to take up L.vannamei culture was vested with the Coastal Aquaculture Authority (CAA), who issued licenses for 1,208 aqua farmers in 2009. Availability of SPF stock, ability to grow well even at high stocking densities, reduced days of culture (DOC), lesser protein requirement (28-35%) and demand in the international market attracted aquafarmers to switch to culture of L.vannamei. A survey carried out in the Nellore district of Andhra Pradesh to understand the level of acceptance and the nature of culture practice among the farms culturing L.vannamei revealed that only 33% of the farms surveyed had obtained permission from the CAA, 41% followed biosecurity measures and merely 10% had the facility for Effluent Treatment System. 53% practised chlorination and de-chlorination of water during water exchange and only 38% farms maintained trained personnel. It was observed during the survey that only 84% procured tested SPF seed from certified hatcheries. While 90-92% of yhe farms depended on pelleted feed, only 80-85% of the farms surveyed carried out regular monitoring every 1-2 weeks. Disease surveillance in the farms surveyed did not detect the presence of any of the major shrimp viruses (WSSV, IHHNV, MBV, HPV and TSV) in the 60 samples screened using molecular methods. However, Vibrio sp. was detected in samples exhibiting obvious signs of bacterial disease. High stocking densities without adequate number of aerators can be stressful to the shrimps and might be the reason for bacterial infection. Economic analysis indicates that L.vannamei culture is more profitable than P.monodon culture.
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    ThesisItemOpen Access
    Comparative evaluation of different feed ingradients for stinging catfish heteropneustes fossilis(Bloch)
    (College of Fisheries, Panangad, 2010) Kumar, Katya; KAU; Mohanakumaran, Nair
    Stinging catfish Heteropneustes fossilis (Bloch) is commercially and nutritionally important in India, fetching high price locally and enjoying good potential for aquaculture. One of the major limiting factors restricting the expansion of H. fossilis culture is the high cost of trash fish used as feed for its grow out. Trash fish supply is irregular and unreliable and not always recommended in fish culture. In the present study an attempt was made to evaluate different feed combination as replacement diet for trash fish in the growout of H. fossilis using three sources of protein. Three isonitrogenous diets containing 40% of protein viz. fish meal (FM), clam meat (CM) and soymeal (SM) as protein sources were tested, with five replications for each treatment, and fed to the fingerlings of H. fossilis of initial size.(11.22 ± 1.27g and 12.24 ± 0.40 cm), collected from the wild and acclimated for two weeks in freshwater and stocked in 380L capacity cement cisterns at a density of 10 numbers per tank, provided with soil substratum. Tapioca flour and vitamin mixture were added at the rate of 10% and 1% respectively in all the feeds, while rice bran constituted 36%, 18.6% and 23.3% in FM, CM and SM feeds respectively. The test feeds were fed to the fingerlings at the rate of 5% of body weight, twice daily for duration of 42 days. At the end of the trial, final length and weight measurement of each juvenile in treatments were made, and the data statistically analyzed, using One-Way ANOVA. Multiple comparisons of mean values were carried out using Tukey’s HSD test, and the means were compared using two sample Student’s t-test. Water quality parameters in the experimental tanks were monitored weekly. All the treatments recorded cent percent survival, and there was no significant difference in length gain among the three feeds. Although the highest weight gain was obtained from the FM (8.56 ± 2.40g), followed by SM (6.09 ±1.40g) and CM (5.68 ± 0.72g) respectively, statistical analysis revealed that there was no significant difference between FM and SM treatments, indicating that soymeal is equally good as fish meal. However the lowest food conversion ratio (FCR) of (2.74) for FM, followed by CM (4.07), and SM (4.53), which suggest that fish meal is the best source of protein in the feed for the culture of H. fossilis, but soymeal could also be used to replace fish meal, upon further refinement of growth trials. Highest ammonia was recorded in FM tanks, followed by CM and SM, which indicate that water quality needs to be closely maintained, when sources of animal protein are used in the feed of H. fossilis. Additional research is recommended, supplementing the deficient amino acid lysine in soymeal, which might perhaps improve the weight gain and FCR of H. fossilis fingerlings.