Research Symposium-2010

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Browsing Research Symposium-2010 by Subject "Aquaculture and Fisheries"

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    Development of a Low Cost Fish Feed for Rearing Ornamental fish Guppy(Poecilia reticulate)
    (Uva Wellassa University of Sri Lanka, 2010) Wanigasekera, W.M.K.G.S.B.; Ariyaratne, M.H.S.; Kithsiri, H.M.P.; Jayamanne, S.C.
    Cost of feed is the main bottleneck for the development of ornamental fish industry in Sri Lanka. The present study concentrated on developing a low cost aqua feed for guppy (Poecilia reticulate) to reduce the burden of feed cost. Two aqua feed types (Aqua feed I, Aqua feed II) were prepared by using locally available feed ingredients and tested against a commercial feed (control). A total of 1350 P. reticulate fry of average length 2.76 ± 0.025 cm and average weight of 0.28 g ± 0.03 g were used to determine the performance of the two feed types. Complete randomized block design was used to analyze the data of the eight weeks feeding trial with three treatments which contained three replicates. Weights and lengths were measured biweekly. Growth performance and total cost of feed production parameters were assessed using the Feed Conversion Ratio (FOR), Specific Growth Rate (SGR) Survival rate, Weight gain, Condition Factor and Average daily growth (ADG). The trial groups reached a mean live length of 3.50 ± 0.0764 cm, 3.80 ± 0.0361 cm , 3.70 ± 0.0351 cm and mean live weight of 0.41 ± 0.06526 g, 0.62 ± 0.00541 g, 0.51 ± 0.07974 g at the end of the trial when fed with aqua feed I, aqua feed II and commercial feed respectively. Growth data indicates that the final length, weight, ADG, SGR and weight gain values of all three feeds were not significantly different( P<0.05) but the best (lowest) mean FOR and condition factor was obtained from Aqua feed II (P<0.1). Therefore, it can be concluded that aqua feed II is the best among three feeds. Key words: Guppy, Poecilia reticulate, feed, growth, Aqua feed, Commercial feed
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    Investigation of Occurrences of Mercury Level in Tuna Fesh (Thunnus albacares) in Relation to it Habitat and Size Variation
    (Uva Wellassa University of Sri Lanka, 2010) Weththasinghe, M.P.; Abeyrathne, E.D.N.S.; Jayamanne, S.C.; Karunarathne, B.
    Mercury is poisonous to human being and the level of mercury in fish is regarded as high when it exceeds 0.3 ppm. Mercury level is a hazard point in fish processing and finding ways in reducing the hazards of mercury is important for export market. In this study, distribution of mercury in yellowfin tuna in relation to its habitat and size was investigated. Three hundred and sixty samples of fish were collected from 120 individuals from four fish landing sites; Galle, Trincomalee, Dondra, and Negombo. From each fish three samples were collected from head, underneath the pectoral fin and tail end respectively. Mercury content in each part was analysed using Atomic Absorption Spectroscopic method. Total mercury levels in four landing sites; Galle, Trincomalee, Dondra, and Negombo ranged from 0.0733 ppm to 0.2225 ppm with reference to yellowfin tuna. Highest mean mercury level (0.1668 ppm) and highest variation of mercury (±0.0327) was recorded at L.ondra. The lowest mean mercury level (0.1048 ppm) was recorded at Galle. Mercury level in tuna harvested from eastern coast of Sri Lanka was significantly higher than the mercury level in tuna harvested from western coast. This suggests that mercury gets distributed through oceanic currents. Weight and mercury level of tuna showed a positive correlation (R2 = 0.123) while fork length of fish and mercury level of fish has shown a negative correlation (R2 = 0.123). Body location of the fish has no significant effect on the deposition of mercury in tuna. Keyword: Mercury level, Yellowfin tuna, Landing site, Body location, Weight
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    Investigation of Regions Free of White Spot Syndroms Virus Contamination in Wild P. monodon Brooders to be Used as Broodstock Resoure for Shrimp Hatcheries
    (Uva Wellassa University of Sri Lanka, 2010) Nathiya, M.Y.F.; Wijegoonawardane, P.K.M.; Bulumila, P.B.A.I.K.; Jayamanne, S.C.
    At present White Spot Disease (WSD) is one of the most serious viral diseases affecting farmed shrimp species globally. The causative agent, White Spot Syndrome Virus (WSSV), is extremely virulent, and has a wide host range and can also be inherited. The present study reports the prevalence of WSSV, in the wild P. monodon brooders collected from different geographical locations around Sri Lanka and analyzed using Polymerase Chain Reaction (PCR). Out of 156 selected brooders, a total of 60 individuals were positive for WSSV either by 1-step or 2-step nested PCR (nPCR). Out of 60 positive samples, the infection intensity was mild in 42 brooders while the other 16 showed higher infection intensity. The overall percentage positivity was 38.46% (60 of 156; 95% Confidence Interval of 30.19% to 45.93 %) and revealed that the brooders along the coast of Sri Lanka were infected by WSSV and they can act as carriers. Among the different geographical locations Negombo displayed the lowest WSSV prev.alence significantly (P<0.05). WSSV prevalence in North Western, Eastern and Western province was found to be 61.54%, 57.69% and 28.44% respectively. The WSSV isolates present in brooders were subjected to 2-step WSSV genotype nPCR, the brooders contained 5 different TRS (Tandem Repeat Sequence) genotypes (4, 6, 9, 14 and 15-TRS) and the 6¬TRS was the most predominant. As earlier studies have shown that 6-TRS type was commonly associated with disease outbreaks, it could be speculated that major route of WSSV transmission in Sri Lanka could be vertical. More information from expanded geographical locations around Sri Lanka would allow zoning of WSSV free zones and to formulate better P. monodon broodstock management strategy to sustain the shrimp industry in Sri Lanka. As a precautionary measure and to control further contaminations of the wild, strict bio-security measures should be adhered during WSSV outbreaks. Key words: White spot syndrome virus (WSSV), Nested PCR (nPCR), Polymerase Chain Reaction (PCR)