Browsing by Author "Thushari, G.G.N"

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    Comparative Analysis on Morphological Variation of Three Populations of Saccostrea cucullata (Rock Oysters) and Crassostrea madrasensis (Indian Backwater Oyster) (Bivalve: Mollusca) in Selected Coastal Regions of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2019-02) Peiris, M.S.D; Prasadika, H.K.A.E; Thushari, G.G.N; Pitawala, J.C
    Crassostrea madrasensis (Indian backwater oyster) and Saccostrea cucullata (Rock oyster) are abundant shellfish varieties with higher culture potential along coastline of Sri Lanka. Limited research studies are available on population clustering and distribution patterns of Oysters in Sri Lankan coast. This study was focused to analyze intra-specific morphological variation among 03 populations of C. madrasensis and S. cucullata in Sri Lanka. C. madrasensis samples were collected from Panadura, Trincomalee and Kalpitiya coasts, while S. cucullata samples were collected from Dickwella, Jaffna and Mt’Lavinia during August-December 2018. Ten morphometric parameters were measured using 190 samples and standardized morphometric measurements were subjected to Discriminant Function Analysis (DFA). Two discriminant functions were derived by predicted two models for populations of S. cucullata (Function 1: Wilks’ƛ=0.005/Function 2: Wilks’ƛ=0.81, P<0.05) and C. madrasensis (Function 1: Wilks’ƛ=0.35/Function 2: Wilks’ƛ=0.82, P<0.05). Derived first Discriminant functions were identified as strongest factors by highly accounting for models of S. cucullata and C. madrasensis with of 99.9% and 85.8% of total variances respectively (Eigen values: 164.55 and 1.34). The ratio between Adductor Muscle Scar Height of Right Valve/Adductor Muscle Scar Area {AMSH(R)/Area} was selected as the highly contributing parameter on strongest function in extracted models of S. cucullata (0.68) and C. madrasensis (0.52). The group plots derived for S. cucullata indicated overlapping between two populations in Colombo and Jaffna, while population of Dickwella illustrates a clear separation from other two groups with intra-specific variation. Group plots of C. madrasensis records overlapping of populations with morphological similarity and three groups consider as one population. This study provides basic information on population structure of S. cucullata and C. madrasensis in Sri Lanka. Population genetic studies are recommended to confirm the findings of this study.
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    Evaluation of Sensory Qualities of Catla Fish (Catla Catla) in Three Selected Reservoirs of Badulla District, Uva Province, Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2019-02) Leshika, D.L.; Ediriweera, T.K.; Abeygunawardana, A.P; Siriwardana, E.M.C.; Thushari, G.G.N; Liyanage, N.P.P.; Jayamanne, S.C.
    Catla (Catla catla) is one of the common exotic Indian carp species in inland fishery sector of Uva province in Sri Lanka. There is a high potential to develop Catla fish production and introduce value added products from the excess fish harvest. Environmental factors can significantly affect the physico-chemical and organoleptic quality of fish meat. Current study was focused on investigating Organoleptic properties of Catla fish flesh from 03 reservoirs selected (Ulhitiya, Rathkinda, Sorabora reservoir) with higher fish production in Badulla district. The fish samples with weight of 6.0 -12.5 kg and length of 65cm-95 cm were collected from the landing sites of three selected reservoirs. Prepared fish fillets were subjected to steam cooking for 10 minutes without adding spices at temperature of 1000C. The sensory evaluation was conducted using 05point hedonic scale to assess the sensory characters; color, texture, aroma, mouth feel, taste, overall acceptance of the steamed fish fillets by 30 untrained panelists. Sensory scores were statistically assessed through Friedman non parametric test. As results revealed, all the sensory parameters of flesh samples are significantly different according to the type of reservoir (p<0.05). Highest estimated median for all the organoleptic parameters (color/texture/aroma/mouth feel/taste=4, overall acceptance=5)were recorded for Catla flesh samples of Ulhitiya reservoir showing that, Catla fish from Ulhitiya reservoir has highest consumer preference. Sensory qualities of fish flesh depend on different kind of factors such as characteristics of living environment, fertility of water, availability of food and climatic condition. In conclusion, consumer acceptability also depends on organoleptic properties of fish samples. Detailed study on biochemical and physical quality changes of Catla fish samples in different reservoirs is recommended improve knowledge on fish quality.
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    Preliminary Investigation on Current Status of Freshwater Fishery Sector and Sensory Qualities of Selected Food Fish in Three Selected Reservoirs of Badulla District in Uva Province of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2019-02) Weerasignghe, K.B.S; Athawuda, A.M.G.A.D; Gamage, S.; Abeygunawardana, A.P; Thushari, G.G.N; Liyanage, N.P.P.; Jayamanne, S.C.
    Sri Lanka is rich with large number of reservoirs which are highly useful for irrigational activities and inland fisheries. In Uva province, there is a high potential in expansion of freshwater fish production in reservoirs. Current status of inland fishery sector needs to be evaluated, prior to implement appropriate fishery management measures Also, assessment of organoleptic properties of food fish are useful to identify consumer acceptance for freshwater fish varieties. This study focused on 02 objectives: investigation of present situation of inland fishery sector and identification of organoleptic aspects of major fishery resources in 3 selected reservoirs of Badulla District. Sorabora, Ulhitiya, Rathkinda reservoirs were selected for the study considering production levels based on secondary data. A survey was conducted using pretested structured questionnaire to collect the data on fish production, harvesting methods, fishing gears, and food fish varieties focusing on 122 fishermen in 3 reservoirs. Food fish sources with highest demand and production were subjected to sensory assessment. Gill net (3.5” mesh) was the prominent fishing gear, while “manna” (kind of harpoon) and “karaka” (cover pot) was used into lesser extent for harvesting fishes. All fishermen used nonmechanized fiberglass canoes (length 15.5ft-18ft) as most common fishing craft during fishing operations. Fish yields in reservoirs were affected by climatic variation. Nile Tilapia: Oreochromis niloticus accounts for >80% of total fish production with high demand (80%) in 3 reservoirs. Thus, sensory assessment was conducted for Nile Tilapia samples only. Mozambique Tilapia: Oreochromis mossambicus, Malkorali: Etroplus suratensis, Catla: Catla catla, Rohu: Labeo rohita, Mrigal: Cirrhinus mrigala and freshwater prawn: Macrobachium rosenbergii were minor contributors to the total harvest. Based on sensory evaluation, Nile Tilapia samples from Sorabora reservoir recorded highest consumer acceptance as complying with survey results. At present, more than 60% of fishing community in 3 reservoirs has not engaged with processing of value added products. Current study revealed the organoleptic aspects of Nile Tilapia flesh and data on freshwater fishery is useful as baseline information in fishery management programmes of Uva province.