International Research Symposium of UWU-2018

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Breeding performance of Pterophyllum scalare (Angelfish) fed with enriched Daphnia magna
(Uva Wellassa University of Sri Lanka, 2018) Mohamed Rashath, M.R.; Coswatte, A.C.W.W.M.C.L.K.; Withanage, P.M.; Liyanage, N.P.P.
Ornamental fish industry is a popular and profitable trade in the world. The production cost of ornamental fish varies with the cost of fish feed. The objective of the study was to investigate the breeding performance of Pterophyllum scalare fed with enriched Daphnia magna. The live feed of Daphnia magna was enriched with culture media, contained 58% crude protein and artificial feed with 40% crude protein were used to feed Pterophyllum scalare brooders (body weight l0g - 27g) as treatment I and II respectively. Square cement tanks with a size of 0.45 x 0.45 m2 were used for each treatment with 4 replicates for 80 days experimental period. Average Temperature, pH, Dissolved Oxygen, and Alkalinity in the two treatments were maintained at 28 °C, 7.4, 6.9 ppm and 560 mg 1-1 respectively. Although the brooders spawned in both treatments, the relative fecundity was not significantly different (P>0.05). Other breeding performances such as fertilization rate, spawn recovery and spawning period have shown significant differences (P<0.05) between Treatment-1 and Treatment-11. Comparatively highest fertilization rate (93.19%) and survival rate (70.87%) were observed in the Treatment-1, whereas lowest (fertilization rate: 67.31%) (survival rate: 50.55%) in Treatment-11. Most of the eggs in the Treatment-11 remained immature. Highest breeding performance was resulted with enriched Daphnia magna when compared to artificial feed in Pterophyllum scalare. The results revealed that the nutritional quality of the live feed considerably influenced on the breeding performance of Pterophyllum scalare.
Comparative Analysis of Morphological Characters of Blue Swimming Crab, Portuntis pelagicus (Linnaeus, 1758) Populations of Western and North-Western Regions in Sri Lank
(Uva Wellassa University of Sri Lanka, 2018) Disnika, A.V.H.R.; Senevirathna, J.D.M.; Liyanage, N.P.P.; Jayamanne, S.C.
The blue swimming crab, Portunus pelagicus, is abundant in indo-west pacific regions and extremely contributes for commercial fishery industry. In Sri Lanka, this species is typically found in Western, Northern, North-Western and NorthEastern Coasts. Morphological studies of P. pelagicus are important to identify population clusters and distribution patterns. Hence, this study was conducted to identify morphological variations of blue swimming crabs collected from Puttalum and Kalpitiya areas of the North-Western coastal region and the Negombo area of the Western coastal region. A Total of 240 individuals, 80 from each site were analyzed using twelve morphometric parameters. Standardized morphometric measurements were subjected to Discriminant Function Analysis (DFA) to observe intra-specific variations. According to the results, two discriminant functions were derived with 63.8% and 36.2% of variance for function I and 2 respectively, while function 1 was predicted as the strongest component (P < 0.05). The length to width ratio of the major cheliped merus (MEL/MEW=0.71) and ratio between carapace width (including 9th anterior-lateral tooth) to carapace length (CW2/CL-0.59) were identified as highly contributing parameters for function 1 and 2 respectively. The overlapped group plots suggested that there was no intra-specific morphological variability among three populations. Based on the results, it can be suggested that all three P. pelagicus groups are morphologically similar and consider as one population. The length-weight relationships of crabs in all three sites recorded negative allometric growth (b<3). However, results need to be confirmed using molecular data. Results of the current study provide basic information which could be utilized when constructing management plans on fisheries and conservation for this economically important carb species.
Comparison of Blue Swimming Crab, Portunus pelagicus (Linnaeus, 1758) populations from Batticaloa and Trincomalee areas in Sri Lanka using Morphometric Parameters
(Uva Wellassa University of Sri Lanka, 2018) Soyza, W.A.D.; Senevirathna, J.D.M.; Liyanage, N.P.P.; Jayamanne, S.C.
Western, Northern and Eastern areas of Sri Lanka are famous for blue swimming crab fishery. However, very limited studies have been carried out to identify their population structure. This study investigated the utility of morphological characters to differentiate Portunus pelagicus populations of two different areas in eastern province of Sri Lanka. Samples were collected from Batticaloa (n=46) and Trincomalee (n=46) waters throughout its known geographic range. Twelve morphometric characteristics were measured up to nearest 0.01 mm. Discriminant Function Analysis (DFA) was performed to analyze significant intra-specific variations of two populations using standardized morphometric characteristics. The derived single discriminant function was totally accounted for 100% variance (Wilks' Lambda=0.74, P<0.05). The carapace width to carapace length ratio (CW2/CL) was recorded the highest canonical discriminant function coefficient (0.89), thus CW2/CL was selected as the most suitable parameter for the predicted model. The two centroids derived by DFA were 0.59 and (-0.59) respectively for the Trincomalee and Batticaloa, and predict the separation of two groups. According to the plotted graph, minimal overlapping between two groups was observed with possible variation between two populations. Two different allometric coefficients (b) were recorded as 2.92 (closer to isometric growth) and 2.76 (negative allometric growth) for Trincomalee and Batticaloa populations respectively. Hence, the results suggest that there is a possibility of having two P. pelagicus stocks in the 2 sites of the eastern part of the island. Changes of prevailing environmental conditions and habitat are the factors that lead to morphological differences of two P. pelagicus populations. Finding of this study is important for implementations of site-specific sustainable fishery management programs. Further, population genetic studies are recommended to confirm the results of the present study.
Determination of Geographical Variations of Heavy Metals in Swordfish (Xiphias gladius) and Yellowfin Tuna (Thunnus albacares)
(Uva Wellassa University of Sri Lanka, 2018) Digoarachchi, D.A.S.U.; Walpita, C.N.
Bioaccumulation of heavy metals in marine fish has emerged as a serious health concern in consumers and economic burden to fish exporters. Heavy metal concentrations of fish found in Sri Lankan fishery products may cause risks of border rejections and economic losses. However, data are yet to be available in this regard. Present study was conducted to explore geographical variation of heavy metal accumulation in the swordfish (Xiphias gladius) and Yellowfin tuna (Thunnus albacares). The heavy metal analysis data (Hg, Cd, As, Pb) were collected from two fish export companies in Sri Lanka. Cd, As, Pb metals were not detectable in samples. There were 302 mercury analysis data of swordfish during June to September, 2017 and 33 mercury analysis data of yellowfin tuna during January, 2015 to August, 2017. According to the collected secondary data, particular way points were traced using log sheets. Then using QGIS software, monthly heavy metal variations were mapped against fish species. Results showed that heavy metal analysis data concentrated in main 4 areas between 64°00'00.000"E70°00'00.000"E & 0°00'00.000"N-8°00'00.000"N,76°00'00.000"E-80°00'00.000"E & 0°00 '00. 000"N-8°00'00.000"N,88°00'00.000"E-92°00 '00.000"E & 14°00'00.000 "N18°00'00.000"N and 82°00'00.000"E-90°00'00.000"E & 6°00'00.000"N14°00'00.000"N.The results revealed that Mercury is the major heavy metal that accumulates in the Swordfish and Yellowfin tuna. According to EU standards, Mercury accumulation is higher in Swordfish that exceed 1ppm standard limit. Accumulation is highest in the fish harvested in the area of 64°00'00.000"E70°00'00.000"E & 0°00'00.000"N-8°00'00.000"N.Accumulating proportion to its harvest was 40.33% that exceeds 1ppm level. The next highest mercury levels were found in the 88°00'00.000"E-92°00'00.000"E&14°00'00.000"N-18°00'00.000"N and proportion to the total harvest was 10.81% which is greater than 1ppm.In conclusion, the fish caught from these two areas tend to have more Mercury contaminations than those of other areas, suggesting possible predictive modeling applications for heavy metal accumulations in fish.
Determination of Suitable Breeding Substrate for Redside Barb (Puntius bitnaculatus) in Captive Conditions
(Uva Wellassa University of Sri Lanka, 2018) Wajiramala, G.K.Y.; Mahaliyana, A.S.; Chandrarathna, W.P.R.; Jayamanne, S.C.
Redside barb (Puntius biniaculatus) is one of the most popular indigenous ornamental fish species, which commonly found in Sri Lanka. This species has been heavily collected from wild for aquarium trade and have a severe influence on the reduction of naturally available stocks. Development of captive breeding and larval rearing techniques are found as an effective strategy to increase commercially available stocks, which will also lead to ensure the sustainable utilization as a valuable resource. Hence, the objective of this study was to determine the suitable substrate for successful breeding of Redside barb in captivity. Three types of breeding conditions; gravels with aquatic plants, sand with aquatic plants, only aquatic plants were provided with stilled water in 60 cm x 30 cm x 30 cm size indoor glass tanks and three replicates for each treatment were used. Mature males with bright red colour stripe on their body and females which released yolked eggs, when slight pressure is applied on their abdominal region were selected as brooders for the experiment. Selected individuals were introduced into each tank at 2:1 male to female ratio. Completely Randomized Design was used as the experimental design and produced fry number was counted. Data were analyzed using one way ANOVA. Spawning was observed in all conditions and fry number varied significantly among three different substrates (p<0.05). The highest mean fry number was observed in the substrate of gravel with aquatic plants (195±20) compared to other 2 (fry number in the substrate which contain sand with aquatic plants: 77±39 and only aquatic plants: 33+33). Results of this study revealed that the most suitable breeding substrate for the Redside barb in indoor glass tanks was the substrate with a gravel bottom and aquatic plants.
Determination of the Appropriate ayza sativa (Rice) Straw Fertilizer Loading Level to Enhance Survival Rate of Catla calla (Catla) Post Larvae
(Uva Wellassa University of Sri Lanka, 2018) Maddumaarachchi, M.A.D.U.; Somarathna, K.M.D.M.; Liyanage, N.P.P.
Introduction of the Indian major carp species like Catla calla (Catla), Labeo rohita (Rohu) and Cirrhinus mrigala (Mirigal) has been resulted in a significant development in inland fisheries in Sri Lanka. Among these introduced fish species, Catla contributes to freshwater fish production in Sri Lanka significantly. One of the identified problems in Aquaculture Development Center, Udawalawa was lower survival rate of Catla post larvae at nursery stage. Hence this study was conducted to determine appropriate rice straw loading level to enhance survival rate of Catla post larvae reared in nursery tanks of 20 m2. The experiment was conducted using a Completely Randomized Design (CRD). A preliminary fertilizing procedure was done to determine a defenitive range (75-90 g m2 of dried rice straw) to conduct the experiment and the tanks were fertilized at above rates. Body weights and total lengths of post larvae were recorded at stocking and water quality parameters were recorded twice a day in each treatment. Number of survived post larvae in each treatment were recorded with the body weights and total lengths at the end of the rearing period. Recorded data were analyzed using one way ANOVA and Tukey test was used to compare mean values at 5% significance level. Total plankton count, survival rate, length gain and weight gain of post larvae were significantly different (p<0.05) among treatments. 80 g m-2 loading level of rice straw was the best treatment showing highest survival rate (66.6210.69), greatest length gain (159.0816.99 cm), maximum weight gain (2,5761176g) and highest mean value of total plankton count (54,9101646). Adequate amounts of planktons and proper water quality parameters act as major reasons for higher survival rate of Catla post larvae. Therefore, the loading rate of 80 g In-2 was found to be best among treatments for fertilizing Catla nursery tanks with rice straw to enhance survival rate.
Effect of Four Formulated Diets on Colour Enhancement of Platy Fish, (Xiphophorus maculates)
(Uva Wellassa University of Sri Lanka, 2018) Premawansha, K. K. K.; Coswatte, A.C.W.W.M.C.L.K.; Liyanage, N. P. P.; de Silva, M. P. K. S. K.
Skin colouration is one of the most important factors which determines the commercial value of ornamental fish. Pigmentation in the skin is responsible for different colouration of fish. Pigment enriched feed is a reliable method, because hazardous effect of fish is considerably reduced. Objective of this study was to determine the colour development of platy fish subjected to four different diets. Four formulated diets were prepared using autolyzed ground shrimp head, autolyzed ground crab shell, dried & ground carrot as supplements and control diet without supplement. Twenty-five percent (25%) supplement was used for each diet preparation and other ingredients were common to all formulated diets consisted of the rest of 75% in the diet. Additional 25% of fish meal was used instead of supplement in the control diet. Experiment was conducted using five-day old platy as 30 individuals /tank and each treatment was triplicated. Laboratory conditions were maintained at 26±1 °C of temperature under natural photo periods for 75 days. Fish were fed two times per day until satiation. Photographs were captured in every 2 week interval by a same person with the same camera (Canon EOS 1300D) at a distance of 5.5 cm and 90° of angle at same condition for colour comparison. Pigmentations in the platy fish of each treatment were compared using a Mathematical language function which is called image analysis. Collected data were statistically analyzed using one-way ANOVA at p<0.05 of significant level by SPSS 24 software. According to the results, colour intensity of the platy fish fed with the feed containing autolyzed ground shrimp shell were significantly different (0.192±0.005) from the other three diets. All three experimental diets with carotenoid pigments at different levels had enhanced the colour of the fish. Present study reveals that the autolyzed shrimp head supplement is a good candidate in improving the colour of the platy fish.
Effect of Methyltestosterone Treated Feed on Growth and Gonadal Histology of Red Blonde Guppy Fish (Poecilia reticulata)
(Uva Wellassa University of Sri Lanka, 2018) Sampath, S.N.T.I.; De Silva, M.P.K.S.K.
In ornamental guppy fish (Poecilia reticulata) industry, male fish has higher demand as they are more colourful and attractive than females. Female guppy could be sex reversed and masculinized by using androgenic hormones. Present study assessed the effect of Methyltestosterone (MT) on growth and gonad differentiation of guppy fish. Three diets used in the study (A, B and C) had similar ingredients in same proportions except in diet A. In diet A, twenty five percent of fish meal was replaced by autolyzed prawn shells. Methyltestosterone was added (100 ppm/ Kg) to diets A & B and diet C was the control of the experiment. Guppy fish (0.009g±1.66x104) was stocked in glass tanks of size 18"x8"x6" at 20 fish /tank. Each treatment was triplicated. Mean body weight of fish in each tank was measured once every two weeks. After 120 days gonads were preserved and histological sections were taken. Highest body weight gain (0.225g±0.007), relative growth (44.67±6.53), survival rate (80.0% 2,7.64) was observed in fish fed with diet C. Mean body weight gain of fish fed with diet C was significantly different (P=0.04) from fish fed with diet B indicating that MT exerts negative effect on growth. Male to female ratio in control group was approximately 1:3 and 100% males were observed in fish fed with MT treated feed. Testis of male fish in control group contained spermatozeugmata (SZ) which are regular shaped cysts with clearly distinguished and methodically arranged different stages of spermatogenesis, while masculinized female fish had a different gonadal histology with irregular shaped SZ having stages of spermatogenesis not clearly distinguished and not arranged methodically.
Effect of Raw Spirulina platensis Supplement on the Growth Performance of Guppy Fish — Red Blonde (Poecilia reticulata)
(Uva Wellassa University of Sri Lanka, 2018) Sarathchandra, M.A.D.P.I.; Mahaliyana, A.S.; Coswatte, A.C.W.W.M.C.L.K.; Jayamanne, S.C.
Aquarium fish industry in Sri Lanka has become a valuable source of foreign exchange recently. Guppy fish (Poecilia reticulata) ranks the highest (67%) market of ornamental, fresh water fish export sector in Sri Lanka. Spirulina platensis is one of the commercially important micro algae due to its overall nutritional qualities. The study was investigated the effect of dietary supplementation of different percentages of Spirulina platensis (5%, 10%, 15%, 20%, and 25%) on growth performance, Feed Conversion Rate and survival rate in guppy and were compared with commercial feed as the control treatment. Spirulina platensis were cultured using axenic batch culture method in Zarrouck's medium, under illumination with a photo period of 12 hours light and dark. Glass tanks (0.3 m x 0.15 m x 0.15 in) were used for each treatment with 3 replicates and 21 days old red blond guppy were reared with a stocking density of 10 fish/tank for 30 days. Fish were fed, twice per day at a rate of 10% of body weight for 60 days. Data were collected every 2 weeks interval and analyzed by One Way Analysis Variance (ANOVA). There were significant differences between all the diets in terms of average body weights (p<0.05). Average body weight was highest in treatment with 5% raw Spiruina platensis incorporated feed (0.45±0.090 and lowest in control treatment (0.36±0.13g). No significant differences were observed in weight gain and Specific Growth Rate (SGR) (p>0.05) according to the treatments. There were significant differences of Feed Conversion Ratio (FCR) among all the diets (p<0.05), while it was lowest in 5% raw Spirulina platensis incorporated feed (1.43±0.06) and highest in the control treatment (2.05+0.09). 100% survival rate was observed in all treatments. The study revealed that 5% raw Spirulina platensis dietary supplementation enhances the growth rate in guppy fish.
Fishery Independent Assessment of the Size on Maturity of the Palk Bay Blue Swimming Crab Fishery (Portunus pelagicus) in Jaffna District
(Uva Wellassa University of Sri Lanka, 2018) Manivannan, M.; Abeygunawardana, A.P.; Creech, S.; Jayamanne, S.C.
Blue swimming crab (Portunus pelagicus) fishery industry in Sri Lanka has become a valuable source of foreign exchange recently, developed following the end of civil conflict in 2009. Size on maturity is a key life history parameter of exploited populations, used in fishery management practices. The aim of this study was to investigate the size on maturity of Portunus pelagicus by using a standardized sampling approach for the Palk Bay fishery. Crab samples were collected from both stake net fishery and crab net fishery during September-November, 2017. Portunus pelagicus were sampled from bottom-set crab nets in Mandaitheevu, Thuraiyoor and Chattipulam. Portunus pelagicus caught in stake nets were sampled from Kurunagar and Pannai. The maturity for standard sample of female crabs were assessed for a series of length classes ranged at 40 inm-159 mm, to identify the size on maturity for Portunus pelagicus in Jaffna District in the Palk Bay fishery. 1,253 of total female crabs were sampled. Carapace width and weight of Portunus pelagicus were recorded and Excel solver was used to estimate the size on maturity. The results of size on maturity data collected from crab net fishery dependent data were then compared. The level of maturity and immaturity for crab net were 83% and 17% respectively. 10% and 90% maturity and immaturity level were recorded for stake net fishery. As results revealed, L50 was recorded as 110.41 mm and L95 was 130.87 mm for this stock. According to the results and dependent data analysis, there is an effect in size on maturity of Portunus pelagicus by different sampling approaches in Palk Bay Fishery.
Freshness identification of marketable frigate tuna (Auxis thazard) using physical and chemical parameters under market storage conditions
(Uva Wellassa University of Sri Lanka, 2018) Walpola, T.K.; Dias, P.C.S.; Senevirathna, J.D.M.; Liyanage, N.P.P.
Identification of freshness of fish in the market is crucial for marine food fish industry in Sri Lanka. Chemical and physical qualities of fish are changed in storage condition and affected on the freshness level in fish muscle. This study was focused to examine chronological changes of physical and chemical parameters of frigate tuna to assess the freshness under the normal storage condition in the marketplace. Fish samples were collected from the commercial catch of Valaichchena harbor and stored under -18°C of freezing condition, which provided the normal market condition according to the findings of questionnaire survey. Five fish samples were kept at room temperature (~25°C) for 6 hrs in each day and pH value, alteration of water holding capacity, fat content, protein level and quality index of general appearance of fish species were tested daily after six hours of period for one week. Reference points of each parameter were suggested based on the pH changes of five replicates as pH act as key indicator on quality deterioration. The quality index of general appearance was ranged at minimum of zero (fresh) - maximum of 20 (spoiled). During the one week of storage period with the condition applied in the marketplace, pH value, water holding capacity, protein and fat content of frigate tuna were reduced significantly (p<0.05). Average pH value of frigate tuna was changed significantly at the 4th day (5.69±.045) (p<0.05), hence the 3rd storage day was considered as the reference point of quality deterioration of fish. At the 3rd day, water holding capacity, fat, protein content and quality index of general appearance were 72%, 0.8 c/o, 20% and 6.2 respectively. Fish appearance was highly changed at the 6th day of the period having 15.6 index value. This study recommends avoiding consumption of frigate tuna after three days in normal market storage condition and web based consumer guide would be useful to identify freshness of fish.
Growth Performance of Black Tiger Shrimp (Penaeus inonodon) Based on Three Different Brood Stock Collecting Areas Handala, Beruwala and Mulathivu in Sri Lanka
(Uva Wellassa University of Sri Lanka, 2018) Ekanayake, E.M.H.Y.; Athula, J.A.; Atapaththu, A.M.D.N.S.; Ranathunga, R.M.N.P.K.
Seed production of shrimp aquaculture industry in Sri Lanka is totally depends on the wild captured brood stocks. Among the 17 recorded brood stock collecting areas; Handala, Beruwala and Mulativu areas are provided proportionally higher amounts of brood shrimps to the industry. This study was carried out to investigate the differences of the growth performances of the cultured shrimps in accordance to the collecting area of the brood stock to produce post larvae (PL). 15 days old PL pertaining to three different collecting areas including three replicates for each area were stocked in fiberglass tanks (6m2) with the stocking density of 266m-2. Water quality, feeding and other management practices were maintained almost equally in all culture tanks. Initial PL quality, initial & subsequent average total length and average body weight were measured weekly up to the end of the culture period of 45 days. Survival rates, instantaneous mortality and specific growth rates were calculated. Data were analyzed using one-way ANOVA (P<0.05) to determine significant differences of growth parameters. It was revealed that no significant difference (P>0.05) of the initial body length and weight of PL stocks collected from three different areas. Though, initial quality parameters of the PL according to the brood stock collection area were not different significantly, lowest PL quality was recorded as 83% from Mulativu area and both Handala and Beruwala were recorded as 94%. After the culture period, highest significant (P<0.05) average body weight (1.04±0.08g), average body length (36.811.23min), highest significant instantaneous mortality rate (5.33±0.66) and lowest survival rate (51.0±9.53) were recorded for the PL produced using brood stock collected from Mulathivu area. There was no significant difference (P >0.05) of the specific growth rate of the all cultured shrimps. Overall results indicated that, there was no significant difference between the PL producing from brood stocks collected in three different areas.
Identification of Factors affecting to the Blue Swimming Crab (Portunus pelagicus) Harvest in Eastern Province, Sri Lanka
(Uva Wellassa University of Sri Lanka, 2018) Infaas, A.A.F.S.; Liyanage, N.P.P.; Wickramaratne, I.U.; Jayawardana, J.M.D.R.; Dias, P.C.B.
The blue swimming crab; Portunus pelagicus is a tropical marine crustacean species, having higher demands in local and global crab market during last few decades. But, there are limited studies on present harvest of blue swimming crab industry in Sri Lanka. Hence this study was conducted to investigate the current status of Blue swimming crab fishery and factors affecting on the daily harvest of Blue swimming crab in the Eastern Province, Sri Lanka. Stratified and Random Sampling techniques were used to select the target and by catch fisheries from Ampara, Batticaloa and Trincomalee districts. Data associated with harvesting methods and practices of Blue swimming crabs were collected from 372 fishermen and 23 sellers using pre tested structured questionnaire. Collected data were statistically analyzed using Minitab 17 software and MS Excel. Multiple Linear Regression model was fitted to determine the main factors affected on the daily Blue swimming crab harvest. Descriptive statistical analysis suggested that majority of the fishermen in the Eastern Province used Gill net (94.7%), while less percentage of fishermen used Cast net (2.9%) and Trap net (2.4%). It was found that, in average 4.5 kg of daily harvest was obtained and average price of blue Swimming crab was Rs 271.69 per kg. Furthermore, results of Regression analysis revealed that there is a significant relationship in daily Blue swimming crab harvest with mesh size, length of net, depth of net and number of net pieces (p<0.001). Study concluded that improving these factors would increase the Blue swimming crab harvest in. Eastern Province of Sri Lanka and necessary attention needs to be given at policy making in future.
Identification of suitable hardening medium for micro-propagated Lagenandra thwaitesii species in the Tilapia based aquaponic system
(Uva Wellassa University of Sri Lanka, 2018) Jayasinghe, J.A.R.A.; Coswatte, A.C.W.W.M.C.L.K.; Senavirathna, J.D.M.; Liyanage, N.P.P.
Lagenandra thwaitesii consider as a threatened endemic ornamental aquatic plant in family Aaraceae. Micro-propagation is a tool for large scale multiplication of these plants. High mortality experienced in transferring of micro-propagated plantlets from the laboratory to the environment is a major limitation in the production of L. thwaitesii at commercial scale. Aquaponic system is used for growing of various plants as a new approach to harden micro-propagated aquatic plantlets. This study focused on examining an effective hardening medium for L. thwaitesii in an aquaponic system. Six weeks aged uniform samples of in-vitro rooted L. thwaitesii plantlets were hardened by 3 different media; coconut husk, clay bricks shards and river gravels. Tilapia fish waste was used as the fertilizer from the aquaponic system, while trickling down to each section with different hardening media. The performance of plantlets in each media were measured using survival and growth parameters (number of leaves, length of roots, shoots and leaves, width of leaves, wet weight of plantlets) during five weeks of hardening period. The collected data were subjected to multivariate analysis at P < 0.05 level. According to the results, characteristics of hardening media significantly affect on growth performance of L. thwaitesii. Highest average leaf length (24.18+0.582), leaf width (10.58+0.250), root length (87.05+5.15) and wet weight (0.83+0.05) were recorded in clay brick shard medium, while maximum average number of leaves (4.05+0.189) was recorded from gravel medium. The 100% survival rate was obtained in all the hardening media. Bricks play a vital role in cation exchange, which enhances the nutrients availability for plants by increasing the growth rate of plants. Hence, clay bricks shards medium was considered as the best substrate for hardening of L. thwaitesii in the Tilapia based aquaponic system. This novel trend in integrated aquaculture system is useful to overcome the practical problems in micropropagation of L. thwaitesii plants, as a valuable asset for ornamental aquatic plant industry.
Impact of Thermocline Variability on Yellowfin Tuna Catch Rates of Sri Lankan Long-Liners
(Uva Wellassa University of Sri Lanka, 2018) Sinhakula, S.M.B.; Rajapaksha, J.; Thushari, G.G.N.; Guruge, K.P.G.K.P.
Tuna fishery is an important source of income to Sri Lanka, having a greater potential for development. Yellowfin tuna: Thunnus albacares is a major species, exported to Japan and EU countries. Vertical migration of fish with changes in temperature is considered as an important parameter to ensure fishing efficiency, thus harvest of yellowfin tuna is associated with the thermocline layer and its seasonal changes. The objective of the present study was to investigate the influence of vertical structure of temperature on catch rates of longline fishery. Temperaturedepth recording sensors were used to understand the depth penetration level of hooks and associated temperatures, during the period from July 2012 to February 2014. Based on sensor data and catch records, fishing depth was determined by means of sag caused by slack of the main line in between two buoys. Thermocline variability was analyzed using oceanographic datasets obtained from Copernicus Marine Environmental Monitoring Service. Temperature vertical profiles were extracted from those datasets at each fishing positions and a 5-parameter sigmoid model was used to determine the thermocline properties. Most commonly, 6-9 hooks per basket have been used in longlines, while total number of hooks was 8001000. Buoy-lines and branch-lines were ranged between 20-30 m and 45-50 m, respectively. Based on the hooks per basket, the depth penetration level closer to buoy-line is -70 m and -100 In at the center of a basket. Sagging variability of hooks in a basket have shown a linear relationship (r2=0.9992) with the distance between branch lines starting from buoy-line to the middle of a basket. Catch per unit effort was ranged between 15-70 kg / 1000 hooks. Thermocline depths altered between 100125 m with variations of corresponding temperatures at 21-23 °C. The developed model is capable of predicting hooking depths, thus the longline configuration can be adjusted with thermocline information for successful fishing operations.
Potential use of the skin of Canthidermis maculata (Bloch, 1786) as a value added product — A preliminary investigation for a cheaper and greener method
(Uva Wellassa University of Sri Lanka, 2018) Williams, S.S.; Munasinghe, D.H.N.
Trigger fish, C. maculata is available in markets as a result of by-catch of tuna fishery industry. It possesses a unique rough skin which is removed while processing the fish. The aim of the current study was to investigate a cheap and easy method to treat the skin of C. maculata in order to use as a value added product. Traditionally used solutions for depigmentation and removing scales (i.e. mixture of Na2S and Ca(OH)2) was used and was not able to treat C. maculata skin. Therefore, this procedure was modified to treat the skin with scales. Depigmentation was carried out using 4% (based on weight of the skin) Na2S and it was able to create the patchy appearance on the skin samples. Two treatments were conducted to improve the quality of the samples. For treatment I, samples were immersed (1g per 1ml) for 3 days separately in fat liquoring agents such as pure coconut oil, castor oil and two prepared fat liquoring agents based on coconut and castor oils (oil + H2SO4, H3 PO4 + NaCI + NaOH). As treatment II, samples were immersed in egg yolk (5g per 1m1) for 10 minutes. According to the results, egg yolk was identified as the more appropriate agent, which improves the flexibility of the skin samples within the minimum time duration of 10 minutes compared to others. A colorless varnish layer was applied on treated skin samples to improve the appearance and the water proofing ability. All treated skin samples were kept in the room temperature for six months to observe the changes occurred. It was observed that the skin samples treated with Na2S and egg yolk were able to maintain its improved quality compared to others. A sample with 50 g weight was produced at the rate of 5/= LKR and it was used to prepare products of wallets, folders, part of shoes etc. Further improvements of samples are suggested using advanced technology. This cheaper and greener method could be used as an additional income source by practicing as a house hold industry.
Preliminary study of Infectious Spleen and Kidney Necrosis Viral (ISKNV) disease in Asian sea bass (Lutes calcurifer) using histopathological method in Sri Lanka
(Uva Wellassa University of Sri Lanka, 2018) Ekanayake, U.L.N.S.; Fouzi, M.N.M.; Wijesundera, R.R.M.K.K.; Senevirathna, J.D.M.; Kurukulasuriya, M.S.; Jayaweera, W.R.; Wanasinghe, W.M.L.A.; Sakajamary, V.
Infectious Spleen and Kidney Necrosis Viral (ISKNV) disease is causing mass mortality in both marine and freshwater fish. Detection of this disease is crucial due to confusing clinical manifestations with many other bacterial and viral diseases. Pathology is one of the old and promising method for confirmatory diagnosis. The present study was carried out to confirm the presence of ISKNV in the cultured marine fish: Asian sea bass by histopathological method. Twenty moribund fish samples of sea bass with the mean weight of 60±20g were collected from cultured ponds in Trincomalee and Chillaw. Fish were selected based on the clinical signs suspected for ISKNV such as dark coloured fish with apathy, abnormal swimming, loss of appetite, pale gills and petechial hemorrhages in the operculum, mandible, fin base and abdomen. Spleen, Kidney, Liver, Gill and Brain samples were fixed in 10% neutral buffered formalin (NBF) for histopathological analysis. The formalinfixed tissues were processed routinely, embedded in paraffin wax, cut at 4 pm, and stained with Hematoxylin and Eosin (H&E). Postmortem finding of the study documented the presence of pale liver, pale gills, splenomegaly and fin rot. Degenerative and necrotic lesions in the kidney (mainly tubular epithelia) were observed in 15 fish (75%). Inflammatory cell (granulocytes, macrophages and lymphocytes) aggregates were observed in 10 fish (50%), while 17 fish (85%) showed degeneration, necrosis and vacuoles in hepatocytes with basophilic intracytoplasmic inclusion bodies. Inflammation of the gills were also observed in 10 fish (50%). This is the first study reporting the presence of ISKNV in the cultured marine fish: Asian Sea bass in Sri Lanka. Further studies are needed to determine the pathogenesis and pathology of ISKNV in different species of fish.
Preliminary Study of the Elasmobranch Fishery in Valaichchenai, Sri Lanka
(Uva Wellassa University of Sri Lanka, 2018) Dharmakeerthi, T.N.; Wickramaratne, I.U.; Jayamanne, S.C.; Fernando, D.; Tanna, A.V.; Bown, R.M.K.
Sharks and rays are included within the sub class Elasmobranchii. Indiscriminate fishing techniques have resulted in the progressive depletion of their populations globally. In Sri Lanka, these fisheries are driven by demand for shark fins, mobulid gill plates, their fresh meat and dried fish. This study collected information on shark and ray landings to provide information for sustainable management practices. A questionnaire survey was conducted with 140 fishers and biological parameters (length, weight and maturity data) were collected from 123 shark specimens and 129 ray specimens in Valaichchenai (7°55.58', 81 ° 31.80'), in the Eastern Province of Sri Lanka. Results showed a female biased sex ratio for sharks. 11.76% of them were observed to be pregnant. From the male sharks, 16% were immature. For the rays, 40% were immature, comprising of 67% of females of which 3.44% were pregnant. The most abundant species with growth coefficients and condition factors were Carcharhinus brevipinna (1.25, 1.09), Carcharhinus limbatus (2.80, 0.83), Carcharhinus anzboinensis (2.36, 1.17), Mobula japonica (1.62, 1.47) and Neotrygon kuhlii (1.86, 1.98) respectively. All species showed a negative allometric growth, except Carcharhinus litnbatus and most of the species have shown condition factor greater than one. The questionnaire revealed that fishers were aged between 18 to 68 years (mean=37.55±11.23) and 64% of fishers stated that their fishing area is as far North as Jaffna, with offshore ranging from 10-700 km. There was no significant difference between attitudes on the awareness of rules and regulations with fishers of varying age groups, but propensity of crossing boundaries showed a significant difference (p<0.05) with age group. The results showed that some endangered species such as Sphyrna lewini and also vulnerable species such as, Mobula tarapacana were being caught and immature males & pregnant females were landed. These results indicate the need of proper implementation of management plans for sustainable utilization of these resources. Thus, conducting awareness programs, declaring restricted areas (nursery grounds) and optimum length at first capture are important for sustainable utilization of fishery resources.
Study of Growth Performance of Oreochromis niloticus (Nile Tilapia) Fed by Formulated Diet Incorporated with Phytase Enzyme
(Uva Wellassa University of Sri Lanka, 2018) Bandara, B.R.M.P.; Withanage, P.M.; Coswatte, A.C.W.W.M.C.L.K.; Athula, J.A.
Fish is highly enriched with nutrients and serve as a valuable source of protein. Major constraints faced by inland aquaculture industry of Sri Lanka are higher feed cost and less growth performance of fish. Nile Tilapia (Oreochroinis niloticus) significantly contributes to the inland aquaculture due to its high adaptability to different environmental conditions and high growth rate. Phytase enzyme incorporated feed increases the release of phosphorus from plant meals and enhance the digestion in fish. Present study was focused to determine the effect of Phytase enzyme incorporated artificial feed on growth performance of Nile Tilapia. Two treatments, Treatment 1 artificial feed with Phytase enzyme and treatment 2 without phytase enzyme were conducted in fiberglass tanks (3.14 m3) with 3 replicates. Artificial feeds were formulated with 39% of protein and 0.2 g kg-1 of Phytase enzyme. Nile Tilapia fingerlings (mean weight 5g±1) were stocked with a stocking density of 5 fish per tank and reared for 10 weeks. They were fed three times per day at 5% of body weight. The live weight and total length of fish were measured within two weeks intervals. The weight gain of treatment 1 (17.25g±4.65) and treatment 2 (15.31g±4.10) were significantly different (p<0.05). Feed Conversion Ratio (FCR) for treatment 1 and 2 were 1.87±0.046 and 2.20+0.241 respectively with no significant difference. There was no significant difference of Specific Growth Rate (SGR) of fish between two treatments. Survival rate of both treatments were 100%. Since Treatment 1 revealed the highest weight gain, Phytase enzyme incorporated feed could be recommended to obtain the high growth performance of Nile tilapia in aquaculture industry.
Study on Effects of Substrates for Captive Breeding of Dankolapethiya (Dawkinsia singhala)
(Uva Wellassa University of Sri Lanka, 2018) Walisundara, W.M.N.K.; Mahaliyana, A.S.; Jayamanne, S.C.; Chandrarathna, W.P.R.
Dankolapethiya (Dawkinsia singhala) is an endemic freshwater fish in Sri Lanka. This fish species has high ornamental value in export market and their natural stocks are diminishing day by day due to excessive collection by ornamental fish trade, and habitat degradation resulted by anthropogenic activities. Therefore, from the perspectives of the aquarium fish industry and conservation of the endemic fish species, captive breeding of this species is a good remedy. The objective of this study was to identify the ideal substrate under captive breeding environment. Four different substrate conditions created in cement tanks with size of 1.5 m x 0.75 m using coconut coir, sand, gravel and bare bottom and stocked fish at 2:1 male female ratio. Bottoms of the experimental tanks were fully covered with the selected substrates. Each treatment was triplicated. Height of the water column was maintained as 0.20 m. Breeding experiment was started, after 6 weeks of wild caught Dawkinsia singhala brooders' acclimatization period. Experimental tanks were observed closely for 7-14 days after commencement of the experiment and 63 individuals of fry were observed in the tanks with sand substrate condition. Out of four different substrates, captive breeding was only successful in experimental tanks with sandy bottom substrate, while spawning of Dawkinsia singhala was not successful (0%) in other experimental tanks. The study revealed that Dawkinsia singhala can be successfully bred under sand substrate condition in still water. This study will assist researchers to further develop captive breeding techniques for this species.

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