Browsing by Author "Gayathry, L.D."
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Item Comparative Study on Ring Net and Bottom-Set Gillnet Fisheries in Thalaimannar Pier, Sri Lanka(Uva Wellassa University of Sri Lanka, 2020) Kulas, J.A.J.F.; Wickramaratne, I.U.; Sosai, B.M.K.; Gayathry, L.D.Thalaimannar Pier, Sri Lanka was dominant with Ring net (Surukku) and Bottom-set gillnet fisheries. Details with those fisheries were lacking in the literature. A comparative study of both fisheries in Thalaimannar Pier was vital towards sustainable exploitation of fishery resources. The study aims at determining Catch-Per-Unit-Effort (CPUE), catch composition, and supply chain analysis of selected species from two fisheries last October (2019) to early January (2020). Total catch was recorded to the nearest kilogram and effort in-unit kilograms per square meter (kgm-2 ). The total catch of fish species in ring & gill nets was recorded. Results showed ring net catch mainly comprised of finfish (97.8%), crustaceans (1%), mollusk (1%); 1.2% were non-target species. Bottom-set gillnet catch comprises of crustaceans (50%), finfish (25%), mollusk (20%), and echinoderms (1%). Portunus pelagicus was the major target species, nearly 43% of the total catch. Out of the total, 29% of the bottom-set gillnet catch was discarded as nontarget species. Gillnet produced more non-target species. Mean CPUE (kgm-2 ) and standard deviation of ring & gill nets were 0.205 ± 0.062 and 0.0711 kgm-2 ± 0.018 respectively. CPUE for ring net increased from Late-November to Early-January; for gillnet, it decreased from mid November to early January. Sardinella gibbosa showed 71.11% of the price difference from wholesalers to outside retailers and Pampus argenteus (only exportable species) showed 47% of it from fishers to exporters in the supply chain. Ring net was harmful due to comparatively high catch per unit effort which may lead to overexploitation of commercially important fish populations. Gillnet was also harmful due to the high catch of non-target species. The current study provides baseline information that paves the way for sustainable exploitation of the aforementioned fisheries. Keywords: Ring net & Bottom-set gillnet fisheries, Catch per unit effort, By-catchItem A Preliminary Study on Potentials of Seaweed Culture as an Alternative Livelihood for Small Scale Fishing Community in Southern Coast of Sri Lanka(Uva Wellassa University of Sri Lanka, 2020) Gayathry, L.D.; Silva, A.P.R.; Shanuke, D.S.; Wijethunge, H.N.S.; Egodauyana, K.P.U.T.; Dharmakeerthi, T.N.; Jayarathna, W.N.D.S.; Bambaranda, B.V.A.S.M.Large scale seaweed mariculture is widespread in many Asian countries for decades. But Sri Lanka is still in its infancy. Therefore, promoting seaweed mariculture as a commercialscale industry is an urged necessity. Seaweeds grow abundantly along the southern coast of Sri Lanka. Therefore, the study attempted to assess the socio-economic status of small-scale fishermen, the potentiality of using seaweed culture as an alternative livelihood, and awareness of fishermen regarding seaweed culture on the southern coast of Sri Lanka. Data were collected by key-informant interviews and questionnaire surveys from November 2019 to February 2020. Cluster sampling was used to draw a sample of 160 fishermen from 8 major landing sites. Results of the socio-economic analysis showed that 72% of fishermen were between the age group of 35 - 55 years. Due to the seasonality of fishing, 65% of fishermen are having below-average monthly income (LKR 12,000 - 15,000). In three landing sites, 25% of fishermen are seasonal fishers. But almost all fishers are active in other landing sites. In total, 90% of fishermen are interested in seaweed farming. Identified reasons for their interest in seaweed culture were, additional income (85%), manageable with fishing (65%), and women empowerment (58%). Results relevant to awareness on seaweed farming among fishermen 80 - 90% in four landing sites, 60 - 65% in two landing sites, and below 30% in the other two landing sites. Favorable environmental conditions, adequate workforce, and willingness to initiate seaweed culture were identified as potentials. Absence of proper mechanism to disseminate knowledge, financial support, and lack of knowledge on marketing were identified as constraints for the initiation of seaweed farming. Accordingly, knowledge regarding seaweed farming should be disseminated and effectively transferred. The overall results indicate greater potential to initiate seaweed mariculture as an alternative livelihood for small scale fishing communities in southern Sri Lanka. Keywords: Seaweed, Mariculture, Fishing community, Alternative livelihood, Southern coastItem Some Aspects of the Reproductive Biology of Dasyatis zugei (Paleedged stingray) in the Gulf of Mannar, Sri Lanka(Uva Wellassa University of Sri Lanka, 2019-02) Gayathry, L.D.; Abeygunawardana, A.P.; Jayawardana, J.M.D.R.; Jayamanne, S.C.Dasyatis zugei is one of the major non-target species caught in the bottom-set crab nets used for catching blue swimming crab (Portunus pelagicus) in Gulf of Mannar. This study aims to determine the length–weight relationship, size at first maturity and fecundity of D. zugei. In total of 1,404 individuals were collected from crab nets in two landing sites; Vankalai and Thalvupadu in Gulf of Mannar during the period of September - November, 2018. Disc Width-WD of all the individuals were measured to the nearest mm, body weight was weighed to the nearest gram and sex was determined. The state of maturity of gonads of females was identified through dissection and macroscopic examination of ovaries. Mean ova diameter significantly varied among females according to the different maturity stages (P<0.05). Sex ratio in the catch was 1:1.35 (M: F). Disc width of males ranged from 85-260 mm with a mean of 175.43±22.42 and females ranged from 110-220 mm with a mean of 167.27±17.55. The Disc width-weight relationship was analyzed by Simple Linear Regression using log transformed data and it showed Log W = -0.5923 + 2.364 log WD for male and Log W = -3.497 + 2.599 log WD for female. The results show negative allometric growth (b<3) for D. zugei. There was no significant statistical difference (P>0.05) in the male and female regression co-efficient. The size at first maturity was 166.5 mm for female D. zugei. Embryos were found only in females ≥ 160 mm of WD. The maximum fecundity was three embryos per female which is varied with the size of the female. This study reports the first findings on length- weight relationship and size at maturity of D. zugei in Sri Lankan waters.Item A Study of Stock Status and Size at Maturity of Dasyatis Zugei (Pale-Edged Stingray) in Gulf of Mannar (Mannar District)(Uva Wellassa University of Sri Lanka, 2014) Gayathry, L.D.Dasyatis zugei is one of the major non-target species caught in the bottom-set crab nets used for catching blue swimming crab (Portunus pelagicus) in Gulf of Mannar. This study aims to determine stock status, the length—weight relationship and size at maturity. In total 1,404 individuals were collected from crab nets in two landing sites; Vankalai and Thalvupadu in Gulf of Mannar during the period of September - November, 2018. Disc Width-WD of all the individuals were measured to the nearest mm, body weight was weighed to the nearest gram and sex was determined. The state of maturity of gonads of females was identified through dissection and macroscopic examination of ovaries. Mean ova diameter significantly varied among females, according to the different maturity stages (P<0.05). Sex ratio in the catch was 1:1.35 (M: F). Disc width of males ranged from 85-260 mm with a mean of 175.43±22.42 and females ranged from 110-220 mm with a mean of 167.27±17.55. The Disc width-weight relationship was analyzed by Simple Linear Regression using log transformed data and it showed Log W = -0.5923 + 2.364 log W D for male and Log W = -3.497 + 2.599 log WD for female. The results show negative allometric growth (b<3) for D. zugei. There was no significant statistical difference (P>0.05) in male and female regression co-efficient. The size at first maturity = was 166.5 mm for female D. zugei. Embryos were found only in females > 160 mm of WD. The maximum fecundity was three embryos per female and the stock status of D. zugei was determined as above limit reference point (Spawning potential ratio as 21%) but not in a state of sustainable utilization. This study reports the first findings on length- weight relationship and size at maturity of D. zugei in Sri Lankan waters. Keywords: Dasyatis zugei, Size at maturity, Stock status, Length-weight relationship, Non-target species