Sri Lanka Journal of Aquatic Sciences最新文献

{"title":"Microplastics in beach sand and potential contamination of planktivorous fish Sardinella gibbosa inhabiting in coastal waters of Negombo, Sri Lanka","authors":"R. Ranatunga, D. Wijetunge, K. Karunarathna","doi":"10.4038/SLJAS.V26I1.7587","DOIUrl":"https://doi.org/10.4038/SLJAS.V26I1.7587","url":null,"abstract":"Microplastic pollution has become the most significant marine environmental concern. There has been a surge of information on microplastic contamination in various marine environments worldwide. However, the level of microplastic contamination in marine environments is just begun to understand in Sri Lanka. The present study looked at the microplastic contamination level in the beach sand of Pitipana, Catamaran, and Dūwana beaches along the coast of Negombo, Sri Lanka. Sampling was conducted bi-monthly from March to November in 2017. Beach sand samples were collected from the surface (0-1cm) and subsurface (10-11cm) layers and three regions representing the low-tide, high-tide, and vegetation line of each beach. Sand samples were filtered through 5mm and 1mm sieve-set, and particles greater than 5mm were discarded since they are not considered microplastics. Particles retained in 1mm sieve and the filtrate were collected separately. Microplastics were density separated and categorized into two size classes as 1-5mm and smaller than 1mm. Microplastics in the 1-5mm size-class were categorized as fiber, foam, fragment, and pellet. Microplastics","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"452 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75115486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Status of the fishery of Jaffna lagoon, Sri Lanka","authors":"N. Ragavan, D. Dissanayake, S. Kuganathan","doi":"10.4038/SLJAS.V26I1.7584","DOIUrl":"https://doi.org/10.4038/SLJAS.V26I1.7584","url":null,"abstract":"Jaffna lagoon (9° 50' N and 79° 50' E to 9°20' N and 80° 30' E) is the largest lagoon in Sri Lanka and it provides many services including fishing opportunities to the people in northern Sri Lanka. However, the status of the Jaffna lagoon fishery is not fully known at present due to the lack of detailed studies over the last 40 years. Therefore, this study was designed to fulfil this research gap. Both primary data and secondary data were used in this study. Primary data, including catch and fishing effort were collected at three major landing sites, Gurunagar, Paasaiyoor, and Kachchai by making fortnight field visits from March to December 2019. Secondary data of the monthly total catch and fishing effort were obtained from the district fisheries offices in Jaffna and Kilinochchi districts in order to estimate MSY and FMSY. This study revealed that ~5340 fishers confined to 39 landing sites were actively engaged in lagoon fishing during the study period using 12 different fishing methods. Fyke nets (71%) followed by stake nets (10%), lagoon seines, and lagoon boat seines (6%) are the widely used fishing methods in lagoon fisheries. Catch rates of major fishing gear were calculated and recorded as kg fisherman-1, day-1. Stake net (37kg ± 7) reported a significantly higher catch rate than fyke net (18kg ± 3), seine net (17kg ± 6), and crab net (16kg ± 3) (p<0.05; ANOVA). Both mechanized (59%) and non-mechanized (41%) crafts are used in the lagoon fishing practices. Forty-six commercially important finfish and shellfish species belonging to 25 families were identified in the lagoon catches of which Penaeidae made the highest percentage contribution (27%), followed by Siganidae (13%), Mugilidae (11%), Lethrinidae (10%), and Gerreidae (9%). Analysis of secondary data confirmed the increasing trend of fishing effort since 2009 but the total landings declined gradually after reporting its maximum value of 6958 Mt. in 2012. A rough estimate of maximum sustainable yield of the fishery of Jaffna lagoon was 6,694 Mt with the annual fishing effort (FMSY) of 1007 crafts. As the current fishing effort is higher than the FMSY, input control measures are recommended to utilize the lagoon fishery resources in a sustainable manner.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84180395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First records of three cepheid jellyfish species from Sri Lanka with redescription of the genus Marivagia Galil and Gershwin, 2010 (Cnidaria: Scyphozoa: Rhizostomeae: Cepheidae)","authors":"K. Karunarathne, M. Croos","doi":"10.4038/SLJAS.V25I2.7576","DOIUrl":"https://doi.org/10.4038/SLJAS.V25I2.7576","url":null,"abstract":"Cepheid medusae appeared in great numbers in the northeastern coastal waters of Sri Lanka during the non-monsoon period (March to October) posing adverse threats to fisheries and coastal tourism, but the taxonomic status of these jellyfishes was unknown. Therefore, an inclusive study on jellyfish was carried out from November 2016 to July 2019 for taxonomic identification of the species found in coastal waters. In this study, three species of cepheid mild stingers, Cephea cephea, Marivagia stellata, and Netrostoma setouchianum were reported for the first time in Sri Lankan waters. Moreover, the diagnostic description of the genus Marivagia is revised in this study due to the possessing of appendages on both oral arms and arm disc of Sri Lankan specimens, comparing with original notes and photographs of M. stellata.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"934 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85599710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Length weight relationship and diet composition of yellowfin tuna (Thunnus albacares) landed in Negombo Fishery Harbour, Sri Lanka.","authors":"H. Perera, P. Weerasiri","doi":"10.4038/SLJAS.V25I2.7579","DOIUrl":"https://doi.org/10.4038/SLJAS.V25I2.7579","url":null,"abstract":"Yellowfin tuna (Thunnus albacares) is the second most economically important tuna species in Sri Lanka. Present study was focused on the determination of length-weight relationship and analysis of stomach contents of yellowfin tuna landed in Negombo fishery harbour. A total of 174 stomachs of yellowfin tuna (Thunnus albacares) were analyzed. The total length range of the observed yellowfin tuna was 50-169 cm and weight range was 10-86.5 kg. The diet of yellowfin tuna comprised of a variety of food items such as fish (55%), squids (30%), crabs (6%), shrimps (8%) and others (1%) indicating that it is a non-selective predator. The observed length weight relationship for yellowfin tuna was W= 0.000104 TL2.6892.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87402120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First record of upside-down jellyfish Cassiopea andromeda (Forskål, 1775) (Cnidaria: Scyphozoa: Rhizostomeae: Cassiopeidae) from Sri Lanka","authors":"K. Karunarathne, S. Liyanaarachchi, M. Croos","doi":"10.4038/SLJAS.V25I2.7577","DOIUrl":"https://doi.org/10.4038/SLJAS.V25I2.7577","url":null,"abstract":"The circumtropical upside-down jellyfish Cassiopea andromeda is native to the Indian region, but no scientific documentations are confirming its presence in Sri Lankan waters. Hence in this paper, the occurrence of C. andromeda in Sri Lankan waters is reported for the first time. Species identification was based on several specimens collected from shallow waters of north and east coasts of the country in 2017. The C. andromeda found from Sri Lanka is a mild stinger and so far there are no reports on severe health issues cause to fishers and tourists. Also, this species was identified as a potential ornamental species due to its gorgeous appearance with very high colour variation.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"102 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85375106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Professor Sena S. De Silva (1946 – 2020)","authors":"Upali Sarath Amarasinghe, P. R. T. Cumaranatunge, M. J. S. Wijeyaratne","doi":"10.4038/sljas.v25i2.7575","DOIUrl":"https://doi.org/10.4038/sljas.v25i2.7575","url":null,"abstract":"","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78298315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gillnetting for small indigenous cyprinids in a Sri Lankan reservoir where culture-based fisheries are practiced","authors":"D. Athukorala, Upali S. Amarasinbghe","doi":"10.4038/SLJAS.V25I2.7578","DOIUrl":"https://doi.org/10.4038/SLJAS.V25I2.7578","url":null,"abstract":"In Sri Lankan reservoirs, small, indigenous fish species (SIS) are abundant and can be differentially exploited using small mesh (15-38 mm stretched mesh sizes) gillnets without any detrimental effects on the cichlid fisheries. However, in the recent past a paradigm shift in the reservoir fisheries of Sri Lanka is observed from total dependence on exotic cichlids to exploitation of exotic carps, stocked in reservoirs for the development of culture-based fisheries (CBF). As fingerlings of Chinese and Indian major carps and common carp are regularly stocked in reservoirs for the development of CBF, it is essential to investigate the potential impact of the use of small mesh gillnets to catch SIS on stocked fish fingerlings on CBF. In the present study, small mesh gillnets were used to exploit SIS during September 2011 to March 2013 when carp fingerlings were stocked in Chandrika wewa, Sri Lanka. The results revealed that no carp fingerlings (except 2 specimens of Indian carp species) were caught in any of the fishing trials with small mesh gillnets. As juvenile fish and stocked fish fingerlings occur in shallow littoral areas of reservoir, and as small mesh gillnets are laid at the depths ≥ 1.5 m, there is a habitat segregation of these two categories of fish. It is therefore possible to introduce a subsidiary fishery with small mesh gillnets to exploit SIS, which can co-exist with CBF in reservoirs of Sri Lanka.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73290000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sustainable Livelihood and Market Chain Analysis of Giant Freshwater Prawn Culture-Based Systems in Two Selected Reservoirs in Puttalam District, Sri Lanka","authors":"A. Abeyrathne, U. Jayasinghe-Mudalige, W. Wijenayake, M. Croos","doi":"10.4038/sljas.v25i1.7574","DOIUrl":"https://doi.org/10.4038/sljas.v25i1.7574","url":null,"abstract":"The Sustainable Livelihoods Framework, which identifies capital assets in five specific forms, including: (1) Human; (2) Social; (3) Physical: (4) Natural, and (5) Financial was applied to investigate the effects of production and marketing of giant freshwater prawn (Macrobrachium rosenbergii) from two reservoirs (Mahauswewa and Siyambalankatttuwa) in the Puttalam district in Sri Lanka on the livelihood of adjacent culture-based fishing (CBF) communities. Eighty different market actors selected through stratified random sampling techniques were subjected to a face-to-face interview with the help of a pre-tested structured questionnaire to collect primary information. The Livelihood Pentagons derived for each community suggest that, overall, the highest percentage (95.2%) is acquired by social capital followed by those of natural (74.5%); human (64.4%); physical (64.3%) and financial (58.2%). It was found that the potential of freshwater prawn markets to uplift rural livelihoods is not utilized commendably, because there are lack of information and poor coordination between and amongst the actors in market chains starting from fishermen to collectors and also with those traders involved in international/local markets.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80385052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of shelf life of Yellowfin tuna (Thunnus albacares) with regard to microbial count, histamine level and flesh colour","authors":"L. H. D. Hansamali, R. Ranatunga, P. K. C. Buddhinie, P. Ashoka","doi":"10.4038/sljas.v25i1.7571","DOIUrl":"https://doi.org/10.4038/sljas.v25i1.7571","url":null,"abstract":"Yellowfin tuna (YFT) (Thunnus albacares) is among the most popular fish in seafood trade all over the world. The quality of tuna meat is the main determinant of its market price. This study was conducted to determine the shelf life of YFT flesh stored at 0-2oC in terms of microbial total plate count (TPC), histamine levels and flesh colour change within 15 days of storage. Twenty-five YFT samples collected from a seafood processing factory, on the same day they received from the multi-day boats, were used in the study. In each visit, five fish samples were collected with the same catching date (5 days before landing). Samples were vacuum packed and taken to the laboratory where they stored under 0-2oC. All experiments were conducted on 1st, 4th, 7th, 11th, 14th and 15th days of storage. Pour plate method was conducted for total microbial plate count. Histamine content was determined using competitive ELISA method. Flesh colour change was determined by calculating the value of Red, Green, and Blue (RGB) colour ratios of the images using a colour detector mobile application. Results showed that the highest microbial count was exhibited on 7th day of storage and did not exceed more than 105 CFUg-1. Histamine levels were increased up to a maximum mean value of 14.24 ppm during the storage. Microbial counts and histamine results suggest that it is safe to consume YFT within 15 days under 0-2oC storage conditions.","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"106 1","pages":"1"},"PeriodicalIF":0.0,"publicationDate":"2020-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85746927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water quality parameters contributing to the invasion of water hyacinth (Eichhornia crassipes) in the Anawilundawa reservoir in Sri Lanka","authors":"M. Lekamge, M. Wijeyaratne, D. Dahanayaka","doi":"10.4038/sljas.v25i1.7572","DOIUrl":"https://doi.org/10.4038/sljas.v25i1.7572","url":null,"abstract":"Eichhornia crassipes has been found to invade the Anawilundawa reservoir located within Ramsar wetland in the northwestern region of Sri Lanka. Present study was carried out to determine the water quality parameters that could contribute to its invasion and identify an effective control measure. During the study period of March-November 2017, mean values for Secchi depth, water depth and nitrate content in areas where E. crassipes was present (7.9 cm, 12.4 cm and 475 µg L-1 respectively) were found to be significantly lower (p","PeriodicalId":21784,"journal":{"name":"Sri Lanka Journal of Aquatic Sciences","volume":"9 1","pages":"9"},"PeriodicalIF":0.0,"publicationDate":"2020-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87380759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}