Penaeus semisulcatus, the green tiger prawn, is an ecologically and economically important penaeid shrimp in the Indo-West Pacific region, especially in rice-shrimp farming and capture fisheries in Bangladesh and Sri Lanka, respectively. Genetic variation and phylogeography of samples of this species from Bangladesh and Sri Lanka were studied utilizing different mitochondrial DNA markers, i.e. cytochrome oxidase subunit 1 (CO1), control region (CR) and 16S rRNA genes. No evidence of population structure was observed in Bangladesh, but distinct variations were found among the Sri Lankan samples (Φ ST = 0.04, p = .002; F ST = 0.07, p = .001), with the western sample differing from the northwestern and southern samples. The Bangladesh population had lower genetic diversity than two of the three Sri Lanka populations. The phylogeography of P. semisulcatus revealed two distinct mitochondrial DNA (mtDNA) lineages, one in the Western Pacific Ocean and second in the Indian Ocean. The Bangladesh samples showed highest levels of similarity with samples from Sri Lanka, India and Malaysia, with the Bangladesh and Sri Lanka populations sharing the most common recent ancestry. Among the Indian Ocean samples, high levels of variation were observed in the samples from Iran, indicating admixture of two distinct mtDNA lineages, one shared by the populations from the Bay of Bengal and the other possibly originating from Eastern Africa. The genetic and phylogeographic information obtained in this study will be useful in appropriate planning for management and conservation of shrimp fisheries in Bangladesh and Sri Lanka, and in the Indo-West Pacific region. K E Y W O R D S 16S rRNA, Bangladesh, cytochrome oxidase subunit 1, mitochondrial control region, phylogeography, Sri Lanka 1

Processing and its impacts on proximate composition and fatty acid profile of six sea cucumber species; and sp. 1 collected from the northwest coast of Sri Lanka were analyzed. Sea cucumbers are processed into -- by both domestic and industrial level processors following the similar steps of cleaning, evisceration, first boiling, salting, second boiling and drying. However, domestically processed -- always reported a higher percentage of moisture, crude ash, crude fat and lower percentage of crude protein than industrially processed products. Although processing resulted in a significant reduction of total SFA and MUFA in fresh individuals of most of these species, total PUFA increased significantly in processed individuals excluding species. Palmitic acid was found to be the most dominant fatty acid in all these species followed by eicosapentaenoic acid, which showed a significant increase in processed products, except sp. 1. Total MUFA were higher than total SFA in all sea cucumber species having exceptions in sp.1 and fresh These findings will make a significant contribution to fill the gaps in existing information as no any previous information is available for species like and.

-The white shrimp (Fenneropenaeus indicus)is an ecologically and economically important penaeid species, widely distributed in the Indo-Pacific region. To obtain information on the genetic variation and population structure of F. indicus, sequencing analysis was conducted on a fragment of cytochrome oxidase subunit I (COI) of the mitochondrial DNA. Individuals (n = 217) from eight locations covering four main geographic regions along the coastal belt of Sri Lanka were analysed. The sequences, a 602-base pairs (bp) fragment in length, revealed high haplotype and nucleotide diversity that yielded 82 haplotypes. A mismatch analysis produced a unimodal distribution of pairwise differences between haplotypes, consistent with a historic rapid population expansion. Little or no genetic differentiation was observed between most samples, although genetic distances based on pairwise differences between haplotypes started to increase when geographic distances exceeded about 130 km. A population in Bundala (southeast) had lower diversity and was genetically differentiated from the others. This information could be important for the sustainable management and utilization of this resource.

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Lipid levels and fatty acid profiles in the flesh of wild caught and cultured Penaeus monodon were analyzed using, gas chromatography. The mean percentage lipid level of cultured P. monodon (3.9% ± 0 2 dry weight) was not significantly higher than that of the wild caught P. monodon (3.7% ± 0.1). The fatty acid profiles of wild caught and cultured shrimp were found to be significantly different from each other. The predominant fatty acids found in the flesh of both groups were Palmitic acid (16:0), Stearic acid (18:0), Oleic acid (18: ln-9), Vaccenic acid (18: ln-7), Linoleic acid (18:2n­6), Arachidonic acid-Omega-6 (20:4n-6), Eicosapentaenoic acid-Omega-3 (20:5n-3), and Docosahexaenoic acid-Omega-3 (22:6n-3). Total saturated fatty acids (38.12% ± 1.59) and polyunsaturated fatty acids (18.31% ± 1.57) contents were not significantly different in wild caught and reared P. monodon while monounsaturated fatty acid levels (44.82% ± 1.41) were significantly higher in wild caught P. monodon. Palmitoleic (C16:1), Heptadecenoic (C17:1), Myristoleic (C14:1), Vaccenic (C18: 1n-7), Hexadecatetaenoic (C16:4n-3), Alpha linoleic Omega-3 (C18:23n-3), Stearidonic (C18:4n-3), Docosatetraenoic (C22:4n-6), Docosapentaenoic (C22:5n-6) and Arachidonic Omega-6 (20:4n-6) contents were significantly high in wild caught shrimp, while Linoleic Omega-6 (18:2n-6) and Docosahexaenoic Omega-3 (22:6n-3) were significantly high in cultured shrimp.

Parapenaeopsis coromandelica shrimp populations along the western coast of Sri Lanka have supported coastal trawling for the last hundreds of years. Two non-overlapping adjacent fishing grounds (Hendala and Negombo) sustain different fishing intensities. In order to obtain information on the population structure and genetic diversity of P. coromandelica in these two regions, differences in length -weight relationships, growth, spawning seasons, sex-ratios, gonadosomatic index, length at 50% maturity (L 50 ) and sequence variation of the mitochondrial cytochrome oxidase subunit I were examined. Significant differences in population biology and genetic diversity were revealed from the two fishing grounds. Samples of Hendala showed lower L 50 and genetic diversity which are considered as potential effects and symptoms of extensive selective harvesting. Further, the shrimps' behaviour seems to be triggering the separation through low mixing of individuals at the two fishing grounds resulting in significant divergence based on haplotype frequencies. Management of P. coromandelica should consider the revealed biological and genetic evidences on existence of two sub-populations/stocks together with a routine monitoring of genetic effects due to harvesting.

Summary Catch statistics were monitored from well established small‐scale shrimp fisheries in Negombo lagoon and the adjacent coast in western Sri Lanka, in order to evaluate resource usage, gear selectivity, and spatio‐temporal dynamics of catches and CPUE. A total of 55 species, representing 35 families, including 13 shrimp species were recorded from 3546 samples obtained weekly during January 2009‐April 2010, for nine types of gear in six fishing grounds. Special emphasis was on shrimp catches: four main shrimp species, Metapenaeus dobsoni, Fenneropenaeus indicus, Parapenaeopsis coromandelica and Penaeus semisulcatus, represented 82% of the total shrimp landings. Catch per unit effort (CPUE) differed among fishing grounds, months and gear types. Species diversity differed among the gear chosen. Hierarchical cluster analysis based on presence‐absence of the species data of catches showed that clustering was based on habitat rather than on the fishing gear. Species composition analysed with a Detrended Correspondence Analyses over months and fishing grounds showed a distinction of trawl gear from the remainder of the gear operated in the lagoon. The information presented is of importance for evaluation of the present status of the shrimp fishery and for developing management strategies based on the types of gear.

Cepheid medusae appeared in great numbers in the northeastern coastal waters of Sri Lanka during the nonmonsoon 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.