The mud crab Scylla serrata is a highly exploited species, associated to mangrove ecosystems in the Indo-West-Pacific. It has a complex life cycle with a dispersing larvae phase, and benthic juveniles and adults. The former are stenohaline depending on high-salinity conditions to survive, whereas the latter are physiologically well adapted to changing temperatures and salinities, conditions that typically occur in mangrove habitats. Movement and habitat use of large juveniles and adults are well studied, and these life stages are known to utilize and move between various habitats within the mangrove ecosystem: intertidal flats as well as subtidal channels and flats. Females undertake long movements from brackish inshore waters to waters with oceanic conditions for spawning. Sensory abilities—of early stages and adult stages—have hardly been studied, and little is known about larval and early benthic stages in the wild. Summarizing, the literature revealed substantial gaps in the understanding of the spatiotemporal dynamics of the different life stages and of the clues that trigger recruitment, movement, and other behavior. This is the first comprehensive review on the life history, movement patterns, habitat use, and systemic role of S. serrata with emphasis on the respective life stages and geographic differences. We emphasize the need for further research into these processes as a basis for the sustainable management and conservation of this species.

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Life-history, movement, and habitat use of Scylla serrata (Decapoda, Portunidae): current knowledge and future challenges

The authors thank the Australian Centre for International Agricultural Research for providing partial funding for this project (PN 9217).

Seed Production of Mud Crab Scylla serrata Juveniles

Assessment of the effectiveness of mangrove rehabilitation using exploited and non-exploited indicator species.

Large and long-term investments in research, development and technology verification are required for the successful culture, domestication and coastal stock enhancement of any species, including crabs. As more species options are sought for culture, the choice of candidate species could be guided by ex-ante assessments to help identify suitable species and anticipate future constraints and opportunities. Focusing on tropical Indo-West Pacific Portunidae, we propose multiple criteria for domestication and stock enhancement that include life cycle, diet and feed conversion efficiency, behavior, disease resistance, growth rate, marketability, farming systems, profitability and environmental impact. The chief candidate species (four species of Scylla, Portunus pelagicus, P. sanguinolentus, and Charybdis feriatus) are considered against the criteria. Experience in the stock enhancement of P. trituberculatus, a subtropical portunid, is reviewed. We conclude that full domestication will not occur in the next 5 to 10 years and that the main constraints to be overcome are the aggressive behavior of the crabs, their carnivorous diet and competition for suitable coastal farm sites. We also recommend considering the tropical Portunus and Charybdis species examined here as additional or alternative options to the Scylla species. Stock enhancement may be feasible in some locations, provided suitable fisheries management and industry institutions are created.

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Choosing Tropical Portunid Species for Culture, Domestication and Stock Enhancement in the Indo-Pacific

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Lagoons of Sri Lanka: from the origins to the present

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Size at maturity and spawning periodicity of the mud crab scylla serrata (forskal) in the negombo estuary

The Mud crab, Scylla serrata is an economically important crustaceaninhabiting the lagoons of the west coast of Sri Lanka Currently there is interestin mass rearing of the species in ponds Thus, a study was carried out to identifythe food and feeding habits of Seylla serrata in the Negombo Lagoon Thestomach contents of crabs of different sizes caught by unbaited gears were screenedto identify the food constituents and it wasfound that crabs of medium size (subadults)mainly fed on molluscs and the small ones (juveniles) on crustaceansMonthly samples were also studied and found that there is no seasonal variationin the food items Diurnal studies were carried out to determine the feeding timeand it became evident that the crabs feed continuously during the night andonly at the high tide in the daytime

https://journals.sjp.ac.lk/index.php/vjs/article/view/1168/352

Food and Feeding Habits of the Mud Crab, Scylla serrata Forskal Inhabiting the Negombo Lagoon in the West Coast of Sri Lanka

The studies of two morphological and fifteen meristic characters of twelvespecies of Puntius showed that the most successful characters in separating'species were the counts of gill rakers, lateral line scales, vertebrae and pectoralrays. The other characters are less successful. The number of spines andrays of anal and pelvic fins are constant in the genus. Based on the 17 charactersstudied the twelve species of Puntius fall into three clusters: one containing'five species, the other containing two species and the third cluster with five':species. The species of the first two clusters were associated with higher meris-, tic characters, presence of barbels and complete lateral line. The species ofthe third cluster were associated with low meristic features and they werewithout barbels with the exception of one species with two barbels. Fourspecies of the third cluster contained with incomplete lateral line whilethe other one had a complete lateral line.

Interrelationships among the Species of the Genus Puntius (Teleostei, Cyprinidae) as Indicated by the Meristic and Morphological Characters

Three feeds were formulated using low cost raw materials with proteincontents ranging from 44% - 62% and prepared in the laboratory and weretested against an imported feed (protein 32%) on young stages (initial weight,0.03 - 0.71 g.) of four species of ornamental fish namely, Rosy Barb (Barbasconchoniusy, Angel (Pterophyllum scalurey; Gold fish (Carassius auratus auratus)and Goggle - eye iCarassius sp.) over a period of 2 months to assess thefeasibility of using locally prepared feeds in rearing of very young stages inornamental fish culture. High Assimilation Efficiencies (56 - 82 ~~), low Food Conversion Ratios(less thae 2), high Growth Rates (0.005) - 0.02 g. day") and high SurvivalRates (93% - 100) shown by all species on the prepared diets proved thelocally prepared feeds to be highly acceptable. The results also reveal that there is an optimal level of dietary proteinrequirement in the range of 44 - 50% for three of the four species studied. The study also showed that the cost of feeds can be reduced by (a) using low cost protein sources such as shrimp heads, fish/meatoffals, rice bran and soya flour; (b) using more carbohydrates with less protein.

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Growth Assessment of Some Ornamental Fish Species Fed with Low Cost Feeds

There are 55 species of fin fishes belonging to 33 families in the Bolgoda Lagoon, of which about 30 are commercially important. Sardinella melanura, Caranx sansun, Leognathus. sp, Mugil cephalus, Etroplus suratensis and Trachysurus cae/us are the dominant species. The mean annual fin fish production is 30 mt/year and it is on the decline.

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J. Jinadasa

Papers

Size at maturity and spawning periodicity of the mud crab scylla serrata (forskal) in the negombo estuary

Food and Feeding Habits of the Mud Crab, Scylla serrata Forskal Inhabiting the Negombo Lagoon in the West Coast of Sri Lanka

Interrelationships among the Species of the Genus Puntius (Teleostei, Cyprinidae) as Indicated by the Meristic and Morphological Characters

Growth Assessment of Some Ornamental Fish Species Fed with Low Cost Feeds

Species Composition, Distribution and Economic Importance of Fishes in the Bolgoda Lagoon