Now showing items 50-69 of 79

    • Oral presentation

      A new approach in intensive nursery rearing of penaeids. 

      Aquacop - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The need for a nursery phase between the hatchery and the growing pond to avoid mortalities of young postlarvae, and provide a better assessment of stocked animals is general in crustacean aquaculture.

      The Centre Oceanologique du Pacifique recently developed a new culture technique using strong aeration, no water exchange and no external filter or artificial substrates. The technique relies on the development of a phytoplankton and bacterial medium with both nutritive and purifying qualities. Early postlarvae (PL3) are grown for a month or less up to 0.1 g mean weight, in 10 to 100 m3 tanks, at densities of 1 to 10 individuals/ℓ. The mean daily growth rates are around 20% for Penaeus indicus, P. stylirostris and P. vannamei and only 12-15% for P. monodon. For all species tested, density has little or no influence on growth. The final survival rates are generally high.
    • Conference paper

      Nutrition of penaeid prawns and shrimps. 

      A Kanazawa - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Since Hudinaga succeeded in the artificial hatching and subsequent culture of larvae of the prawn, Penaeus japonicus, techniques for rearing this prawn from hatching to commercial sizes have been improved in Japan and applied to other penaeid species in Asian and other countries. The nutritional requirements of P. japonicus juveniles started to be investigated about 15 years ago. As a result, this prawn is found to require proteins, lipids, carbohydrates, minerals, and vitamins for normal growth, indicating the deficiency disease, poor growth, and high mortality when reared with diets lacking some nutrients. On the basis of this knowledge, compounded artificial diets are used practically for commercial production of P. japonicus as substitutes for traditional live food such as the short-necked clam and mussel.

      However, seed production of penaeids has depended on live food such as diatoms, Chlorella and Artemia. Mass culture of planktonic organisms not only requires much manual help and expensive equipment but also fluctuates with climatic conditions. Also, the nutritive value of planktonic organisms is occasionally variable and this makes the use of live food for mass culture restrictive. Therefore, the development of artificial diets for larval penaeids is one of the most important research areas in the field of penaeid culture. We have prepared microparticulate diets for larval penaeids for use both as substitutes for live food and for nutritional studies. In this presentation, I intend to deal with the overview of penaeid nutrition.
    • Oral presentation

      Nutritional value of marine yeast fed to larvae of Penaeus monodon in combination with algae. 

      EJ Aujero, E Tech & S Javellana - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Saccharomyces cerevasiae and Rhodotorula aurantica, two marine yeast species, were fed to Penaeus monodon larvae (N6 to M1) singly and in combination with Tetraselmis sp. and Chaetoceros calcitrans in varying proportions. Larvae fed combination diets gave survival rates comparable to or higher than those fed algae or yeast alone. Chemical analyses show that the yeasts have low fat, moderate protein and high carbohydrate content. They also contain essential amino acids but are different in the fatty acids found to be essential for prawns. When used in combination with algae, the nutritional value of the yeasts seemed to have been improved.

      The use of marine yeasts in larval rearing could reduce economic and technological inputs in the production of natural foods for larval rearing. They are cheaper and easier to mass produce. They can be grown to very high densities using cheap carbon sources like molasses, brown sugar and coconut water with added nutrients in relatively shorter periods of time.
    • Oral presentation

      Observations on the nauplii production from wild, cultivated and mixed populations of the blue shrimp (Penaeus stylirostris) 

      RA Mendoza - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Due to low nauplii production from cultivated broodstock and to minimize dependence on wild stock, an experiment was run in which four treatments, consisting of combinations of 400 adult blue shrimp (Penaeus stylirostris) from wild and cultivated (F6) populations, were applied (wild females and males, wild females and cultivated males, cultivated females and wild males, and cultivated females and males). Females were inspected every third day. Those observed with spermatophores were captured and transferred to individual 100-ℓ spawning tanks. Water was treated with EDTA and erythromycin phosphate. More than 300 individual spawns were evaluated within a 180-day period. To evaluate the nauplii production per female, an analysis of variance for a factorial arrangement (43 × 2) was conducted. The factors considered were: the abovementioned treatments, different ovarian maturation stages, adhesion of the spermatophore, and kind of spawning (complete or partial). The mixed populations had higher nauplii production than the cultivated broodstock. All the females were tagged around an eyestalk and examined for rematuration. Up to six rematurations per female were registered as well as a minimum of four days between successive spawnings for the same female. The effect of rematuration on the quantity of nauplii is discussed. Gonadosomatic index for wild and cultivated females is compared. Selective criteria for spawners are given.
    • Oral presentation

      Osmotic, total protein and chloride regulation in Penaeus monodon. 

      RP Ferraris, FDP Estepa, JM Ladja & EG de Jesus - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The osmotic, total protein and chloride ion regulation in two size groups (10 and 30 g) of Penaeus monodon Fabricius was investigated. Preliminary experiments showed that osmolality, total protein and chloride concentrations tend to become stable 24 to 36 hours after molting.Thus,hemolymph values 36 to 240 hours after sampling were not significantly different from each other. Based on these results, only 36 hours (or more) postmolt animals were sampled after transfer from control (32 ppt) to five test salinities (8, 16, 24, 32 and 40 ppt). Hemolymph samples were then taken 1, 2, 3, 5, 7 and 10 days after transfer. Results showed that in general, osmolality, total protein and chloride concentrations in the hemolymph did not vary with time within the same salinity.Both sizes exhibited hyperosmotic and hyperionic regulation in lower salinities and hypoosmotic and hypoionic regulation in higher salinities. The isosmotic values obtained were approximately 676 to 720 mOsm (24 to 28.8 ppt) for the 10 g, and 724 to 792 mOsm (26 to 28.5 ppt) for the 30 g size group. For chloride, the isoionic values ranged from 324 to 339 mM in 10 g prawns. Slopes of the regression lines of hemolymph osmolality versus salinity in 10 g prawns were not significantly different from slopes of similar regression lines in 30 g prawns. These results suggest that the ability to regulate osmotic and total protein concentration in the hemolymph is similar in the two size groups.
    • Conference paper

      Overview of penaeid culture in the Americas. 

      GJ Escobar - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The paper discusses the reasons behind the farming success of Ecuador, as well as the limitations associated with farming throughout the rest of the Americas. Emphasis is given to specific farming practices, management techniques, and physical design characteristics. Through improved techniques the farmer is approaching the point where he can reliably manage his crop size and harvest time as dictated by market trends and postlarval supply.

      Until recently, pond production has been characterized by relatively small-scale operations often experimental in origin. Due to the farming success in one country, production output has risen from 4,800 tons in 1978 to 23,390 tons in 1983. As evidenced by this dramatic rise in production, Ecuador is in a period of expansion and increasing technical awareness, the combined results of which have led it to become the production leader in pond-grown shrimp.

      The economic pull towards Ecuador is now slowly giving way to shrimp development in other parts of the Americas. Owing to the technical gains brought about by government programs, universities and private industries, shrimp farming has become a potential activity in many areas previously thought inadequate. Production methods have progressed from the traditional extensive method to sophisticated closed system raceways. All but the latter method are exemplified by the techniques used throughout Ecuador.

      Presently, Ecuador has in production 50,000 ha of ponds. Of these, 30,000 ha are farmed using the extensive method characterized by low cost and low output. The successful approach referred to as the semi-extensive method occupies approximately 15,000 ha. This style of farming, while requiring increased cost, leads to a proportionately higher production output. The third approach is the semi-intensive method under which an estimated 5,000 ha are in production. Increasingly higher production rates are being achieved through improvements in physical pond design, pond maintenance and preparation, feeding and fertilization regimes, technical management, and control.
    • Conference paper

      Overview of penaeid culture research: Impact on commercial culture activity. 

      Aquacop - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The paper gives a comprehensive review of the state of penaeid culture research, its impact on commercial activity, and the major research efforts required to solve remaining problems. After providing a brief historical perspective and describing the dominant penaeid species under culture, the paper discusses the major components or phases of a production system: constitution of broodstock and maturation, larval and postlarval rearing, pregrowing in nursery systems, and grow-out. The extensive, semi-intensive and intensive grow-out systems are described including applied research on fertilization, water management, feeding, etc. needed to support these systems.

      Artificial diets (pellets, microcapsules) in relation to basic nutritional requirements and diseases (nutritional, environmental or caused by pathogens) in the larval rearing, grow-out and other production phases, and their respective research priorities are discussed. Lastly, the need for fundamental research in shrimp physiology, digestion, ecdysis, maturation, hormones, pheromones and genetics to complement applied research is highlighted.
    • Conference paper

      Overview of penaeid shrimp culture in Asia. 

      P Kungvankij - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Marine shrimp farming is a century-old practice in some Asian countries. Past sluggish development of the industry is mainly due to the inadequacy of hatchery technology resulting in inconsistent and insufficient supply of shrimp fry hence offsetting large scale development of the industry. Recent success in hatchery techniques coupled with high market demand have generated world-wide interest in developing shrimp farms in Asia. This paper attempts to make an in-depth review of the various aspects confronting the development and expansion of the shrimp farming industry.

      The cultural significance of the various penaeid shrimps cultivated in Asia (Penaeus monodon, P. japonicus, P. indicus, P. merguiensis and P. orientalis) is critically reviewed in relation to other subtropical species such as P. stylirostris and P. van-namei successfully cultivated in South America. The major constraints confronting large scale cultivation of P. monodon and other commonly important species are discussed and research gaps outlined. Present status of hatchery techniques is discussed and the need for standardization of viable techniques for technology packaging and verification is highlighted to ensure reliable source of seed supply. The various problems in hatchery development, including development of artificial larval feeds, are emphasized. This paper attempts to compare the technological and financial inputs in high technology with traditional farming practices in the region. The grow-out technology in relation to farming intensity and level of investment are outlined with special reference to the socio-economic condition in Asia. The need to develop viable and appropriate shrimp farming technology within the technical and financial capabilities of the rural small shrimp growers is discussed.
    • Oral presentation

      Penaeid larval culture using microencapsulated diets. 

      DI Jones - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Whilst it has been possible for many years to feed postlar-val penaeids successfully on artificial diets, problems of nutrient leaching, particle breakdown, and water fouling have prevented the use of such diets for early planktonic larval stages. It has recently been demonstrated that the technique of microencapsulation may be used to overcome these problems. Live foods used for penaeid culture have been successfully replaced by microencapsulated diets, both in the laboratory and at the hatchery level. The technology has now reached the level at which dietary requirements of individual species can be met by the incorporation of specific nutrients. Capsules can be supplied to function either as complete nutrient delivery systems or as food supplements.

      The present paper reviews this progress towards the total replacement of live foods in penaeid culture, and assesses the results of recent culture trials.
    • Oral presentation

      A preliminary economic analysis for extensive and semi-intensive shrimp culture in South Carolina, U.S.A. 

      PA Sandifer & LL Bauer - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      South Carolina has some 28,500 ha of impounded coastal wetlands. These impoundments are remnants of the rice culture industry of the 19th century and are now of interest for waterflow management and possibly aquaculture. The purpose of this study was to evaluate and compare the potential for extensive commercial culture of shrimp in salt-marsh impoundments with that for semi-intensive production of shrimp in highland ponds.

      A hypothetical farm consisting of four 8-ha impoundments or ponds was chosen as the basis for the analysis, and it was assumed that only one crop of shrimp could be produced per year. Two alternative strategies for stocking the impoundments were evaluated: option 1, stock by natural recruitment via tide gates; option 2, stock at low density (25,000/ha) with hatchery-reared postlarvae. Highland ponds were to be stocked at a density of 75,000 PL/ha with hatchery-reared animals. Major fixed costs other than land purchase were considered, including renovation of existing impoundments by cross-diking to form 8-ha units and addition of extra tide gates. Estimates of annual and variable costs for postlarvae (where applicable), feed, labor, chemicals, pumping, supplies, vehicle use, mowing, interest, overhead, and miscellaneous items were also included in the analysis. Results indicated that extensive shrimp culture in salt water impoundments is likely to be a break-even or profitable activity for production levels of 90 kg whole shrimp/ha for stocking option 1, while option 2 would require yields of ≥225 kg/ha. In comparison, semi-intensive culture in highland ponds is likely to be successful if yields of ≥ 800 kg/ha are obtained. This preliminary analysis suggests that both extensive and semi-intensive culture of shrimp may be economically feasible in South Carolina, but this potential is as yet un-proven and shrimp aquaculture must be considered a high risk venture in this area.
    • Book | Conference publication

      Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, Iloilo City, Philippines, 4-7 December 1984 

      Y Taki, JH Primavera & JA Llobrera (Eds.) - 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Abstracts of the 78 papers presented at the conference are cited individually.
    • Conference poster

      The production economics of an integrated prawn hatchery-floating nursery project. 

      R Agbayani, N Franco, D Israel, D De La Peña & AT Young - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The paper aims to present an economic evaluation of an integrated prawn (Penaeus monodon) hatchery-floating nursery project using standard economic tools and methods of analysis. The data used in the analysis were taken from SEAFDEC AQD experience at the Batan, Aklan Research Substation hatchery-floating nursery project. The technical bases were gathered from researchers after the peculiarities of aquaculture vis-a-vis other business ventures in agriculture and industry were taken into consideration.

      The study shows that an integrated hatchery-floating nursery project is a profitable culture system. The rate of return on investment for this integrated project ranges from 29 to 47% while payback period ranges from 1.8 to 2.6 years. A separate economic analysis of a hatchery project and a floating nursery was also undertaken to determine the profitability of independently operating each subsystem. The analysis shows better results for the floating nursery subsystem as compared to the hatchery subsystem. Return on investment and payback period for the floating nursery range from 23 to 78% and 1 to 3 years, respectively, while those for the hatchery range from 20 to 36% and 2.3 to 3.7 years, respectively.
    • Conference poster

      Recruitment of postlarval penaeid prawns in the Vellar estuary, South India. 

      Ramasamy A. & AP Pandian - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The northern bank of Vellar estuary (Parangipettai, India) is ideal for postlarval penaeid prawn recruitment. The annual recruitment, distribution and the substratum preference of postlarval immigrants at three different stations in the estuary were studied in detail.

      Among the postlarvae of Penaeus, P. (Fenneropenaeus) indicus was dominant followed by P. (Penaeus) monodon, P. (P.) semisulcatus, P. (F.) merguiensis and P. (Melicertus) latisulcatus. In Metapenaeus, postlarvae of M. monoceros were abundant followed by M. dobsoni, M. affinis, M. bre-vicornis and M. lysianassa.

      Two peaks were observed in the postlarval penaeid prawn population. In P (F.) indicus and P. (P.) monodon, the primary peak occurred from January to April and the secondary peak from July to September. In M. monoceros and M. dobsoni, the primary peak was from March to May and the secondary peak from August to September. The postlarvae of P. (F.) indicus, P. (P.) monodon, M. monoceros and M. dobsoni were available throughout the year while the others were seasonal. The distribution of postlarvae in the estuary is related to the type of substratum, salinity and temperature. The postlarval population declined during the northeast monsoon (November-December) and in peak summer (May-June). Their abundance decreased in the lower salinity areas of the upper reaches of the estuary.
    • Oral presentation

      The response of Penaeus monodon juveniles to varying protein/energy ratios in test diets. 

      M Bautista - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The response of Penaeus monodon juveniles (0.71±0.11 g) to varying protein/energy ratios in test diets was determined. Purified diets consisting of different levels of protein, lipid and carbohydrates were formulated. Two sets of experiments were conducted with the following diet combinations: (1) 30, 30, 50% protein, 5, 10, 15% lipid and 0, 10, 20% carbohydrate and (2) 40, 45, 50% protein, 5% lipid and 20, 25, 30% carbohydrate. Protein and energy ratios ranged from 89-198 mg protein/Kcal while the energy values for all diets were 165-415 Kcal/100 g. The diets were given twice daily at 10% of the body weight.

      Results showed that a two- to three-fold increase was observed in the body weight of prawns fed with diet combinations of 40-50% protein, 5-10% lipid and 20% carbohydrate with energy values of 285-370 Kcal/100 g. Reduction in protein content of the diet from 50 to 40% while maintaining the total energy level (285 Kcal/100 g) resulted in a change in growth that was not significant. An increase in energy level, at constant dietary protein level, resulted in improved utilization of protein and feed conversion efficiency.
    • Conference paper

      A review of maturation and reproduction in closed thelycum penaeids 

      JH Primavera - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Commercially important penaeids of the closed thelycum group belong to five subgenera of the genus Penaeus — Penaeus, Fenneropenaeus, Marsupenaeus and Melicertus that are almost exclusively Indo-West Pacific and Farfantepenaeus that is predominantly Western Atlantic. Since the ablation of Penaeus duorarum more than a decade ago, the first for any penaeid, around 23 species have been matured in captivity, 17 of them belonging to the closed thelycum subgenera (P. aztecus, P. brasiliensis, P. californiensis, P. duorarum, P. esculentus, P. indicus, P. japonicus, P. kerathurus, P. latisulcatus, P. merguiensis, P. monodon, P. notialis, P. orientalis, P. paulensis, P. penicillatus, P. plebejus, and P. semisulcatus).

      The complete spectrum of controlled reproduction in penaeids covers maturation, spawning, hatching of eggs into viable larvae, and the production of postlarvae to constitute the next batch of broodstock. The full closing of the cycle has been achieved in at least six closed thelycum species whereas gaps, e.g. inability of mature females to spawn or nonhatching of eggs, remain for the others.

      Spawners or mature females used in commercial hatcheries and research laboratories are either wild-caught or matured in captivity with human control ranging from nil to a regular closing of the cycle. Wild spawners may be spawned directly after capture and transport or subjected to environmental manipulation, e.g. thermal control to induce or inhibit spawning. Females matured in captivity may come from wild broodstock (adults and subadults caught from estuaries or "sourced" by trawlers from offshore waters) or captive (pond- or tank-reared) broodstock. Introduced or exotic penaeid species must depend on a pond- or tank-reared broodstock whereas indigenous prawns and shrimps may be constituted from wild or captive broodstock.

      There are three basic approaches employed singly or in combination to induce ovarian maturation in penaeids — endocrine, dietary or nutritional and environmental. Endocrine manipulation has so far been synonymous with unilateral eyestalk ablation, a technique with far-reaching impact on penaeid aquaculture. Closed thelycum penaeids may be classified into those that require ablation in order to mature and those that do not. To a third group belong species that have been experimentally induced to mature with and without ablation.

      Diets for maturation include fresh and frozen animal sources (mussel, clam, oyster, squid, marine worms, shrimps, fish) and formulated pellets given in any combination. The choice of marine worms and mollusks is based on their high levels of arachidonic, eicosapentaenoic and docosahexaenoic acid, the dominant fatty acids found in mature ovaries and testes. Environmental parameters studied in relation to maturation include light (intensity, quality and photoperiod), temperature, salinity and pH.

      Although a regular closing of the cycle has been achieved for some, the state-of-the-art for most penaeids is the successful production of larvae and postlarvae from either wild spawners or wild immature/spent females matured/rematured in captivity. The improvement of reproductive performance including larval quality from captive broodstock remains a major area for future research and includes the determination of minimum age and size for maturation. The complete description of the nutritional and environmental requirements for maturation should lead to the development of alternatives to ablation such as photoperiod manipulation or the use of reproductive hormones.

      The present focus on characterizing the physicochemical and dietary requirements for maturation should be extended to other phases of reproduction: mating, spawning, fertilization and hatching. Studies on biology (molting, mating, fertilization including the cortical reaction) and biochemistry (maturation stages) provide baseline information for designing maturation tanks and formulating broodstock pellets. Investigations of wild stocks complement laboratory studies in elucidating the interrelationships among molting, mating, maturation and spawning.

      Manual spermatophore transfer is being developed to solve the problem of nonmating in closed (and open) thelycum species. This technique will also be useful in future hybridization work, together with in vitro fertilization.
    • Conference paper

      A review of the diseases of cultured penaeid shrimps and prawns with emphasis on recent discoveries and developments. 

      DV Lightner - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The development of the commercial culture of penaeid shrimps and prawns has been accompanied by the occurrence of diseases of infectious and noninfectious etiologies. Many of the important penaeid diseases are caused by organisms that are part of the normal microflora and fauna of penaeids. These organisms are opportunistic pathogens that cause disease only under conditions that favor them over the host. Many organisms in this category are ubiquitous, and most have been recognized and/or reported from each of the major penaeid culture areas of the world. Included among this category of pathogens are the filamentous bacteria Leucothrix mucor, Flexibacter sp. and Cytophaga sp. (agents of filamentous gill and surface fouling diseases); the peritrich protozoans Zoothamnium sp., Epistylis sp., and Vorticella sp. (surface epibionts that cause protozoan gill disease and surface fouling diseases), the invasive bacteria Vibrio alginolyticus and V. parahaemolyticus (agents of various bacterial disease syndromes); and the fungi Lagenidium callinectes, Sirolpidium sp., and Fusarium solani (agents of the most common fungus diseases of penaeids).

      Among the most important disease-causing agents are the penaeid viruses. These penaeid viruses may once have been limited in their geographic distribution in wild stocks, but they have become widespread in penaeid culture facilities. With the advent of commercial penaeid hatcheries, the shipment of broodstock and postlarvae from these culture facilities to others in different geographic regions has often resulted in the spread of these agents outside their normal range in wild populations. Included in this category of the penaeid viruses are the baculoviruses: Baculovirus penaei (BP), P. monodon baculovirus (MBV), baculoviral midgut gland necrosis virus (BMN); the hepatopancreatic parvo-like virus (HPV); the probable picornavirus infectious hypodermal and hematopoietic necrosis virus (IHHNV), and a reo-like virus in P. japonicus.

      The final group of important diseases of cultured penaeids are the nutritional, physical, and toxic disease syndromes. The ascorbic acid deficiency syndrome called "black death" is the best understood nutritional disease of penaeids. Among the physical diseases occurring in penaeid culture, gas bubble disease and tail cramp are probably the most common. Important toxic disease syndromes include aflatoxicosis and red disease (which may be due to mycotoxins); hemocytic enteritis (due to certain species of filamentous blue-green algae, especially Schizothrix calcicola) and toxic syndromes due to toxic algal blooms.

      There are five areas of research that should receive emphasis in the next several years in penaeid disease research: 1) Appropriately equipped laboratories in each of the major penaeid culture areas should identify and catalog those diseases occurring in culture facilities in their region; 2) Penaeid diagnostic laboratories should use, or strive to develop for general use, "standardized" diagnostic procedures whenever possible, especially for highly infectious agents such as the penaeid viruses; 3) Penaeid cell culture methods for primary cultures or cell lines must be developed to aid in the development of much needed rapid, sensitive diagnostic tests for the penaeid viruses; 4) Improved methods of disease prevention, control, or chemotherapy are needed for many of the penaeid diseases now adversely affecting the penaeid culture industry; and 5) Approval is needed from those government agencies (such as the U.S. Food and Drug Administration and the Environmental Protection Agency) for the drugs and chemicals used as chemotherapeutics in penaeid culture that may pose a health risk to humans.
    • Oral presentation

      Role of bacteria and meiofauna in the productivity of prawn aquaculture ponds. 

      DJW Moriarty - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Detrital food chains, based on the use of manures and compost have been used in aquaculture for centuries. Heterotrophic bacteria convert organic detritus into protein and thus constitute an important food source in ponds. Bacterial growth rates, and thus productivity, in natural environments can be calculated from the rate of tritiated thymidine incorporation into DNA. Rates of oxygen consumption by bacteria can be estimated from values for production. The tritiated thymidine method has been used to measure bacterial production in aquaculture ponds where a pelleted food was fed to penaeid prawns. It was found that most of the pelleted food was supporting bacterial growth, with bacterial production ranging from 0.43 to 2.1 mgCℓ–1d–1 in the water and 150 to 500 mgC m–2d–1 in the sediment. Bacterial biomass and growth rates were shown to be regulated by meiofauna, which in turn were eaten by the prawns. Primary production was not significant in the ponds. More oxygen was consumed by bacteria in the water column than was produced by photosynthesis of phytoplankton.

      Average shrimp yields at harvest were: chicken manure, 262 kg/ha; cow manure, 218 kg/ha; feed, 387 kg/ha; and control, 160 kg/ha. Average survival for each treatment was 50, 76, 58 and 79%, respectively. The percent yield of P. vannamei: P. stylirostris: P. occidentalis by weight for the four treatments was 85:15:0, 87:13:0, 78:22:0, and 92:9:0, respectively. P. occidentalis suffered 100% mortality during the production period. Average weights of shrimp at harvest were 8.72, 7.32, 12.07, and 5.98 g for the respective treatments. Ratios of average individual weights for P. vannamei: P. stylirostris for the treatments were 2.00:1, 1.99:1 and 2.22:1, respectively. Manures and feed significantly increased yield over the control (P< .0002). Feed significantly increased yield over that of the manures (P < .0001); while yields for manures did not differ (P > .05). Survival was not significantly different among treatments (P > .05).
    • Conference poster

      Ruppia maritima and Najas graminea as natural foods for Penaeus monodon juveniles. 

      RQ Gacutan & J Primavera - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Ruppia maritima (kusay-kusay, Hiligaynon) and Najas graminea (digman, Hiligaynon) are macrophytes growing in local brackishwater ponds believed to provide food and shelter to prawns and fishes. Their effect on growth and survival of Penaeus monodon juveniles (PL50; carapace length, 4.01 mm; body weight, 0.053 g) were studied in 80-ℓ glass aquaria. The treatments were: (a) a commercial pellet (40% protein); (b) live Ruppia; (c) decaying Ruppia; (d) live Najas; and (e) decaying Najas. The pellet was offered to satiety (approx. 100% of body weight) twice daily. Live Ruppia and Najas were transplanted in the aquaria using pond soil a week prior to the experiment. Decaying Ruppia and Najas were transferred from ponds. Salinity was maintained at 15 ppt and 50% of the water was changed regularly.

      Highly significant differences (P < 0.01) in mean carapace length (CL) and mean body weight (BW) on the 10th, 20th and 30th days were observed among treatments. Increase in CL was fastest with decaying Najas and slowest in live Ruppia (14% vs. 17% after 30 days). Growth with decaying Ruppia was comparable to pellets on the 10th and 20th days but was faster after 30 days. Body weight on all sampling days was highest in decaying Najas and lowest in live Ruppia. Percentage increases were 122, 273 and 565% on the 10th, 20th and 30th days, respectively, with decaying Najas. Those given live Ruppia registered increases of 11, 67 and 94%, respectively. The rapid growth rate of animals on decaying Najas was compensated negatively by a low survival rate (31%), significantly lower than on live Najas (100%). Other survival percentages were: decaying Ruppia, 59% and pellet, 53%.
    • Conference poster

      Seasonal abundance of Penaeid prawn seed in the Ennore estuary, Madras in relation to hydrography and lunar phase. 

      S Vasudevan & T Subramoniam - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      An estimate of seed resources in the coastline, estuarine, and backwater bodies is an important prerequisite for developing prawn farming. A one-year (1983) survey on penaeid seed, based on tide and lunar periodicity, indicates the following species: Metapenaeus dobsoni, Penaeus indicus, P. japonicus, M. monoceros, P. semisulcatus and P. monodon in order of their abundance. P. indicus and P. japonicus are predominant in February and March (77.5 and 82.06% of total seed, respectively) when the average salinity ranges from 33.6 to 35.1 ppt followed by M. dobsoni. A second peak of P. indicus is observed in June when M. dobsoni showed its highest peak (47.35%) with continued abundance up to December.

      During the northeast monsoon, when the average salinity fell to a lower range of 19.9 to 24.6 ppt, P. monodon and M. monoceros showed moderate abundance. As the site chosen is very near the bar mouth, most of the seed collected were postlarvae. In Penaeus and Metapenaeus genera, total size range is 7-15 mm and 3-4 mm, respectively. Afternoon collections showed greater abundance followed by forenoon and night collections. Low tide and Full Moon collections showed greater abundance than those made during high tide and New Moon. Differences in seasonality may reflect breeding intensity of the respective prawn species in the sea. Variations in hydrographic features may also significantly contribute to seasonal abundance. A strong correlation between salinity and seed abundance is seen. The seed potential of these prawns in Ennore estuary is discussed.
    • Conference poster

      Seasonal and local occurrence of adults and postlarval stages of Penaeus merguiensis and Penaeus indicus in Batan bay, Philippines. 

      VC Bañada - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Studies on seasonal and local occurrence of adults (spawners) and postlarval stages of Penaeus merguiensis and P. indicus in Batan Bay and Banate Bay, Aklan yielded the following results: 1) small-sized P. merguiensis and P. indicus dominated the rivers and interior bays, 2) P. merguiensis and P. indicus spawners appeared throughout the year with varying monthly abundance in Batan Channel and Banate shoreline, and 3) larval stages of penaeids were found in interior bays but were more abundant in the channel and offshore areas. Postlarval stages of penaeids are more abundant along the shoreline than in water edges of mangrove swamps which indicate that channels and offshore waters may be primary spawning grounds while interior bays and rivers are secondary spawning grounds. Moreover, size distribution of carapace length of P. merguiensis suggests that the channel and offshore areas are utilized as primary spawning grounds while the inner portions of the bay are nursery grounds and secondary spawning grounds.

      Lunar phase did not show a positive correlation with abundance of both spawners and postlarval P. merguiensis and P. indicus. The minimum size at sexual maturity for both male and female P. merguiensis is about 11 mm CL. Female P. indicus appear to become sexually mature at a smaller size (13 mm CL) than males (20 mm CL).