Now showing items 1059-1075 of 1075

    • Article

      Water hardness determination using local laundry bar soaps for carp hatcheries. 

      JM Ferriols-Pavico, EV Aralar & AC Gonzal - Fisheries Research Journal of the Philippines, 1988 - Fisheries Research Society of the Philippines
      A simple method using local laundry soap is described for carp hatchery operation. A saturated soap solution was prepared and uses to titrate a 100-ml water sample of known hardness until a permanent lather appeared on the surface of the sample. The volume of soap solution was recorded to correspond to the hardness level tested. A fish farmer’s guide on the approximate levels of water hardness using WHEEL or PERLA soap solution is provided.
    • Article

      Water quality and holding capacity of intensive and semi-intensive milkfish (Chanos chanos) ponds 

      NS Sumagaysay-Chavoso & ML San Diego-McGlone - Aquaculture, 2003 - Elsevier
      This study determined the holding capacity of semi-intensive and intensive milkfish ponds and water quality in relation to fish biomass and feed input. Six units of 1000 m2 brackishwater ponds were used, three ponds for intensive system (20,000 fish ha−1) and three for semi-intensive system (8000 fish ha−1). Average production was significantly higher in intensive pond (3652 kg ha−1) than in semi-intensive pond (1352 kg ha−1) after a desired marketable size of fish was reached. Highest concentrations in effluents (mg l−1) of rearing water measured every 2 weeks were 0.369 and 0.289 for chlorophyll a (chl a), 0.485 and 0.512 for PO4–P, 0.279 and 0.811 for TAN, 0.094 and 0.082 for NO2–N, and 14.040 and 8.649 for NO3–N, 216 and 142 for total suspended solids (TSS), 15.0 and 21.7 for biological oxygen demand (BOD), in intensive and semi-intensive ponds, respectively. Lowest morning dissolved oxygen (DO) in intensive pond was 2.2 mg l−1, and did not decrease further because of aeration. In unaerated, semi-intensive pond, morning DO ranged from 1.3 to 5.0 mg l−1 but occasionally went below 1.0 mg l−1 resulting to fish mortalities at biomass of 835, 1206, and 1489 kg ha−1. Levels of NO3–N and dissolved inorganic N are linear functions of fish biomass or feed input in all systems (P<0.05). The buildup of nutrients is more pronounced at biomass of 1610 kg ha−1 and above while nutrient transformation (conversion of PO4–P or TAN to phytoplankton or vice versa) is apparent at biomass below 1419 kg ha−1. The holding capacity of unaerated, semi-intensive pond is below 1348 kg ha−1 or 54 kg feed ha−1 day−1 based on DO concentration of less than 1.0 mg l−1. However, the holding capacity can be lower than 835 kg ha−1 or 33 kg feed ha−1 day−1 during very calm weather or during rainy days when water column is stratified. Based on the results of regression analysis, the holding capacity of intensive pond should be set below 5107 kg ha−1 or 110 kg feed ha−1 day−1 so as not to exceed the acceptable levels for water quality variables in effluent waters.
    • Article

      The way forward with ecosystem-based management in tropical contexts: Reconciling with existing management systems 

      This paper discusses some of the challenges and opportunities that can arise when implementing ecosystem-basedmanagement (EBM) in tropical nations. EBM creates a new series of challenges, problems, and opportunities that must be considered in light of existing governance and management frameworks in a local context. The paper presents five case studies from different parts of the tropical world, including Oceania, insular and continental Southeast Asia, East Africa, and the Caribbean, which illustrate that the implementation of EBM in watershed and marine ecosystems offers a new series of challenges and opportunities for its inclusion with existing forms of environmental governance and management. The paper suggests that EBM is best thought of as an expansion of customary management (CM) and integrated coastal management (ICM), rather than a paradigm shift, and that it has certain benefits that are worth integrating into existing systems when possible. The paper concludes that the cultural and institutional context of CM as well as the experience, technical skills, and legal basis that serve ICM programs are logical platforms from which to build EBM programs. Some guidelines for creating hybrid management regimes are suggested. In sum, declining marine species and ecosystems require urgent action, necessitating utilization of existing paradigms such as ICM and CM as a foundation for building EBM.
    • Article

      Weaning of hatchery-bred milkfish larvae from live food to artificial diets 

      M Duray & T Bagarinao - Aquaculture, 1984 - Elsevier
      Two-week old milkfish (Chanos chanos ) larvae (7.5 mm standard length, 2.3 mg wet body weight) previously fed only rotifers were weaned abruptly to six artificial diets (commercial feed TP, artificial plankton AS and BP, experimental SEAFDEC diets CT and CB, and moist egg diet) with control larvae fed Artemia nauplii. Survival rates ranged from 38% on moist egg diet to 63% on BP, with 42% in the control. On day 43, larvae attained mean lengths of 7.7 mm on moist egg diet to 13.4 mm on Artemia , with no significant differences between diets. The mean wet weights were highest in larvae fed Artemia (77.8 mg). Results show the feasibility of weaning (gradually) even younger milk-fish larvae in hatcheries, using artificial diets.
    • Article

      White spot syndrome virus (WSSV) risk factors associated with shrimp farming practices in polyculture and monoculture farms in the Philippines 

      EA Tendencia, RH Bosma & JAJ Verreth - Aquaculture, 2011 - Elsevier
      White spot sydrome virus (WSSV) is one of the most important viral disease of shrimp. Several studies to control the disease have been done. Tank experiments identified WSSV risk factors related to the physico chemical properties of the water. A few studies reported pond level WSSV risk factors. This study identifies the risk factors associated with essentially two different farming systems: polyculture and semi-intensive monoculture of Penaeus monodon. Data were gathered from a total of 174 shrimp farmers in eight provinces of the Philippines using a structured questionnaire. Forty-seven variables related to pond history and site description, period of culture, pond preparation techniques, water management, culture methods, feed and other inputs, and biosecurity measures were investigated. In the analysis for combined monoculture and polyculture farms, feeding live molluscs was identified as important WSSV risk factors. In addition to feeding live molluscs, sharing of water source with other farms, having the same receiving and water source, larger pond size, and higher stocking density were identified as important WSSV risk factors in monoculture farms. Climate, i.e. stocking during the cold months and sludge removal and its deposition on the dikes were identified as WSSV risk factors in polyculture farms. Protective factors, listed in decreasing significance, were feeding with planktons and high mangrove to pond area ratio, both observed in the dataset with both monoculture and polyculture farms, while only the latter was observed in the dataset for monoculture farms only. No protective factor was observed in the dataset for polyculture farms.

      This study confirmed the negative effect of sharing water source with other farms and identified several new factors influencing WSSV infection such as feeding live molluscs increases the risk, while feeding with planktons and high mangrove to pond area ratio reduce the risk.
    • Article

      Why are Halophytophthora species well adapted to mangrove habitats? 

      EM Leaño, EBG Jones & LLP Vrijmoed - Fungal Diversity, 2000 - Springer Verlag
      Halophytophthora species are commonly isolated from fallen mangrove leaves from early to late stages of decay. In this study we show that these organisms are well adpted to mangrove habitats as they have a wide tolerance to varying levels of pH, salinity and temperature. They also produce, abundant zoospores, and are chemotactically attracted to decaying mangrove leaves, and can readily attach to suitable substrata. In general, the four tested isolates (H. vesicula, H. avicennae, H. kandeliae and H. bahamensis) grew at pH 6-9, with maximum growth recorded at neutral pH. Vegetative growth and sporulation were observed over a wide range of salinities (from freshwater to marine) and temperatures, although optimum requirements varied from species to species. Zoospores of Halophytophthora spp. were chemotactically attracted to mangrove leaf-extracts and some other compounds that are common to the surrounding environment. The zoospores attached and germinated on both artificial (glass coverslips and polycarbonate membranes) and natural (mangrove leaves) substrata. Scanning electron micrographs show that newly attached zoospores, cysts, and germinating cystospores of H. vesicula produced fibrillar adhesive mucilage for attachement as was evident by debris sticking to their tips. More adhesive mucilage was produced by encysted and germinating cystospores on natural as compared to artificial substrata. Cystospores and germlings of H. vesicula and H. avicennae were also found to attach firmly to a perspex disc even after being subjected to a high shear stress of 3.19 Newton per square meter (Nm-2). Enzyme treatment and staining of attached cystospores indicate that the adhesive produced is composed of acidic polysaccharide with α-1, 4 linkages, and with either sulphate or phosphate functional groups. Once the cystospores were attached to the substratum, they could not be readily dislodged, and successful germination and colonization followed.
    • Article

      Winter distribution of phytoplankton and zooplankton around some sandbanks of the Belgian coastal zone 

      A M'harzi, M Tackx, MH Daro, I Kesaulia, R Caturao & N Podoor - Journal of Plankton Research, 1998 - Oxford University Press
      The distribution of phytoplankton and zooplankton around three sandbanks (Gootebank, Westhinder and Buitenratel sandbank) off the Belgian Coast was investigated in February 1994. The abundance of phytoplankton taxa was significantly different between the sandbanks. Community analysis using TWINSPAN resulted in a clear separation of clusters corresponding to the different sandbanks. The zooplankton community analysis, on the contrary, showed a rather indistinctive division of the sandbank stations. This was due to the omnipresence of three dominant copepod species (Temora longicornis, Pseudocalanus elongatus and Centropages hamatus). When these species were excluded from the analysis, a clearer distinction between the different sandbanks was found. The observed differences in phyto- and zooplankton species distribution could be explained by the position of the sandbanks. Westhinder is positioned further from the coast than Buitenratel, while Gootebank has an intermediate position. Buitenratel and Gootebank harbour typical coastal plankton communities, while the plankton community over Westhinder is clearly influenced by the Atlantic current penetrating the southern North Sea from the English channel. More phyto-benthic species were found at Buitenratel than at Gootebank, probably because of its limited depth. Thus, the Belgian coastal zone, which is considered as one box in most spatial descriptions of the North Sea plankton, in fact harbours heterogeneous plankton communities at the end of winter.
    • Article

      Withdrawal of exogenous 17-alpha methyltestosterone causes reversal of sex-inversed male grouper Epinephelus suillus (Valenciennes) 

      JD Tan-Fermin - The Philippine Scientist, 1992 - San Carlos Publications
      The protogynous hermaphrodite groupers Epinephelus suillus were given bi-weekly injections of 17 alpha-methyltestosterone (MT) intramuscularly for three to six months. Spermatogenesis occurred after three months of MT treatment while spermiation was observed after five to six months of MT treatment in larger fish. Neither cannulated tissue nor milt was obtained when the remaining fish were sampled four months after withdrawal of exogenous MT. However, vitellogenic eggs (size range = 0.34 to 0.56 mm) were cannulated eight months after termination of MT treatment. Presence of eggs in fish which previously had expressible or cannulated milt indicates that the sex-inversed male E. suillus reverted back to the female condition upon withdrawal of exogenous MT. This information is useful in the line production of functional males which is the limiting factor in induced breeding of groupers.
    • Article

      Women and the question of sustainable development in a Philippine fishing village 

      SV Siar & LM Cañeba - International Journal of Sustainable Development and World Ecology, 1998 - Taylor & Francis
      This paper presents a case study of time use and contribution to the household income of men, women, and children in 12 households in a fishing village in Panay Island, central Philippines. The study highlights the differential impact of poverty on men and women and provides a glimpse of the intrahousehold dynamics within poor fishing households. Findings in previous studies in both industrialized and developing countries that women work longer hours than men were corroborated. Women contribute at least 22% to the household cash income and 40% of the value of unpaid labour. Their contribution to the household cash income becomes larger than that of men's when the value of livestock is computed. Women's daily participation in productive activities, such as fish vending and shucking oyster and mussel, unwittingly puts them in a position of being environmental recorders and verifiers of the state of fishery resources. Because they are burdened with the responsibility of making ends meet, they are also confronted with the challenge of realizing the dream of sending their children to university to enable them to escape poverty. This alone makes women one of the strongest stakeholders in the sustainable development of fishery resources.
    • Article

      World wide aquaculture drug and vaccine registration progress 

      RA Schnick, DJ Alderman, R Armstrong, R le Gouvello, S Ishihara, EC Lacierda, S Percival & M Roth - European Association of Fish Pathologists Bulletin, 1997 - European Association of Fish Pathologists
      Harmonisation of the most important standards and guidelines required in each country. A start has been shown to be made in developing an international effort toward aquaculture drug approvals and vaccine licensure and toward establishing harmonised guidelines and standards for facilitating registrations world-wide.
    • WSSV risk factors related to water physico-chemical properties and microflora in semi-intensive Penaeus monodon culture ponds in the Philippines 

      EA Tendencia, RH Bosma & JAJ Verreth - Aquaculture, 2010 - Elsevier
      Whitespot syndrome virus, WSSV, is the most important among the shrimp diseases. One of the suggested WSSV risk factors is the occurrence of stress since stressors could compromise the shrimp defence system thus increasing the risk of WSSV infection. Stressors are usually related to the physico-chemical properties of both water and pond bottom. This paper investigates the effect of some biotic and abiotic components of the pond ecosystem on WSSV infection and outbreak. Water physico-chemical properties and microflora of 91 production cycles of 8 semi-intensive shrimp farms were analyzed to determine WSSV risk factors, using factor analysis and logistic regression. Fluctuations of temperature and pH are important risk factors that will result to an infection but not necessarily to an outbreak. Exposure to high salinity and high temperature are important factors for an infection to result to an outbreak. The risk of an infection is reduced when the water temperature is high, salinity fluctuations are small, and percentage of yellow Vibrio colonies is greater than the green ones. Further studies are needed to clarify the effects of water depth, water transparency, and various bacterial counts; these factors could be individual or interactive.
    • Article

      Year-round sexual maturation of bighead carp Aristichthys nobilis (Richardson) reared in floating cages in Laguna de Bay (Philippines). 

      AC Fermin - Journal of Applied Ichthyology, 1990 - Blackwell Publishing
      Sexual maturation in bighead carp Aristichthys nobilis reared without supplemental feeding in floating cages in Laguna de Bay was observed year-round. Percent maturation ranged from 3 to 94% in females and 0 to 82% in males from July 1985 to July 1986. High maturation rates in both sexes occurring in March 1986 were positively correlated with high inorganic turbidity in the lake. Low natural food productivity (phyto- and zooplankton) during high turbidity did not negatively affect fish growth. Fish may have depended partly on suspended particles as additional food sources when production of more suitable food (zooplankton) was low. Increased production of natural food as a result of water clearing by seawater intrusion during May to September did not enhance growth and maturation of the fish. There was a low negative correlation between chlorinity and percent maturation of both sexes.
    • Article

      Year-round spawning and seed production of the rabbitfish, Siganus guttatus 

      S Hara, MN Duray, MM Parazo & Y Taki - Aquaculture, 1986 - Elsevier
      A series of experiments on the spawning and larval rearing of Siganus guttatus was conducted during a 14-month period in 1984–1985. Spawning occurred every month throughout the year, without hormonal treatment, between the first quarter and the full moon. Fertilization rates and hatching rates were high, with means of 84.2% (n=38) and 89.6% (n=34), respectively. Females that had been fed diets rich in cod liver oil or in a cod liver oil/soybean oil/soybean lecithin mixture spawned repeatedly for at least 4 consecutive months. Larvae reared in 20, 26, and 32‰ salinities showed no significant differences in survival rates at day 21. Survival was higher for larvae fed during days 2–4 with rotifers strained through an 80-μm-mesh plankton net than for those fed unstrained rotifers. Larvae readily accepted Artemia nauplii and artificial diets when these were first introduced on day 15 and day 23, respectively. Higher larval survival was obtained in large tanks (≥5 m3) than in small tanks (500 l). Survival rates of 3.5–16.6% (x=7.5%) at day 45 were obtained in six trials of mass larval rearing and 5500–50100 (x=27 700) juveniles per female were produced at day 45, ready for stocking in grow-out farms.
    • Article

      The yellow mangrove: its ethnobotany, history of maritime collection, and needed rehabilitation in the central and southern Philippines 

      JH Primavera & L de la Peña - Philippine Quarterly of Culture & Society, 2000 - University of San Carlos Publications
      Most mangrove reforestation program in the Philippines and elsewhere in Asia focus on the genus Rhizophora, hence there is a need to identify and develop planting and harvesting techniques for other mangrove species, especially those in high demand by coastal communities. The yellow mangrove Ceriops tagal is one such species. Its many uses as firewood, poles for fish-corrals and traps, house construction, medicine (wound cleansing, treatment of hemmorhages), in the production of dyes (for dyeing fish nets, ropes, cloth and rice as a festive food) and as a mordant from bark are widely reported from the Philippines and all over Southeast and South Asia. An extensive sea-based industry for collecting C. tagal bark or tungog existed in the Philippines in the 1930s-1950s. It is heretofore described as undocumented industry including the boats used, collecting sites, markets, financing system and profit-sharing. Because C. tagal lacks reserve meristems, cutting of the trunk during bark gathering causes tree mortality. This explains the wholesale disappearance of the species from areas where it has been harvested throughout the Philippines, Southeast and South Asia, and East Africa. Research is needed to refine planting techniques and develop bark harvesting methods that do not kill the tree. Until nondestructive procedures for bark collection are finally perfected, C. tagal stands can be planted and harvested on a rotation basis.
    • Article

      Yield of Penaeus monodon Fabricius in brackishwater ponds given different fertilizer combinations 

      PF Subosa & MN Bautista - Aquaculture, 1991 - Elsevier
      Yields of Penaeus monodon Fabricius in brackishwater earthen ponds were determined using different fertilizer combinations in two sets of experiments. Results indicated that the use of fertilizers was vitally needed to sustain growth of shrimps at a stocking density of 5000 individuals/ha. Application of urea (45-0-0) and diammonium phosphate (18-46-0) fertilizers at nitrogen to phosphorus fertilizer rates (N:P2O5) of 15:15 and 30:15 kg/ha, together with 1 t/ha of chicken manure, was inexpensive and resulted in better yields. In another experiment, increase in the amount of nitrogen and phosphorus fertilizers did not significantly improve prawn yields, but did increase the cost of production. Different salinity levels affected survival in both experiments.
    • Article

      Yolk and oil globule utilization and developmental morphology of the digestive tract epithelium in larval rabbitfish, Siganus guttatus (Bloch) 

      EM Avila & JV Juario - Aquaculture, 1987 - Elsevier
      The purpose of this study was to find out how yolk and oil globule absorption in Siganus guttatus proceed as the digestive tract develops, in order to determine the probable causes of early larval mortality. Yolk and oil globule absorption in the rabbitfish were compared with the same processes in the more sturdy seaperch larvae during the first 10 days of larval life under identical rearing conditions in 32‰ sea water at 27°–30°C. The rapid decline of yolk in both species coincided with the rapid development of the digestive system within 24 h from hatching, indicating that most of the yolk was used for organogenesis. Whereas yolk was depleted in both fish in 3 days, the oil globule persisted in the rabbitfish only for 4 days and in the seaperch for 7 days. Oil globule depletion in the rabbitfish coincided with a negative mean length increment, implying an energy deficit even when the larvae had already started to feed. Ultrastructural observations of the gut epithelia of the rabbitfish revealed pinocytosis in the hindgut cells immediately after ingestion of rotifers, well in advance of complete yolk and oil globule absorption. Therefore, starvation due to exhaustion of the endogenous energy reserves in addition to the physical inability to feed were ruled out as major causes of larval mortality in rabbitfish.
    • Article

      Yolk resorption, onset of feeding and survival potential of larvae of three tropical marine fish species reared in the hatchery 

      T Bagarinao - Marine Biology, 1986 - Springer Verlag
      This paper provides basic early life-history information on milkfish (Chanos chanos), seabass (Lates calcarifer) and rabbitfish (Siganus guttatus) which may explain in part the observed differences in their survival performance in the hatchery. Egg size, larval size, amount of yolk and oil reserves and mouth size are all greater in milkfish than in seabass, and greater in the latter than in rabbitfish. During the first 24 h after hatching, rabbitfish larvae grow much faster than milkfish and seabass larvae at similar ambient temperatures (range 26°–30°C, mean about 28°C). The eyes become fully pigmented and the mouths open earlier in seabass and rabbitfish (32–36 h from hatching) than in milkfish (54 h). Seabass larvae learn to feed the earliest. Yolk is completely resorbed at 120 h from hatching in milkfish, and yolk plus oil at 120 h in seabass and 72 h in rabbitfish at 26° to 30°C. Milkfish and seabass larvae have more time than rabbitfish to initiate external feeding before the endogenous reserves are completely resorbed. Delayed feeding experiments showed that 50% of unfed milkfish larvae die at 78 h and all die at 150 h from hatching. Milkfish larvae fed within 54 to 78 h after hatching had improved survival times: 50% mortality occurred at 96 to 120 h, and 10 to 13% survived beyond 150 h. Unfed seabass larvae all died at 144 h, while 6 to 13% of those fed within 32 to 56 h after hatching survived beyond 144 h and well into the subsequent weeks. Unfed rabbitfish larvae all died at 88 h, while 7 to 12% of those fed within 32 to 56 h after hatching survived beyond 88 h. A delay in initial feeding of more than 24 h after eye pigmentation and opening of the mouth may be fatal for all three species.