Now showing items 1045-1064 of 1075

    • Article

      Vaccination of European sea bass fry through bioencapsulation of Artemia nauplii 

      M Chair, RSJ Gapasin, M Dehasque & P Sorgeloos - Aquaculture International, 1994 - European Aquaculture Society
      European sea bass (Dicentrarchus labrax) fry vaccinated orally via bioencapsulation in Artemia nauplii or by bath method exhibited better performance than control fish in terms of growth, food conversion and resistance to stress. The comparable survival between vaccinated and non-vaccinated animals suggests that vaccination methods are not stressful. The present study shows that oral vaccination can be used to enhance growth in fish fry.
    • Article

      Valine requirement of postlarval tiger shrimp, Penaeus monodon Fabricius 

      OM Millamena, MN Bautista-Teruel & A Kanazawa - Aquaculture Nutrition, 1996 - Wiley-Blackwell
      The valine requirement of juvenile tiger shrimp, Penaeus monodon Fabricius, was determined. Shrimp postlarvae, PL20, with a mean weight of 14 mg, were randomly distributed in 36 oval 40-L capacity fibreglass tanks at 10 shrimp per tank in a flow-through seawater system and reared for 8 weeks. Postlarvae were fed amino acid test diets containing 400 g kg−1 protein with casein and gelatine as intact sources of protein. Crystalline L-amino acids were supplemented to simulate the amino acid profile of the shrimp muscle except valine. Valine was added in graded levels to obtain 7, 10, 13, 16, 19 and 22 g kg−1 of the diet or 18, 25, 33, 40, 48 and 55 g kg−1 of dietary protein. At termination of the feeding experiment, growth and survival were determined and nutritional deficiency signs noted. The relationship between weight gain and dietary valine level was analysed by the broken-line regression method to derive the valine requirement. The dietary valine requirement of Penaeus monodon postlarvae was found to be 13.5 g kg−1 of the diet or 34 g kg−1 of dietary protein. This value was lower than the level found in the shrimp tissue.
    • Article

      Variation in the biochemical composition of Penaeus monodon tissues during the reproductive cycle. 

      V Dy-Peñaflorida & OM Millamena - The Israeli Journal of Aquaculture-Bamidgeh, 1990 - Bamidgeh
      The gonadosomatic index (GSI) and the hepatosomatic index (HSI) were determined for wild-caught, eyestalk ablated Penaeus monodon at 5 reproductive stages (I to V). Tissues of the muscle, ovary and hepatopancreas in each stage were analyzed for crude protein and amino acid composition.

      Results showed that the GSI increased from stage I (immature) to IV (fully mature) but declined at stage V (spent) while the HSI did not change significantly (P less than or equal to 0.05). Muscle protein content did not vary markedly from stage I to V except for a slight lowering at stage III (late maturing). Ovarian protein increased from stage I to IV and decreased at stage V while from stage II, the reverse was true for hepatopancreas.

      Generally, few significant differences in amino acid content were found. Glutamic acid content significantly differed among stages in all three tissues. In addition, phenylalanine in the muscle, histidine and lysine in the ovary and arginine and luecine in the hepatopancreas differed among stages. The muscle had slightly higher arginine and gluatmic acid contents than the ovary and hepatopancreas but was lower in threonine and valine. The ovary had the lowest glycine content.

      Results showed similar amino acid levels among tissues and maturation stages, suggesting that amino acids are fixed and not affected by much variation.
    • Article

      Variation in the vertebral number of the milkfish Chanos chanos, collected from various localities 

      T Senta & S Kumagai - Bulletin- Faculty of Fisheries Nagasaki University, 1977 - The Faculty of Fisheries, Nagasaki University
      A total of 2497 milkfish fry were collected in 1976 from nine localities in six countries, viz. India, Thailand, Indonesia, Philippines, Taiwan and Tahiti. Vertebra counts ranged from 40 to 45. The general trend of geographical gradient in vertebral counts in the milkfish was observed to be lower in the west (or otherwise, along continents) and higher in the east (or around oceanic islands). Extremes in the means of vertebral counts by localities were seen in the samples from India with 43.08 and from Tahiti with 43.82. It was suggested that there may be at least four subpopulations among the milkfish throughout the tropical Indo-Pacific waters.
    • Article

      Variation of otolith strontium concentration in elongate surgeonfish, Acanthurus mata 

      S Seike, JD Toledo, T Umino & H Nakagawa - Ite Letters on Batteries New Technologies and Medicine, 2005 - Ite-iba Inc.
      The Elongate surgeonfish Acanthurus mata caught from the sea and feeding in the milkfish’s net cages separated from wild fish were measured for their otolith strontium (Sr) concentration using an wave-length dispersive electron probe micro analyzer. The analysis showed three types of Sr distributions in the otolith of wild fish, but the type from artificially fed fish caught in cages was unchanged. The Sr concentration in the otolith could be influence by the water chemistry and/or food composition, and other factors. In conclusion, if you try understand the Elongate surgeonfish life-history based on it’s Sr concentration variation, one should take great care.
    • Article

      Vertical distribution of euthecosomatous pteropods in the upper 100m of the Hilutangan Channel, Cebu, The Philippines 

      NB Solis & H Westernhagen - Marine Biology, 1978 - Springer-Verlag
      The vertical distribution of euthecosomatous pteropods in the upper 100 m of the Hilutangan Channel, Cebu, The Philippines was studied, based on 126 samples, comprising 47, 282 individuals. Thirty-min horizontal plankton tows were performed at depths of 1, 20, 50, 70 and 100 m in January and February 1972. Thirteen species -including 3 subspecies - of juvenile and adult euthecosomes were identified. In decreasing order of abundance the species are: Creseis acicula (20.4%), Limacina trochiformis (19.9%), Creseis virgula constricta (14.6%), L. inflata (10.5%), Clio pyramidata (9.9%), Creseis virgula conica (8.9%), L. bulimoides (7.3%), Diacria quadridentata (5.3%), Cavolinia longirostris (1.9%), Creseis virgula virgula (1.0%), Hyalocylix striata (0.1%), Cuvierina columella (0.08%), Cavolinia uncinata (0.002%). In 3 species, a large percentage were juveniles; for 1 species, Clio pyramidata , only juveniles were caught. The Vertical species distribution was similar to the distribution of the respective species in Caribbean and Bermuda waters. Temperature, salinity and dissolved oxygen influence vertical distribution little, if at all.
    • Article

      Vertical diurnal migration of Daphnia cucculata and Eudiaptomus graciloides in eutrophic Frederiksborg Castle Lake, Denmark 

      MH Carlos - Kalikasan, The Journal of Philippine Biology, 1982 - University of the Philippines at Los Baños
      In euthrophic Frederiksborg Castle Lake, Berg & Nygaard were the first to study vertical migration. They obtained water samples at various time intervals over several days and concluded that the bulk of the population of the zooplankton they were studying shifted from one depth to another. D. cucculata and E. graciloides are the two most dominant zooplankters in Frederiksborg Castle Lake. The vertical migration of these species was studied, and the observations are reported in this paper.
    • Article

      Vertical rope cultivation of Gracilaria (Rhodophyta) using vegetative fragments 

      AQ Hurtado-Ponce - Botanica Marina, 1990 - Walter de Gruyter
      Preliminary field culture of Gracilaria using vegetative fragments inserted between braids of ropes suspended vertically inside a floating cage was undertaken to assess the daily growth rate and monthly yield as influenced by three different spacing intervals.

      Daily growth rate of cuttings at 10 cm intervals ranged from 0.6 to 7.2% with yields of 11 to 415 g m-1 line1, those at 15 cm from 1.4 to 9.1% with yields of 18 to 502 g m-1 line-1, and at 20 cm from 1.7 to 10.5% and with yields of 20 to 379 g m-1 line-1. Both growth and yield were minimum in December at all spacing intervals but maximum in April at 10 and 15 cm and in February at 20 cm.

      Results of the analysis of variance (ANOVA) showed a non-significant interaction between spacing interval and culture month on daily yield of Gracilaria. This indicates that the effect of spacing interval on the daily growth rate and monthly yield was not significantly influenced by the culture month; likewise the effect of culture month did not differ significantly with the intervals used. The main effects, however, of spacing interval and culture month to daily growth rate were significant. Yield was significantly affected by the culture month but not by spacing interval.
    • Article

      Viability of a bottom-set tray ocean nursery system for Holothuria scabra Jaeger 1833 

      JRC Gorospe, JP Altamirano & MA Juinio-Meñez - Aquaculture Research, 2017 - Wiley
      Scaling up the hatchery production of juvenile sandfish Holothuria scabra is constrained by limited hatchery space and the associated high operational costs. To shorten the hatchery rearing phase, ocean nursery systems like floating hapa nets have been used with good prospects but with limitations during rough sea conditions. In this study, the potential of bottom‐set trays (0.14 m2) as an alternative ocean nursery system for early sandfish juveniles (0.5 ± 0.1 cm) was evaluated. The effects of stocking density and presence of artificial substrates (AS) on the growth and survival were determined in a 60‐day field experiment. Average length and growth rates at lower stocking density treatment (100 individuals tray-1) were significantly higher (1.45 ± 0.22 cm; 0.03 ± 0.01 cm day-1) than at higher stocking density treatments (400 and 500 individuals tray-1) 0.95 ± 0.06 cm; 0.03 ± 0.004 cm day-1) with or without AS (p < .05) respectively. The coefficient of variation in length (CV) at high stocking densities were significantly higher than at low densities (p < .05) and growth rate was strongly negatively correlated with density. Survival was significantly higher (55% ± 9%) in trays with AS across all stocking density treatments than in trays without AS (34% ± 2%). Results suggest that AS may have reduced intra‐ and interspecific interactions, resulting to significantly lower growth variations and higher survival. The bottom‐set tray with AS can be a practical alternative ocean nursery unit for rearing early sandfish juveniles particularly when the sea surface condition is rough. With improved design and density management, survival and growth may be further enhanced.
    • Article

      Viability of frozen algae used as food for larval penaeids 

      E Jereos-Aujero & OM Millamena - Fisheries Research Journal of the Philippines, 1981 - Fisheries Research Society of the Philippines
      Freezing with added chemicals as flocculants and protectants as means of preserving stock cultures was tried with four species commonly used as larval food. The species were Chaetoceros calcitrans, Skeletonema costatum, Tetraselmis chuii , and Isochrysis galbana.

      Except in I. galbana , this method successfully preserved the viability of the algae tested. C. calcitrans , was viable up to eighteen months storage; T. chuii , four months; and S. costatum , two months.

      Cryophylaxis did not seem to greatly increase the viability of frozen cells except with T. chuii ; however, with the diatoms, viability was preserved regardless of the harvesting flocculant used and whether or nor protectants were added.
    • Article

      Vibrio sp. isolated from milkfish (Chanos chanos) with opaque eyes 

      K Muroga, GD Lio-Po, C Pitogo & R Imada - Fish Pathology, 1984 - Japanese Society of Fish Pathology
      Several milkfish (Chanos chanos) juveniles polycultured with the Indian prawn (Penaeus indicus) in earthen ponds at the Leganes Station of the Aquaculture Department, SEAFDEC, Philippines, manifested eye abnormalities. Signs observed varied from unilateral and bilateral opaque eye coverings/eye balls, exophthalmia and hemorrhagic eyes. A vibrio was predominantly isolated from the opaque eye coverings and eye balls, and it was proved pathogenic to milkfish, Japanese eel (Anguilla japonica) and mouse by injection experiments. The opaqueness of eye coverings of milkfish was likewise reproduced by a combination of injury and contact with the pathogen.

      The bacterium, though seemingly closely related to Vibrio parahaemolyticus or V. alginolyticus, was not identified to any known Vibrio species.
    • Article

      Virulence and production of extracellular proteins (ECP) of Aeromonas hydrophila associated with the epizootic ulcerative syndrome (EUS) of freshwater fish. 

      EM Leaño, GD Lio-Po & LA Dureza - UPV Journal of Natural Sciences, 1996 - University of the Philippines in the Visayas
      Sixteen isolates of Aeromonas hydrophila isolated from normal, apparently normal and epizootic-ulcerative syndrome (EUS)-affected fish were screened for virulence and production of extracellular proteins (ECP). Results showed that all isolates were virulent to catfish (Clarias batrachus) juveniles inducing dermonecrotic lesions after intramuscular injection. Lesions were characterized by necrosis of the underlying musculature that leads to erosion and sloughing-off of the locally affected tissues. Only seven of the 16 ECP preparations, however, induced similar lesions on test catfish. No clear correlation between virulence and ECP production of EUS-associated A. hydrophila was established.
    • Article

      The visual feeding threshold and action spectrum of northern anchovy (Engraulis mordax) larvae 

      T Bagarinao & JR Hunter - California Cooperative Oceanic Fisheries Investigations Reports, 1983 - California Cooperative Oceanic Fisheries Investigations
      The visual feeding threshold and action spectrum of 10-15-mm northern anchovy larvae were determined, using as criterion the incidence of two or more rotifers in the guts of 50% of larvae tested under different spectral irradiances. The threshold sensitivity ot broadbank blue-green light is at 0.15 µWcm-2=0.61 lux. The action spectrum shows a mixumum in the green wavelengths around 530 nm: the weighted threshold irradiances at various wavelength bands converge at a mean value of 0.14 µWcm-2anch eff.

      The visual abilities of the anchovy allow them to feed at a depth of 74 m at noon on clear days, and at the surface during twilight and bright nights, and appear to be well adapted to the anchovy's habitat in turbid, greenish coastal waters. Comparisons with younger anchovy larvae show that changes in visual function accompany changes in eye and retinal morphology, specifically the recruitment of rods. Moreover, 10-15-mm anchovy larvae can feed to a limited extent (10%) in the dark when food densities are high (20-40 rotifers/ml). In March, which is the peak spawning season of the anchovy in southern California and Baja California, the 10-15-mm larvae have 13 hours each day to feed.
    • 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.