Now showing items 489-508 of 1070

    • Article

      Haliphthoros spp. from spawned eggs of captive mud crab, Scylla serrata, broodstocks 

      EM Leaño - Fungal Diversity, 2002 - Springer Verlag
      Monitoring of the fungal flora of spawned eggs of captive mud crab, Scylla serrata, was conducted in several hatchery runs at the Aquaculture Department of Southeast Asian Fisheries Development Center in Iloilo, Philippines. Quantification of the egg mycoflora revealed the dominance of oomycetes, particularly Haliphthoros spp. among spawners which aborted their eggs prior to hatching. Two species of Haliphthoros (H. philippinensis and H. milfordensis) were identified from the 24 isolates collected. Haliphthoros milfordensis was the dominant species. Physiological studies on vegetative growth and sporulation of the two species show that H. philippinensis have wider optimal range for salinity and temperature requirements than H. milfordensis, especially in sporulation. The pathogenicity study showed that only H. milfordensis was pathogenic to spawned eggs of S. serrata, while H. philippinensis was not. Infection of S. serrata eggs by H. milfordensis was observed starting at two days after inoculation of zoospores with 2-5% infection rate, reaching up to 10% at five days post-inoculation.
    • Article

      Harvesting Gracilariopsis heteroclada (Gracilariales, Rhodophyta) in Iloilo, Philippines 

      AQ Hurtado-Ponce - Philippine Journal of Science, 1993 - Science and Technology Information Institute
      Gracilariopsis heteroclada thalli were planted in a 1 m2 ditch along a drainage canal at Leganes, Iloilo, Philippines. Monthly growth rate and production were calculated to determine the effect of harvesting on the regeneration capacity of the plant. After 30-day growth period, all plants were harvested at 25%, 50%, 75%, and 100% of the total available biomass. Though highest growth rate was observed at 100% (8.7%), it took three months for the plants to regenerate and obtain a considerable biomass. Positive growths were obtained when plants were harvested at 75% (5.6%) during the entire growth period. Negative growth rates observed both at 25 and 50% harvests.
    • Article

      Harvesting techniques for Nile tilapia fingerlings 

      NS Tabbu, RB Lacierda & RV Eguia - Fisheries Research Journal of the Philippines, 1986 - Fisheries Research Society of the Philippines
      The experiment was conducted in nine-320m2 - freshwater ponds to evaluate various techniques of harvesting tilapia fry. Three treatments with three replicates each were used: harvesting by seining the fry (Treatment I), daily harvesting of fry in ponds using fine-mesh scoop net (Treatment II) and harvesting of fry from hapa net cages installed in ponds (Treatment III). All broodstock ponds were prepared, maintained uniformly and sustained through fertilization at recommended dose.

      Results of the two trials/experiments indicated that the recovery of fry in hapa net installed in ponds is far superior than the other two techniques but mortality in all treatments is not significant.

      Hapa cages are used here as a tool for easy management as well as mechanical aid to prevent predation of fry and cannibalism inherent if fish is directly stocked in ponds. Hapa also served as substrate for natural food and additional grazing areas for young tilapia fry which resulted in high recovery.
    • Article

      Hatchery production of Oreochromis niloticus L. at different sex ratios and stocking densities 

      AM Bautista, MH Carlos & AI San Antonio - Aquaculture, 1988 - Elsevier
      The influence of various sex ratios and stocking densities on hatchery production of Nile tilapia, Oreochromis niloticus L., was studied in land-based (concrete tanks) and lake-based (hapa nets) systems. In both hatchery systems, egg and fry production was maximum at a sex ratio of 4:1 females to males and a density of 4 females per m2.

      Seed production varied significantly among treatments at different periods of the year. In concrete tanks, significantly high seed production of 12.98 and 11.77 eggs and fry per spawner per day was obtained in March and August, respectively. In hapa nets, irrespective of sex ratios, 10.18 seeds per spawner were collected daily in March.

      In relation to the broodstock density in concrete tanks, significantly bigger daily harvests of 13.41 and 13.00 eggs and fry per spawner were produced in late February and March, respectively. In hapa nets, daily harvests of 8.95 and 7.74 eggs and fry per spawner were the highest seed production levels which occurred in April and March, respectively.

      Seed production was significantly higher in concrete tanks than in hapa nets while insignificant differences (P>0.05) were found among sex ratio and broodstock density treatments.
    • Article

      Hatchery rearing of sea bass Lates calcarifer Bloch 

      MM Parazo, DM Reyes Jr. & EM Avila - The Philippine Scientist, 1991 - Science and Technology Information Institute
      A hatchery rearing scheme for sea bass (Lates calcarifer Bloch) is described. Survival rate from hatching (d0) to harvest (d30) was 34%. Feeding sea bass fry with Chlorella-fed or Selco-enriched instar II Artemia from d19 to d23 resulted in similar survival rates (74%), total length (8.2 and 8.9 mm) and weight (8.9 and 12.1 mg) at d30. Although sea bass fry fed 2.5, 5 or 10 Artemia/ml/day from d14 to d20 exhibited similar survival rates (73-93%), fish were significantly larger as feed density increased (7.1, 8.2, 9.8 mm total length and 2.4, 4.3, 9.7 mg wet weight, respectively). The significance of this study lies in providing technical information on artificial production of sea bass fry.
    • Article

      Hatchery-produced milkfish (Chanos chanos) fry should be fed docosahexaenoic acid-enriched live food: A case of the difficulty in the transfer of improved aquaculture technology in the Philippines 

      HY Ogata, DR Chavez, ES Garibay, H Furuita & A Suloma - Japan Agricultural Research Quarterly, 2006 - Ministry of Tropical Agricultural Research Centre
      Levels of highly-unsaturated fatty acids, the most important nutritional factors in fry production of marine fish, were compared between hatchery-produced and wild-caught milkfish Chanos chanos fry. The most striking difference found between the fry was in docosahexaenoic acid (DHA: 22:6n-3) levels: DHA levels in hatchery-produced fry were only 37% and 18% of those in wild-caught fry in the polar lipids and neutral lipids, respectively. However, high DHA levels were detected in ovary and spawned eggs from hatchery-reared broodstock. Investigation on the time course change in DHA levels of hatchery-produced fry revealed that the DHA levels of polar lipids drastically declined from 25% at day 0 posthatching to 5% at day 14 posthatching. Nannochloropsis sp. and rotifers Brachionus sp., which were used as live food from day 2 to day 14, did not contain DHA with relatively high eicosapentaenoic acid (EPA: 20:5n-3) levels. DHA level was restored to 13% in 45-day old fry by feeding of formulated diets with a substantial amount of DHA from day 15. Thus, the lack of DHA in the live food appears to lead to the low DHA level in hatchery-produced fry. On the other hand, the cost of DHA enrichment for one milkfish fry was estimated to be 2.6 Philippines centavos, which is equivalent to about 10% of the market price of milkfish fry. The increase of the production cost might not be accepted in domestic hatcheries under competitive marketing with imported fry. Financial and marketing support by the government will be one of the measures to encourage the stable production of domestic milkfish fry with high quality in the Philippines. It is also necessary to conduct institutional campaigns to inform local fry producers and milkfish farmers of the importance of DHA-enrichment.
    • Article

      HCG and LHRH-A induced spawning in bighead carp Aristichthys nobilis Rich. reared in floating cages in Laguna de Bay 

      AC Fermin & DM Reyes Jr. - The Philippine Scientist, 1989 - San Carlos Publications, University of San Carlos
      Hormone-induction of spawning in bighead carp Aristichthys nobilis Rich. by single or double intraperitoneal injection with varying combined dosages of HCG and LHRH-A was conducted. Fish were spawned successfully following a single or double injection with 1800 to 2000 IU HCG in combination with 10, 15 or 20 µg HRLR-A per kg body weight. Fish injected with lower dosages of HGC at 1200 or 1500 IU/kg body weight plus 20 µg/kg LHRH-A did not differ significantly (P>0.05). Fish given a single injection ovulated after 12.0 ± 0.1 hours. No significant difference was found in the total number of eggs spawned per fish among the injection protocols (P>0.05). However, lower fertilization and hatching rates of eggs were observed in fish that spawned spontaneously in the tank as compared to those fish whose eggs were stripped and dry-fertilized (P<0.05).
    • Article

      Histological observations on the rearing of milkfish, Chanos chanos, fry using different diets 

      H Segner & JV Juario - Journal of Applied Ichthyology, 1986 - Blackwell Publishing
      Six different diets, commonly used in the Philippines for rearing milkfish, Chanos chanos, try, were tested by means of growth, survival and histology. These diets included:

      a) live food (Artemia nauplii); b) two different dry feeds; c) natural feed supplements (rice bran, egg yolk); d) a mixture of live and dry feeds. The mixed diet was found to give the best results, closely followed by live food. The dietary value of one of both artificial feeds improved with increasing age of the fish, whereas the other was clearly inadequate. The same was true for the natural compounds. Results obtained from statistical and histological analyses were congruent; the latter provided additional insights not obtained with statistic data alone.
    • Article

      A histological study of the hypophysial-gonadal system during sexual maturation and spawning in the milkfish, Chanos chanos (Forskal) 

      JD Tan - Journal of Fish Biology, 1985 - Wiley-Blackwell
      The pituitary gland of the milkfish, Chanos chanos, was studied at different stages of sexual maturation and spawning. Consecutive median sagittal sections were treated with a range of stains to demonstrate the different cell types and regions. The milkfish pituitary consists of a neural component, the neurohypophysis, and an epithelial component, the adenohypophysis, which in turn consists of three regions: the rostral pars distalis (RPD), proximal pars distalis (PPD), and pars intermedia (PI). However, unlike most teleosts, the pituitary gland of the milkfish is encased in a bony chamber, has dorsal and ventral lobes and extends anteriorly from its point of origin at the base of the brain. PAS (+) basophils are found in all regions of the adenohypophysis, but mostly in the proximal pars distalis. These cells undergo hypertrophy and hyperplasia during sexual maturation, shrinkage and degranulation during spawning.
    • Article

      Histopathological response of milkfish Chanos chanos Forsskal fingerlings to potassium permanganate 

      ER Cruz & CT Tamse - Fish Pathology, 1986 - Japanese Society of Fish Pathology
      Static 96 h bioassays were conducted on milkfish fingerlings at concentrations ranging from 1.00 to 1.80 mg/l KMnO4. Histopathological analyses of gills, liver, and kidney tissues revealed significant changes even in non-lethal concentrations tested. Damage became severe with increasing concentration and longer exposure to the chemical. Partial to complete recovery was observed in gills, liver, and kidney cells of fish exposed to KMnO4 for 96 h and then maintained in KMnO4-free seawater for 240 h.
    • Article

      Histopathology of microsporidian infection in white prawn, Penaeus merguiensis de Man, 1888. 

      MCL Baticados & GL Enriquez - Natural and Applied Science Bulletin, 1982 - University of the Philippines
      Different stages of the white prawn, Penaeus merguiensis de Man, were examined for microsporidian infection. The parasite was found only in adult female prawns exhibiting white instead of the normal olive-green ovaries. Non-germinal tissues were not infected. Spores found in the digestive tract, abdominal muscles, hepatopancreas, heart and gills were extracellular in location and did not have any histopathologic effect on these organs.
    • Article

      Histopathology of the chronic soft-shell syndrome in the tiger prawn Penaeus monodon 

      MCL Baticados, RM Coloso & RC Duremdez - Diseases of Aquatic Organisms, 1987 - Inter Research
      One of the disease problems that affect the production of tiger prawn Penaeus monodon Fabricius in brackish-water ponds is the chronic soft-shell syndrome, a condition in which the prawn shell is persistently soft for several weeks. To determine the extent of damage in affected prawns, the histopathology of this syndrome was studied using light microscopy, transmission and scanning electron microscopy, and histochemical determination of calcium. Light microscopic studies of the exoskeleton of soft and normal hard-shelled prawns showed several distinct layers: an outer epicuticle, a thick exocuticle and a thinner endocuticle overlying the epidermis. The cuticular laters of the soft shell oftern had a rough or wrinkled surface and were usually disrupted and separated from the epidermis while those of the hard shell were generally intact and attached to the epidermis. The exocuticle and endocuticle of the hard shell were considerably thicker than those of the soft shell. Ultrastructural observations revealed the presence of a very thin membranous later under the endocuticle. Tegumental ducts and pore canals traversed the 4 cuticular layers and were distinctly observed as pore openings on the epicuticle surface. The epicuticle had a bilaminar and non-lamellate structure. The exocuticle had more widely-spaced lamellae consisting of fibers arranged in a more compact pattern than in the endocuticle. Histochemical determination of calcium was done in exoskeleton and hepatopancreas of soft- and hard-shelled prawns. The hepatopancreas of soft-shelled prawn stained more intensely for calcium than that of the hard-shelled one. There was no great difference in calcium content of hard and soft shell, although the former stained slightly more intensely. Histopathological changes in the hepatopancreas of soft-shelled prawns were also observed.
    • Article

      Horizontal transmission of epizootic ulcerative syndrome (EUS)-associated virus in the snakehead Ophicephalus striatus under simulated natural conditions 

      GD Lio-Po, LJ Albright, GS Traxler & EM Leaño - Diseases of Aquatic Organisms, 2003 - Inter Research
      Natural transmission of the epizootic ulcerative syndrome (EUS) was conducted on naïve snakeheads Ophicephalus striatus (also known as Channa striata) kept (A) in aquifer water, (B) in lakewater, (C) cohabiting with EUS snakeheads in lakewater, and (D) cohabiting with apparently healthy snakeheads in lakewater during the 1994 to 1995 EUS season. The results showed that EUS-like lesions developed in 6 to 14 d among naïve snakeheads cohabiting with EUS snakeheads and with apparently healthy snakeheads in lakewater (Treatments C and D). Among naïve fish exposed to lakewater (Treatment B), similar lesions developed in 16 to 21 d, while naïve fish in aquifer water (Treatment A) did not develop EUS-like lesions. EUS signs began as Grade I (slight) lesions that gradually progressed to Grades III-IV (severe) 3 to 5 d from lesion onset, similar to the naturally affected EUS fish. The virus was recovered from some but not all naturally EUS-affected snakeheads, snakeheads with healing lesions and apparently healthy snakeheads, but not from naïve snakeheads. The results provide evidence of a waterborne horizontal transmission of the EUS-associated virus. This is the first report of a successful horizontal transmission of the EUSassociated virus from apparently healthy snakeheads to naïve fish under natural conditions and of virus recovery in tissue culture from naturally exposed experimental fish.
    • Article

      Hormonal changes accompanying sexual maturation in captive milkfish (Chanos chanos Forsskal) 

      CL Marte & TJ Lam - Fish Physiology and Biochemistry, 1992 - Springer Verlag
      Steroid hormone profiles accompanying sexual maturation in captive milkfish are described. There were no significant differences in levels of serum estradiol 17-β (E2) and testosterone (T) between immature male and female fish. Mean E2 levels rose from 0.54±0.11 ng/ml in immature females (Stage 1) to 4.53±1.16 ng/ml in vitellogenic females (Stage 5), while T levels increased from 2.06±0.28 ng/ml to 38.4±9.26 ng/ml. E2 and T levels were positively correlated to GSI and oocyte diameter. In males, serum T levels increased from 2.5±0.40 ng/ml in immature males to 27.73±5.02 ng/ml in spermiating males. A significantly higher T level was found in males with thick and scantly milt (spermiation index, SPI, 2) compared to males with scanty milt (SPI, 1) or males with copious, fluid milt (SPI, 3).

      Serum levels of E2 and T, and the GSI in females rose significantly during the breeding season (April–June 1983). The levels of both steroids dropped below 1 ng/ml in spent females sampled in succeeding months. In immature males, T levels ranged from 1.11 ng/ml to 2.78 ng/ml and rose significantly to 21.52±8.38 ng/ml during the breeding season when GSI peaked. Serum T levels dropped to around 10 ng/ml in the succeeding months when only spent or regressed males were sampled.
    • Article

      Hormone-induced spawning and embryonic development of the rabbitfish, Siganus vermiculatus (Pisces: Siganidae) 

      EM Avila - The Philippine Scientist, 1984 - San Carlos Publications, University of San Carlos
      Induced spawning experiments were conducted on captive Siganus vermiculatus with the use of human chorionic gonadotropin (HCG APL Ayerst). The hormone was administered intramuscularly and the intraovarioan oocyte development and milt conditions of the fish were monitored by in vivo methods. Likewise, the spawning behavior and early life history of the species were observed and documented.

      Spontaneous spawnings and natural fertilization of the eggs occurred following ovulation in the fish injected with 500 IU HCG between 17 and 18 hrs after the last of a series of injections delivered at 24-hour intervals. Accelerated oocyte maturation was indicated by progressive changes in the gross morphological characters of the eggs and further thinning of milt. Dominant and aggressive behavior of the female characterized the spawning activities which commenced in the mornings.

      Newly-fertilized demersal eggs measured 0.52 ± 0.01 mm in diameter and each had a narrow perivitelline space, the yolk containing several centrally-located oil globules. Embyonic development was basically similar to that exhibited in most bony fishes. Atretic eggs retained in the body cavity averaged 0.57 ± 0.01 mm in diameter. Yolksac larvae, 1.75 ± 0.14 mm in standard length, hatched 23 to 24 hrs after fertilization in 25-25 ppt sea water at ambient temperature (25.9-28.1°C).
    • Article

      The hydraulic control structure: A threat to the fishpen industry in Laguna de Bay. 

      BH Nielsen, AE Santiago & F Petersen - Likas Yaman, Journal of the Natural Resources Management Forum, 1981 - Natural Resources Management Center
    • Article

      Hydrolyzed tuna meat by-product supplement for juvenile red sea bream, Pagrus major, and its effect on growth, enzyme activity, plasma parameters, and apparent nutrient digestibility 

      RE Mamauag, JA Ragaza, S Koshio, M Ishikawa & S Yokoyama - The Israeli Journal of Aquaculture-Bamidgeh, 2014 - Society of Israeli Aquaculture and Marine Biotechnology (SIAMB)
      A growth experiment was conducted on juvenile red sea bream, Pagrus major to investigate the effect of the inclusion in fish diets, of tuna meat by-product hydrolysate which was processed through enzymatic hydrolysis using a commercially available enzyme, derived from Bacillus subtilis. Six experimental diets were formulated in the experiment. Three diets contained 50, 150 and 250 g/kg of TPM-H (tuna meat by-product hydrolysate), and two diets with the unprocessed TPM (tuna meat by-product) at an inclusion level of 50 and 250 g/kg. A control diet was formulated without any addition of the test ingredients. Treatment diets were fed ad libitum to juvenile fish with an initial average body weight of 0.81 ±0.13 g for 56 days. Results of the feeding trial suggest that the inclusion of TPM-H at 250 g/kg in fish diets improved body weight gain rate (3271.58%), feed intake (24.55 g/fish/56 days) and feed conversion efficiency (1.12) of the fish. Apparent nutrient digestibility of hydrolyzed tuna meat by-product improved compared to the unhydrolyzed ingredient. These results suggest that TPM processed as hydrolysates can be efficiently utilized by fish.
    • Article

      Identification and characterization of vitellin in a hermaphrodite shrimp, Pandalus kessleri 

      ET Quinitio, A Hara, K Yamauchi, T Mizushima & T Fuji - Comparative Biochemistry and Physiology - B: Comparative Biochemistry, 1989 - Elsevier
      1. A female specific protein (FSP, vitellogenin) in hemolymph and its related ovarian protein (vitellin) of Pandalus kessleri were studied by means of electrophoretical and immunological procedures.

      2. The vitellin was purified from vitellogenic ovaries using hydroxylapatite, DEAE cellulose and Sepharose 6B columns, consecutively.

      3. The vitellin had a molecular weight of approximately 560 kD and was composed of two subunits, 81 and 110 kD, respectively.

      4. The vitellogenin concentrations in the hemolymph increased as vitellogenesis in the ovarian oocytes advanced and dropped markedly after the release of mature eggs.
    • Article

      Identification of postlarvae of the genus Penaeus appearing in shore waters 

      H Motoh & P Buri - Researches on Crustacea, 1981 - Carcinological Society of Japan
      Diagnostic features for the identification of postlarval Penaeus found in the shore waters of the Philippines are described and categorized based on specimens caught from the wild and those hatched and reared in the laboratory.

      Differentiating features for postlarval Penaeus are given which include the relative length of the antennular flagellum, the shape of the rostrum and number of rostral teeth, the antennal spine, the spinules on the dorsal caina of the sixth abdominal segment, and chromatophore patterns.

      Postlarval Penaeus were classified into two species and two groups as follows: (1) P. monodon, larger in size with dense chromatophores, and the long inner antennular flagellum being more than 2.0 times the outer antennular flagellum; (2) P. semisulcatus, the inner flagellum being 1.6 to 2.0 times the outer antennular flagellum, the the absence of chromatophore on the middle portion of the telson and uropods; (3) P. merguiensis group, less pigmented, the inner flagellum being less than 1.6 times the outer flagellum and (4) P. japonicus group, a short rostum, presence of spinules on the dorsal carina of the sixth abdominal segment, and dense chromatophores. The determinations were confirmed by rearing experiments.
    • Article

      Identification of Pseudomonas sp. strain S3 based on small subunit ribosomal RNA gene sequences. 

      AAA Hamid, S Hamdan, RV Pakingking Jr. & F Huyop - Biotechnology, 2010 - Asian Network for Scientific Information
      Pseudomonas sp. strain S3 was isolated from Paddy (rice) field agricultural area. This organism, which can utilize a halogenated compound of D,L-2-Chloropropionic acid as sole carbon and energy source, catalyses the hydrolytic dehalogenation of both D- and L- isomers of 2-Chloropropionic acid. Identification of Pseudomonas sp. S3 is still ambiguous due to the lack of basic studies, especially their molecular genetic information. In this study, the amplified 16S rRNA gene sequence of Pseudomonas sp. S3 (Accession No. FJ968758) was compared to other nine selected gene sequences from the same group of Pseudomonas sp. and/or dehalogenase producing bacteria using in silico method. Their phylogenetic relationships were then determined. The results were analysed using MEGA4 software to ascertain its evolutionary distance by reconstructing a phylogenetic tree of these organisms. The evolutionary history and bootstrap consensus tree were inferred using the Neighbour-Joining method from 500 replicates. The tree is drawn to scale, with branch lengths (next to the branches) in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The evolutionary distances were computed using the p-distance method and were in the units of the number of base substitutions per site. Based on this analysis, Pseudomonas sp. S3 16S rRNA gene was closely related to the Pseudomonas chlororaphis with genetic distance 0.170 base substitutions per site. S3 gene was also compared among known dehalogenase producing bacteria 16S rRNA genes. Results suggested that S3 was closely related to the Pseudomonas sp. R1 with a genetic distance 0.040 base substitutions per site. From present study, evolutionary relationships of 16S rRNA gene of Pseudomonas sp. S3 were elegantly illustrated by phylograms, comparable to a pedigree showing which microorganisms are most closely related.