Now showing items 1346-1365 of 3384

    • Article

      GABA enhances reproduction of the rotifer Brachionus plicatilis Muller: application to mass culture 

      WG Gallardo, A Hagiwara & TW Snell - Aquaculture Research, 2000 - Wiley-Blackwell
      Based on the results of individual and batch culture experiments in small volumes, we conducted experiments in larger volumes of 100 mL, 1 L and 10 L to determine: (1) at what phase of population growth would gamma-aminobutyric acid (GABA) treatment be most effective; and (2) whether GABA treatment of concentrated rotifers for several hours before mass culture would also be effective. GABA treatment of rotifer cultures at lag phase significantly enhanced population growth, whereas treatment at log phase had a lesser effect, and treatment at stationary phase had no effect. Addition of GABA to rotifer cultures every 2 days hastened population growth until day 8, but resulted in culture collapse thereafter. To reduce the cost of the use of GABA in mass cultures, GABA treatment may be conducted on concentrated rotifers (100 individuals mL−1) before mass culture. GABA treatment of concentrated rotifers for 24 h and 48 h before mass culture resulted in a significantly higher population density compared with their respective controls (no GABA treatment) on day 4, and on days 4 and 6 respectively.
    • Article

      GABA, 5-HT and amino acids in the rotifers Brachionus plicatilis and Brachionus rotundiformis 

      WG Gallardo, A Hagiwara, K Hara, K Soyano & TW Snell - Comparative Biochemistry and Physiology - Part A: Molecular and Integrative Physiology, 2000 - Elsevier
      γ-Aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT) have been shown to increase the reproduction of the Brachionus plicatilis (NH3L strain). In the present study, the endogenous presence of GABA and 5-HT in the rotifers B. plicatilis (NH3L and Kamiura strains) and Brachionus rotundiformis (Langkawi strain) were confirmed by dot blot immunoassay and high-performance liquid chromatography (HPLC). HPLC showed that GABA and 5-HT concentrations in the three rotifer strains range from 71 to 188 pmol/mg and from 12 to 64 pmol/mg, respectively. A total of 33 amino acids were also detected in B. plicatilis and B. rotundiformis, with glutamic acid, serine, glycine, taurine, threonine, alanine, arginine, proline, valine and isoleucine in high concentrations relative to other amino acids.
    • Article

      Gathering of economically important seaweeds in Western Visayas, Philippines 

      AQ Hurtado-Ponce, MRJ Luhan & NG Guanzon Jr. - The Philippine Scientist, 1992 - San Carlos Publications
      A survey was conducted in 12 coastal municipalities of Western Visayas, Philippines from March to July 1990 to determine the seaweed gathering practices of fishermen. There were 83 gatherers involved in this small-scale industry, who live below the poverty line and who consider it as the number one minor source of income. Only seaweeds of commercial value are gathered in big volume. There were approximately 114 T year-1 of seaweeds harvested from natural stock with a market value of P414, 950.00 ($14,819.64). The harvest is broken down into 3 main groups: (1) agarophytes, 99.5 T (Gelidiella, Gracilaria and Gracilariopsis), (2) carrageenophytes, 10 T (Eucheuma and Kappaphycus) and (3) table vegetable, 10 T (Caulerpa). An average maximum income of P5,600.00 or $200 gatherer-1 season-1 is derived from seaweed gathering.
    • magazineArticle

      GATT issues and Philippine agriculture 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1994 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Article

      Genetic assessment of milkfish (Chanos chanos Forsskal) stocks based on novel short tandem repeats for marker-aided broodstock management 

      MRR Romana-Eguia, BS Santos, M Ikeda, ZU Basiao & A Kijima - Aquaculture Research, 2018 - John Wiley and Sons
      Milkfish hatchery broodstock are either from on-grown wild-caught or hatchery-produced fry/juveniles. To determine if a marker-assisted management scheme can be formulated for improved milkfish hatchery production, milkfish stocks were genetically characterized using nine novel short tandem repeats or microsatellites. Eight wild-bred Philippine stocks (CLA, CUR, CAM, SIH, SBH-I1, HH, PAL and ZH-P0), four hatchery-bred stocks (SBH-I2, SBH-D, BoH and ZH-F1), two farm stocks of known mixed lineages (SPH and BDH) and one Indonesian hatchery-bred stock (WJH) were assessed. WJH was included since milkfish fingerlings from Indonesia reared in Philippine farms could be developed into future broodstock. Mean allelic richness (Ar) was highest in wild-bred stocks (9.5) and lowest in hatchery-bred spawners (9.1). Mean expected heterozygosities (He) were relatively similar in all stocks with wild-bred stocks slightly higher (0.67) than the others. An analysis of molecular variance indicated significant yet low genetic differentiation among stocks (FST = 0.013; p = .000) where variation (98.6%) was explained by intra-stock differences. In some of the domesticated stocks, reductions in mean allelic richness were observed in first generation hatchery broodstock (e.g. ZH-F1; Ar = 8.3), compared with their founder stock (e.g. ZH-P0; Ar = 9.4). The Indonesian stock was similar to local wild-bred stocks based on genetic variability indices; thus, it might be likely that the local stocks’ fitness traits could be comparable with the imported milkfish stock which has been perceived to be better. The quality of locally available farmed milkfish and prospects of formulating a broodstock management scheme for the production of good quality milkfish seedstock are herewith discussed.
    • Oral presentation

      Genetic changes during development of penaeid shrimp. 

      JL Lester - 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
      As penaeid shrimp grow from the earliest naupliar stages, through protozoeal and mysis stages, to postlarvae, they develop greater morphological and behavioral resemblance to the adults. Electrophoretic analysis of cytoplasmic enzymes from nauplii, protozoea, mysis, postlarvae, and adults show that each stage has a unique pattern of gene activity. Thirteen enzyme stains and a general protein stain have been used on larval samples from Penaeus stylirostris, P. vannamei and P. aztecus. Some enzymes, such as phospho-glucose isomerase, are produced in the same isozymic form during all of the stages. Other enzymes exhibit changes in the number and position of isozymic bands during development, e.g. glutamate dehydrogenase. Some of these differences among developmental stages can only be explained by changes in the number and/or identity of the genes that are active at each stage. This finding suggests larval and adult responses to selection may be relatively independent.
    • Article

      Genetic changes during mass selection for growth in Nile tilapia, Oreochromis niloticus (L.), assessed by microsatellites 

      MRR Romana-Eguia, M Ikeda, ZU Basiao & N Taniguchi - Aquaculture Research, 2005 - Blackwell Publishing
      Two control (C1 or first control generation, and C4 or fourth control generation) and three selected (S1 or first selected generation, S2 or second selected generation, S4 or fourth selected generation) stocks of Chitralada Nile tilapia were analysed for microsatellite variation to determine the effect of size-specific mass selection on genetic variability. Genetic variation based on five microsatellite loci (UNH123, UNH147, UNH172, UNH222 and UNH216) showed a slightly higher allelic diversity in the selected stocks (7.4–10 alleles) than in the control stocks (6.8–8.8 alleles). Apparent reductions in the mean number of alleles and He values were noted in successive generations of both control and selected lines. Significant deviations from Hardy–Weinberg equilibrium because of an excess of homozygotes indicated inbreeding in all control and selected stocks. Although estimated inbreeding levels were not significantly different among selected and control lines based on Welch's t-tests, the increase in the degree of inbreeding within the selected line was higher (107.9%) than the control line (64.2%) after four generations. The implications of these results on the management and conservation of genetic diversity in improved breeds are discussed, while the importance of monitoring and minimizing inbreeding are likewise emphasized.
    • Conference paper

      Genetic diversity and stock delineation of Philippine populations of the orange mud crab, Scylla olivacea 

      FJM Paran & RJ Ravago-Gotanco - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The orange mud crab, Scylla olivacea, is regarded as an important fishery resource due to high demand and high market value. However, mud crab populations are threatened by over exploitation and habitat degradation, and would benefit from resource management interventions. The study examined patterns of genetic diversity and connectivity of orange mud crab populations across the Philippines, with the aim of identifying putative management units. A total of 387 Scylla olivacea were collected from ten localities across the Philippine archipelago. Phylogenetic analysis of mitochondrial control region (mtDNA-CR) DNA sequences revealed cryptic diversity among Scylla olivacea specimens with four mitochondrial lineages recovered. Analysis of molecular variance revealed that Philippine populations do not constitute a single genetic stock (0ST=0.00262; P=0.00015). Thirteen microsatellite loci were also utilized as additional markers to infer population structure and estimate genetic variation. Overall, S. olivacea populations exhibit high haplotype diversity (mean h=0.9803) and nucleotide diversity (mean ~p3.46%), which may be indicative of a large, stable population within Philippine archipelagic waters. This study provides information on genetic diversity and population structure of S. olivacea, which will be useful towards developing management and conservation strategies for sustainable development of natural S. olivacea populations in the Philippines.
    • Article

      Genetic diversity in farmed Asian Nile and red hybrid tilapia stocks evaluated from microsatellite and mitochondrial DNA analysis 

      MRR Romana-Eguia, M Ikeda, ZU Basiao & N Taniguchi - Aquaculture, 2004 - Elsevier
      We analyzed microsatellite and mitochondrial DNA restriction fragment length polymorphism (mtDNA-RFLP) in two domesticated (NIFI and Israel) and four genetically improved (GIFT, GMT, FAC-selected and SEAFDEC-selected) Nile tilapia (Oreochromis niloticus) as well as five red hybrid tilapia (Oreochromis mossambicus × O. niloticus) stocks (BFS, FACred, NIFIred, HL, and PF) farmed in Asia. Microsatellite variation at five loci (UNH216, UNH172, UNH123, UNH147, UNH222) was more informative in characterizing stock differences than the mtDNA-RFLP markers that were based only on 14 restriction morphs. Contemporary microsatellite data showed that GIFT Nile tilapia had the highest mean expected heterozygosity (H>e=0.813), while GMT had the lowest (He=0.666). The unselected NIFI stock and SEAFDEC-selected were genetically similar, while GMT differed significantly from the other Nile tilapia stocks. Among the red tilapias, NIFIred had the highest He (0.715), while BFS had the lowest variability (He=0.567). The Taiwanese red tilapia HL and Thai NIFIred were genetically similar. Except for NIFI, most of the Nile and red tilapia stocks exhibited remarkably significant homozygote excess relative to Hardy–Weinberg Equilibrium (HWE), suggesting some degree of inbreeding. Asian Nile tilapias were more genetically diverse (pooled He=0.791; mtDNA nucleotide divergence value dA=0.009) than the red tilapias (pooled He=0.697; mean dA=0.004). This slight divergence between the Nile and red tilapias was also seen in the analysis of molecular variance (AMOVA; FCT=0.0018) and in genetic distance and nucleotide divergence dendrograms. However, the AMOVA revealed that the greater percentage of variation (99.33%) in the total genetic diversity of the surveyed stocks is principally due to differences at the individual level and not between nor within groups. The significance of these results is that they reflect and lead to new inferences regarding the selective breeding and culture methods used in managing these farmed stocks.
    • Article

      Genetic diversity of wild and cultured Black Tiger Shrimp (Penaeus monodon) in the Philippines using microsatellites 

      Z Xu, JH Primavera, LD de la Peña, P Pettit, J Belak & A Alcivar-Warren - Aquaculture, 2001 - Elsevier
      Six microsatellites were used to study (1) the genetic diversity of wild Penaeus monodon shrimp from four geographic regions (Palawan, Quezon, Capiz and Negros Occidental-W) in the Philippines, and (2) its association with the status of mangroves and intensity of shrimp culture systems in these regions. Two cultured populations (Negros Occidental-C and Antique) were used for comparison. All six microsatellite loci were polymorphic. A total of 184 different alleles were found over all loci. The total number of alleles per locus ranged from 6 to 54, with allele size ranging from 159 base pairs (bp) to 400 bp. The observed heterozygosity of the six loci ranged from 0.47 to 1.00. The number of genotypes per locus ranged from 5 to 70. Fst values showed significant genetic differentiation among the four wild populations. Genetic differences between wild populations were also detected by pairwise comparison based on genotypic and allelic frequencies. Genetic differentiation among wild populations exhibited a positive correlation with mangrove status and intensity of culture systems at P=0.083. The Negros Occidental-W population, which originated from an area with the most severe mangrove loss and the most intensive culture systems, was the most significantly differentiated population. It also showed less genotypes per locus than the other three wild populations, suggesting a decrease in genetic diversity in this population. The population from Capiz, a province with a wide area of extensive culture ponds and few remaining secondary mangroves was the second most differentiated population. The Quezon population, which originated from an area with a few extensive culture ponds and less mangrove destruction, was not genetically different from the Palawan population, which was from a pristine site with mostly primary mangroves and no major aquaculture industry. The cultured populations showed less genetic diversity and were significantly different from the four wild populations based on pairwise Fst values and pairwise comparisons of allelic and genotypic frequencies. The results suggest that (a) there was a significant genetic differentiation among the wild P. monodon populations in the Philippines, and (b) the cultured populations were significantly differentiated from the natural populations. More replicate samples from each of the geographic regions are needed to conclusively determine the possibility of an association between genetic differentiation and the status of mangroves and/or intensity of shrimp culture systems.
    • magazineArticle

      The genetic garden 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1995 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The article discusses some strategies in the establishment of a mangrove genetic garden where species could be maintained. The genetic garden is a sustainable way to prevent further damage of the remaining mangroves. Its prime function is the protection and conservation of mangroves for sustainable use.
    • Book chapter

      The genetic improvement of farmed tilapias project: Impact and lessons learned 

      BO Acosta & MV Gupta - In SS De Silva & FB Davy (Eds.), Success Stories in Asian Aquaculture, 2010 - Springer
      In response to challenges that the developing world confront on food security and malnutrition, the last two decades have witnessed increased efforts in genetic improvement to enhance production traits of commercially important aquatic species. From the 1980s to the present, several institutions in developing countries have been engaged in such R&D activity and it is recognized that the collaborative program on Genetic Improvement of Farmed Tilapias (GIFT) has spurred the development of several tilapia and carp breeding programs that now exist in numerous developing countries. The GIFT is a collaborative R&D program conducted by the WorldFish Center (formerly, International Center for Living Aquatic Resources Management, ICLARM) and its partners from the Philippines and Norway aimed to develop methodologies for the genetic improvement of tropical finfish of aqua-culture importance. The GIFT project has demonstrated that selective breeding is a feasible, cost effective, and sustainable approach to the genetic improvement of tropical finfish, and also confirmed the importance of a multidisciplinary approach that enabled the assessment of economic viability, social acceptability, and environmental compatibility, thus, creating confidence among planners and administrators, all of which facilitated the transfer of research findings to farming systems in a host of countries. The program and its successors, such as the International Network on Genetics in Aquaculture (INGA), demonstrated that networking and partnership building among national institutions in developing countries, advanced scientific institutions, and regional and international organizations can play a major role in accelerating research and the success of R&D.
    • Meeting report

      Genetic improvement of Macrobrachium rosenbergii in Indonesia. 

      E Nugroho, K Sugana & Mr. Maskur - 2005 - Aquaculture Department, Southeast Asian Fisheries Development Center
      One way of increasing the production of freshwater prawn is through a genetic improvement program. The GI Macro seeds (Genetically Improved Macrobrachium rosenbergii) that Indonesia developed have been released to farmers since 2001. However, producing 50 g prawns have become difficult with survival rate of as low as 40% after 9-11 months of culture. Thus, the program to improve growth rate and increase the edible portion of the prawn was conducted.

      Giant freshwater prawn is an important commodity that is successfully cultured in Indonesia. Its culture has been developed in several areas of West Java, i.e., Ciamis (Tambaksari, Pamarican and Kalipucang) and Tasikmalaya. The Indonesian Government has developed a hatchery in Jogjakarta province (Central Java), while the private sector control about seven hatcheries. In East Java, freshwater prawn is cultured in brackishwater ponds. Freshwater prawn culture has also spread to some areas of Bali Island, e.g., in Gianyar, Klungkung, Buleleng and Tabanan.

      Indonesia has been recognized as the center of origin of the giant freshwater prawn because about 19 identified species are found in almost all islands of the country (Holthuis, 1980). However, this genetic resource is not yet fully used in freshwater prawn culture. Although freshwater prawn culture has been widely developed in Indonesia, some problems have been encountered, e.g., declining growth rate, disease, and the small edible portion (abdominal muscle).

      In recent years, the Government of Indonesia has stressed the need to increase the production of freshwater prawn. One way to increase production is through the genetic improvement program. In 2001, the GI Macro (Genetically Improved Macrobrachium rosenbergii), strain of freshwater prawn has been developed and released to farmers.
    • magazineArticle

      Genetic, species, and ecosystem diversity 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1994 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Article

      Genomic polymorphism in symbiotic populations of Photobacterium leiognathi 

      PV Dunlap, A Jiemjit, JC Ast, MM Pearce, RR Marques & CR Lavilla-Pitogo - Environmental Microbiology, 2004 - Blackwell Publishing
      Photobacterium leiognathi forms a bioluminescent symbiosis with leiognathid fishes, colonizing the internal light organ of the fish and providing its host with light used in bioluminescence displays. Strains symbiotic with different species of the fish exhibit substantial phenotypic differences in symbiosis and in culture, including differences in 2-D PAGE protein patterns and profiles of indigenous plasmids. To determine if such differences might reflect a genetically based symbiont-strain/host-species specificity, we profiled the genomes of P. leiognathi strains from leiognathid fishes using PFGE. Individual strains from 10 species of leiognathid fishes exhibited substantial genomic polymorphism, with no obvious similarity among strains; these strains were nonetheless identified as P. leiognathi by 16S rDNA sequence analysis. Profiling of multiple strains from individual host specimens revealed an oligoclonal structure to the symbiont populations; typically one or two genomotypes dominated each population. However, analysis of multiple strains from multiple specimens of the same host species, to determine if the same strain types consistently colonize a host species, demonstrated substantial heterogeneity, with the same genomotype only rarely observed among the symbiont populations of different specimens of the same host species. Colonization of the leiognathid light organ to initiate the symbiosis therefore is likely to be oliogoclonal, and specificity of the P. leiognathi/leiognathid fish symbiosis apparently is maintained at the bacterial species level rather than at the level of individual, genomotypically defined strain types.
    • Article

      Genotype environment interaction in the response of three strains of Nile tilapia to poor nutrition 

      MRR Romana-Eguia & RW Doyle - Aquaculture, 1992 - Elsevier
      Experiments were conducted to determine the effects of poor nutrition on the growth of three Oreochromis niloticus strains fed protein-deficient diets. Four-week-old fry from the three "test" strains were paired with a fourth "reference" strain of tilapia (red) of the same size and stocked in 60-1 aquaria. The treatment lasted 6 weeks, with fish being fed commercial fish feed crumbles for the first and last 2-week periods and rice bran during weeks 3 and 4. Control fish were fed commercial diet throughout. Both control and treatment fish were fed at 20% of fish biomass per day. Lengths and weights were measured every 2 weeks.

      Significant strain effects were noted when the growth of test fish over the whole experimental period was analysed by analysis of covariance using the reference fish growth as a concomitant variable. The relative growth of the three test strains differed at each feeding phase. The NIFI strain grew best during the commercial feed phases, the Israel strain performed best during the rice bran phase while the CLSU strain, regardless of the type of nutritional environment, usually ranked last. Different performance rankings at each feeding phase represent strong genotype X environment interaction among these commercially important lines. This was statistically confirmed by analysis of covariance of the growth of the Israel and NIFI strains during the different feeding phases using the reference strain as a covariate.
    • Article

      The genus Gracilariopsis (Rhodophyta, Gracilariales) in the Philippines: morphological and taxonomic confirmations 

      AQ Hurtado-Ponce & LM Liao - The Philippine Scientist, 1998 - University of San Carlos
      Reports of the economically-important agarophytic seaweed genus Gracilariopsis Dawson from Philippine waters are verified for the first time. Cystocarpic, spermatangial and tetrasporic materials collected from various localities in eastern Panay and northwestern Negros islands conform to the circumscription of this recently reinstated genus. Materials are referred to Gracilariopsis heteroclada Zhang & Xia after morphological comparisons with type materials from southern China. In addition, a discussion of the complicated nomenclatural history of this species is included.

      Another putative Gracilariopsis species is reported from Zamboanga City based on cystocarpic materials alone. This species differs from G. heteroclada with its smaller gonimoblast cells and larger height:width ratio of the gonimoblast mass. Vegetatively, the thallus is smooth, devoid of fine, determinate branchlets observed in G. heteroclada.
    • magazineArticle

      Getting innovations from fieldwork 

      MB Surtida - SEAFDEC Asian Aquaculture, 1997 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • magazineArticle

      Getting the fishfarm ready and then operating it 

      M Castaños - SEAFDEC Asian Aquaculture, 2000 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Book

      Giant clam hatchery, ocean nursery and stock enhancement 

      SS Mingoa-Licuanan & ED Gomez - 2007 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 37
      This manual is meant to serve as a guide to the culture of giant clams (Bivalvia, Subfamily Tridacninae). The first part focuses on hatchery methods. The second part is about the ocean nursery. The first two sections refer to selection and setting the ocean nursery site. Clam transport is introduced next although this is further tackled in the last part of this manual. Finally, the third and last part discusses the purposes of stock enhancement, survey methods for stock assessment, transport, monitoring and record keeping.