Now showing items 3191-3210 of 3262

    • 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 Aujero & O Millamena - SEAFDEC Aquaculture Department Quarterly Research Report, 1979 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Freezing with added chemicals as flocculants and protectants was assessed as a means of preserving stock cultures of 4 algal species used for larval penaeid food Chaetoceros calcitrans, Skeletonema costatum, Tetraselmis chuii and Isochrysis galbana . The maximum storage effectability of the preservation techniques for each species was also determined.
    • 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.
    • Conference paper

      Viability of milkfish eggs and larvae after simulated and actual transport 

      JD Toledo, M Doi & M Duray - In D MacKinlay & M Eldridge (Eds.), The Fish Egg: Its Biology and Culture Symposium Proceedings. International Congress on the Biology of Fishes, 14-18 July 1996, San Francisco State University, 1996 - American Fisheries Society, Physiology Section
      The viability of milkfish eggs and larvae after simulated and actual transport was investigated. Naturally-spawned milkfish eggs were collected and subjected to simulated or actual transport at early cleavage stage (stage 1), blastula (stage 2), gastrula (stage 3), "eyed" (stage 4), or newly-hatched larvae (stage 5). Replicate samples in aerated plastic jars served as controls. Mean hatching and survival rates and the percentage of newly-hatched larvae were significantly affected by the modes of transport and by the stage of embryonic development at transport. Eggs transported at the 'eyed' stage had higher viability compared to those transported at cleavage, blastula, or gastrula stages. There was no significant difference in the mean survival rate of the larvae after 26 days of rearing. However, the percentage of 45 day old larvae with apparent morphological abnormalities was lower in groups transported at stages 4 and 5. These observations indicate that milkfish eggs should be handled and transported during the late embryonic stages to minimize mortalities and the incidence of abnormalities in larvae.
    • Article

      Viability of Penaeus monodon eggs after simulated transport conditions 

      JH Primavera, E Borlongan & RA Posadas - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      P. monodon spawners, transported from maturation pens suffer from stress which in turn may lead to lowered spawning rate or fertility. Spawning the females in the maturation site and transporting the eggs to the hatchery site is being considered as an alternative. Egg transport costs may be reduced to a minimum by using eggs from ablated spawners, transported at high density with no aeration. Experiments on higher egg densities as well as on transport of nauplii should, however, be undertaken.
    • Conference paper

      Vibrio harveyi and the 'green water culture' of Penaeus monodon. 

      GD Lio-Po, EM Leaño, RC Usero & NG,J Guanzon - In Y Inui & ER Cruz-Lacierda (Eds.), Disease Control in Fish and Shrimp Aquaculture in Southeast Asia – Diagnosis and Husbandry Techniques: Proceedings … Aquaculture in Southeast Asia – Diagnosis and Husbandry Techniques, 4-6 December 2001, Iloilo City, Philippines, 2002 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The 'green water culture' of the tiger shrimp, Penaeus monodon, is an innovative culture technique for the grow-out rearing of shrimps. This culture method involves the use of rearing water of tilapia for the rearing of tiger shrimp in grow-out ponds and on the polyculture of shrimp with tilapia. This culture technique was reported to present disease outbreaks attributed to luminescent Vibrio. To understand the possible mechanisms of luminous Vibrio control in the green water culture system several studies were conducted. This review summarizes the highlights obtained so far from these studies consisting of a) effect of rearing waters from tilapia culture and shrimp cultured with tilapia on Vibrio harveyi; b) estimation and preliminary identification of cultivable bacteria, fungi and phytoplankton flora associated with the 'green water culture' system and c) detection of anti-Vibrio harveyi metabolites from bacteria, yeast, filamentous fungi and phytoplankton indigenous to the 'green water culture' system.
    • 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.
    • Conference paper

      Viet Nam: Mangrove-friendly aquaculture 

      TT Luu - In JH Primavera, LMB Garcia, MT Castaños & MB Surtida (Eds.), Mangrove-Friendly Aquaculture : Proceedings of the Workshop on Mangrove-Friendly Aquaculture organized by the SEAFDEC Aquaculture Department, January 11-15, 1999, Iloilo City, Philippines, 2000 - Southeast Asian Fisheries Development Center, Aquaculture Department
    • Conference paper

      Vietnam: status of implementation of the resolution and plan of action on aquaculture. 

      LT Luu - In BO Acosta, RM Coloso, EGT de Jesus-Ayson & JD Toledo (Eds.), Sustainable aquaculture development for food security in Southeast Asia towards 2020. Proceedings of the Regional Technical Consultation on Sustainable Aquaculture Development in Southeast Asia Towards 2020, 2011 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Aquaculture in Vietnam achieved significant increase in production from 425,000 mt in 1998 to 2,465,600 mt in 2008 and this has contributed to addressing the country s food security agenda. This achievement has indicated success of a number of factors including implementation of appropriate policies, technological improvements in aquaculture, efficiency of extension work, and capacity of market expansion. Improvement of seed production and supply through strengthening the infrastructure of hatchery system throughout the country and diversification of culture species have contributed to achieving the goal of aquaculture development programs for the period 1999-2010. The challenge on the use of fish meal is being addressed by using the omnivorous fish species such as the carps, tilapias, pangasius and mollusks for large-volume production. Environment-friendly technologies are developed and applied in aquaculture practices. Good aquaculture practices and Best management practices have encouraged the different stakeholders (seed producers, growers, feed suppliers) to apply these practices in their business. Aquaculture is seen as an important sector for rural development because this contributes significantly to income and employment for rural population, on one hand, and better use of land (where agriculture operation is not economically feasible) and water resources, on the other hand. Nevertheless, aquaculture in Vietnam is still faced with a number of issues which need to be addressed and these are as follows: (a) capacity to guide sustainable aquaculture; (b) appropriate policies to fit into new development trends; (c) quality of economically important species; and (d) traceability, certification and linkage to market chain of small scale producers. Some important points of aquaculture development plan in Vietnam during the period 2011-2020 are also introduced in this paper.
    • Conference paper

      Viewpoint on formulating policies for sustainable shrimp culture 

      WG Yap - In Bangkok FAO Technical Consultation on Policies for Sustainable Shrimp Culture, Bangkok (Thailand), 8-11 Dec 1997, 1999 - Rome, Italy: Food and Agriculture Organization of the United Nations
      Series: FAO Fisheries Report No. 572
      An examination is made of all the negative impacts attributed to shrimp culture, particularly to intensive culture, considering also remedial measures recommended to ameliorate their ill-effects and discussing the implications and practicability of the suggested measures. The following impacts are covered: loss of mangrove ecosystems; organic loading and pollution; nutrient enrichment and eutrophication; the use of bio-active materials; longevity and toxicity of chemicals to non-target species; development of antibiotic resistance; species introduction and spread of disease; decline in natural stock of shrimps and other species; water and soil salinization and land subsidence; privatization of resources; competition for land, credit and commercial products; decline in domestic food crops; and, the 'fish meal trap'.
    • magazineArticle

      Village level processing techniques 

      MB Surtida - SEAFDEC Asian Aquaculture, 1998 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The agar-bearing seaweeds Gracilaria and Gelidium grow abundantly in the Asia-Pacific region. Production and post-harvest techniques and methods for processing Gracilaria to produce agar suitable for local market is necessary to increase the meager income of coastal dwellers. A flow diagram of a village level agar production is provided. A guide is also given for the quality of dried seaweeds, which are divided into 3 classes.
    • magazineArticle

      A village level technology of extracting agar 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1991 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • magazineArticle

      A village's link to the world market economy 

      SV Siar - SEAFDEC Asian Aquaculture, 2000 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Book chapter

      Viral diseases 

      GD Lio-Po - In GD Lio-Po, CR Lavilla & ER Cruz-Lacierda (Eds.), Health Management in Aquaculture, 2001 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Outbreaks of viral infections can cause massive mortalities among cultured fishes or shrimps. Water temperature and age of the fish or shrimps are significant factors that influence the development of viral infections. Most fish viral infections occur at low water temperatures, hence, very few viral infections among fishes in warm water culture systems are reported. In addition, most viral infections occur among fry or fingerlings often causing severe mortalities, while older fish or shrimp develop resistance or are hardly affected. Stress from handling, poor water quality, high stocking density and poor nutrition also affect the severity of viral infections. Finally, aquaculturists should beware in importing non-indigenous fish or shrimps into the country as these are potential carriers of viral pathogens.
    • Book chapter

      Viral diseases 

      GD Lio-Po - In GD Lio-Po & Y Inui (Eds.), Health Management in Aquaculture, 2010 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Outbreaks of viral infections can cause massive mortalities among cultured fishes or shrimps. Water temperature and age of the fish or shrimps are significant factors that influence the development of viral infections. Most fish viral infections occur at low water temperatures, hence, very few viral infections among fishes in warm water culture systems are reported. In addition, most viral infections occur among fry or fingerlings often causing severe mortalities, while older fish or shrimp develop resistance or are hardly affected. Stress from handling, poor water quality, high stocking density and poor nutrition also affect the severity of viral infections. Finally, aquaculturists should beware in importing non-indigenous fish or shrimps into the country as these are potential carriers of viral pathogens.
    • Book chapter

      Viral diseases 

      GD Lio-Po & LD de la Peña - In K Nagasawa & ER Cruz-Lacierda (Eds.), Diseases of cultured groupers, 2004 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Some viral infections are serious diseases of groupers causing heavy mortalities. In most cases, larval stages are the most susceptible stage. With the carnivorous nature of groupers, they can readily ingest viral pathogens from live fish food or trash fish that carry the viral pathogens. Moreover, viruses are able to effect vertical transmission from broodstocks that are likely carriers of the virus. Survivors of viral epizootics can be carriers of viral pathogens.

      This chapter focuses on current information on the major viral infections of groupers, i.e., viral nervous necrosis (VNN) and viral infections attributed to the family Iridoviridae.
    • Book chapter

      Viral diseases of shrimp in the Philippines 

      KGS Andrino-Felarca, EG Estante & CC Lazado - In CMA Caipang, MBI Bacano-Maningas & FF Fagutao (Eds.), Biotechnological Advances in Shrimp Health Management in the Philippines, 2015 - Research Signpost
      Shrimp is a high-value commodity and one of the major aquaculture species in the world, including the Philippines. The shrimp farming industry is dominated by the black tiger shrimp Penaeus monodon and the Pacific white shrimp, Penaeus vannamei. Intensification in shrimp aquaculture to meet the global demand resulted to several socio-economic and biophysical production bottlenecks. Consequently, the issues besetting the industry had raised several questions on its sustainability. In particular, viral diseases remain a constant threat and a significant concern in many shrimp producing countries especially in the developing world. In this chapter, current knowledge on major viral pathogens affecting shrimp aquaculture in the Philippines is presented and discussed. The discussion is focused on white spot syndrome virus (WSSV), monodon baculovirus (MBV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), hepatopancreatic parvovirus (HPV). yellow head virus (YHV), and taura syndrome virus (TSV). Updates on their clinical signs, transmission and distribution are presented. Records of incidence in the Philippines are provided as well. The second half of the chapter discusses some of the methods how to control viral diseases in shrimp farming with a particular focus on vaccination, biosecurity and diagnostics.