Now showing items 839-858 of 3350

    • Article | Short report

      Early appearance of the retinal tapetum, cones, and rods in the larvae of the African catfish Clarias gariepinus 

      G Kawamura, T Bagarinao, J Justin & CY Chen - Ichthyological Research, 2016 - Springer Verlag
      In the retina of the African catfish Clarias gariepinus, the pigment epithelium and the tapetum were formed in newly hatched larvae, the cones developed within 2 days, and the rods within 3 days after hatching. The retinal tapetum shone under surface light under a light microscope; the shine was located in the apical projections of the pigment epithelial cells. Early appearance of the retinal elements enables African catfish larvae to see and feed well even in dim light.
    • Book chapter

      Early development and seed production of Asian seabass, Lates calcarifer 

      EG de Jesus-Ayson, FG Ayson & V Thepot - In DR Jerry (Ed.), Biology and Culture of Asian Seabass Lates Calcarifer, 2014 - CRC Press
      This Chapter outlines the characteristics of L. calcarifer eggs and larvae, the changes during embryonic and larval development, advances in seed production and at the same time highlights the relative ease in its mass production.
    • Article

      Early development of Crassostrea iredalei (Faustino, 1932) (Bivalvia: Ostreidae), with notes on the structure of the larval hinge 

      LMM Ver - Veliger, 1986 - California Malacozoological Society, Inc.
      Larvae of the oyster Crassostrea iredalei were reared in the laboratory from eggs through settlement. The oysters were induced to spawn by increasing the temperature by 5-10°C and sometimes by adding stripped oyster sperm to the spawning dishes. Eggs avareaged 48 µm in diameter.

      The straight-hinge veligers appeared 22 to 26 h after fertilization. The larval shell length increased from 64 to 84 µm in the straight-hinge stage, from 85 to 275 µm in the umbo stage, and from 210 to 275 µm in the pediveliger stage. Eye-spotted pediveligers were observed mostly at lengths greater than 225 µm. The hinge line did not increase much with larval growth. Although length was initially greater than height, the increase in height was much faster due to the development of the umbo. Height was greater than length in more advanced larvae. Valve growth was asymmetrical and unequal, with the left valve generally larger. Settlement and metamorphosis occurred 20 days from fertilization at lengths of 270 µm and greater, when the oyster larvae were reared at 26.5 to 30°C and salinities of 30 to 32 ppt.

      The larval hinge structure consisted of minute dentition on the central portion of the provinculum and large rectangular teeth on both ends. These teeth became obscured in advanced larvae due to the skewed development of the umbo.

      Data derived from the laboratory culture of larvae of Crassostrea iredalei may be used in spatfall forecasts for the collection of larvae from the wild and as baseline information for the hatchery culture of oyster larvae.
    • Article

      Early development of fin-supports and fin-rays in the milkfish Chanos chanos 

      Y Taki, H Kohno & S Hara - Japanese Journal of Ichthyology, 1986 - The Ichthyological Society of Japan
      Development of fin-supports and fin-rays was observed in larval and juvenileChanos chanos, Chondrification of the caudal complex started at 4.70 mm SL. Ossification of the caudal elements started at 7.80 mm SL and was nearly completed at about 30 mm SL. Cartilaginous fusion of caudal elements, which occurs in hypurals of higher teleostean fishes but is not seen in lower teleosts, was observed between the neural arch of the preural centrum 1 and that of the ural centrum 1 via a small cartilage bridging the distal tips of the two arches. Caudal finrays began to develop at 6.60 mm SL, and an adult complement of principal rays was attained at 7.35 mm SL. Dorsal and anal pterygiophore elements were first evident at 6.70 mm and 6.65 mm SL, respectively. All proximal radiais were formed at 8.15 mm SL in both fins. Formation of dorsal and anal fin-rays started simultaneously at 8.60 mm SL, and adult fin-ray complements were attained at 10,00 mm and 10.70 mm SL, respectively. In the pectoral fin, the cleithrum, coraco-scapular cartilage and blade-like cartilage (fin plate) had already been formed at 4.65 mm SL. The mesocoracoid was observed to originate from the coraco-scapular cartilage and become detached from it in the course of ossification. Pectoral fin-ray formation started at 13.80 mm SL and was completed in number of rays at 20.00 mm SL. In the pelvic fin, the basipterygium was first evident at 13.00 mm SL. Pelvic fin-rays appeared at 13.80 mm SL and attained their adult count at 17.15 mm SL.
    • Article

      Early effects of nutritional stress on the liver of milkfish, Chanos chanos (Forsskal), and on the hepatopancreas of the tiger prawn, Penaeus monodon (Fabricius) 

      V Storch, JV Juario & FP Pascual - Aquaculture, 1984 - Elsevier
      After periods of food deprivation and subsequent feeding, hepatocytes of Chanos chanos fry and R-cells of Penaeus monodon juveniles were investigated by means of transmission electron microscope. They clearly reflect the quality of different diets and thus can be used as monitor cells. For purposes of comparison, the same diets were offered to land-dwelling isopods which are known to accept a variety of different diets. Thus, this technique could also be used as a method of determining the effectiveness of binders in artificial diets.
    • Article

      Early larval development of the seabass Lates calcarifer with emphasis on the transition of energy sources 

      H Kohno, S Hara & Y Taki - Nippon Suisan Gakkaishi, 1986 - Japanese Society of Fisheries Science
      The early growth, yolk and oil globule resorption, early morphological and behavioral de-velopment, and initial feeding of hatchery-raised Lates calcarifer were studied. Based on the developmental events and the energy the reby utilized, the early life history of this species can be broken down into the following five phases: 1) rapid early growth due to rapid yolk resorption (from hatching to about 15 hr after hatching (TAH); 2) morphological differentiation and slowgrowth based on energy from yolk (to about 50 h TAH when the yolk is exhausted); 3) slow growth with initiation of feeding and swimming activities, based on energy from oil globule and from exogenous food (to about 110 h TAH); 4) accelerated growth and effective feeding and swimming based on the same two sources of energy as in the preceding stage (up to about 120-140 h TAH when the oil globule is exhausted); and 5) accelerated growth, effective feeding and swimming and further development based solely on exogenous energy (beyond 140 h TAIT).
    • Book chapter

      Early ossification and development of the cranium and paired girdles of Chanos chanos (Teleostei, Gonorynchiformes) 

      G Arratia & T Bagarinao - In T Grande, FJ Poyato Ariza & R Diogo (Eds.), Gonorynchiformes and Ostariophysan Relationships: A Comprehensive Review, 2010 - Science Publishers
      In this chapter, we provide new data on the timing of ossification of cranial and paired girdle elements, and compare our results, when it is possible, with previous work on early ossification development of Chanos chanos. This is particularly important because of the basal phylogenetic position of Chanos among living ostariophysans and among extant gonorynchiforms as well (see Fig. 3.1). We describe the normal cranial and girdle patterns of ossification in Chanos chanos and evaluate to what extent the cranial development is consistent, or whether some intraspecific differences occur in comparison to previous results by Taki et al. (1987) and Kohno et al. (1996a) based on ontogenetic series grown in the same Aquaculture Department as the specimens used in this study. We assess previously published developmental work in a few ostariophysans and test some previous hypotheses on heretochrony and patterns of diversification. [A study of chondrification versus ossification processes in Chanos chanos is outside the scope of this paper, but it is the subject of a separate paper (Arratia and Grande, in preparation).]
    • Article

      Early postmysis stages of the giant tiger prawn, Penaeus monodon Fabricius 

      H Motoh & P Buri - Researches on Crustacea, 1980 - Carcinological Society of Japan
      The morphological development of the early postmysis stages of the giant tiger prawn, Penaeus monodon are described and illustrated using laboratory-reared specimens and wild ones.

      The first 3 or 4 substages are termed "megalopa" owing to the incomplete branchial formula of the mouth parts, their pelagic or planktonic behavior and their somewhat narrower body. At the 4th or 5th substage, the branchial formula is completed, their behavior is more or less epibenthic, the chromatophores are densely distributed from the tip of the antennular flagella through the ventral side of the abdomen to the tip of the telson. At the beginning of the 7th substage, the chromatophores are distributed over almost the whole body. Thus from the 4th or 5th substage onwards they may be termed juveniles.

      The main characteristics development are as follows : 1) The cempletion of the rostral spine formula appears in the 7th or 8th substage showing 7 dorsal and 3 ventral spines. 2) The endopod of the 1st maxilliped develops again at the 7th substage, although it degenerates with every molt prior to the 7th. 3) From the 1st substage, the distal 3 segments of the endopod of the 2nd maxilliped are bent sharply inwards.
    • Conference poster

      Earthworm, marine annelids and squid as feed ingredients in formulated diets for juvenile Penaeus monodon. 

      FP Pascual - 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
      Earthworm and annelids were incorporated in diets for Penaeus monodon juveniles (mean weight 0.54 g) either in wet or dry form. These protein sources were added in amounts needed to replace 10% of the animal source of protein. Other sources of protein in the diet were shrimp head meal, fish meal, and defatted soybean meal. Diets were computed such that two-thirds of total protein came from animal sources and one-third from vegetable sources. Other components of the diet were rice bran, sago palm starch, cod liver oil and a vitamin-mineral mixture. Another diet, used as maintenance diet, served as control. Postlarvae were randomly stocked at 6 individuals/tank in a flowthrough system with 5 replicates/treatment. Each of the oval fiberglass tanks had three 10-cm diameter PVC pipes for shelter. The prawns were fed 10% of biomass twice daily.

      Although treatment means for percent weight gain were not significantly different, the diet that contained dried earthworm or annelid meal gave higher weight gain than diets containing the wet form. The earthworm diet gave higher weight gain than diets containing annelids. Survival rate also followed a similar pattern as that of weight gain. Shrimp fed earthworm (wet or dried) gave survival rates numerically higher than those fed marine annelids. Shrimp fed the control diet had survival rates lower than those fed earthworm-containing diets but higher than those fed the wet annelid diet.

      In another experiment, earthworm or squid was incorporated in the diet. Survival rates of shrimp with earthworm or squid in the diet were significantly higher than those fed the control. Weight gains were not significantly different from each other. Food conversion was generally low. The drawback in the use of earthworm, annelids and squid is that they are relatively expensive compared to fish meal and shrimp head meal.
    • Conference paper

      An ecological approach to mariculture of shrimp: Shrimp ranching fisheries. 

      Y Uno - 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
      Mariculture production in Japan has grown recently to nearly one million tons per year. Mariculture production in the shallow coastal waters of Japan mainly consists of eight species of finfish, six species of shellfish, and three species of algae.

      Kuruma shrimp culture techniques are highly developed. Nevertheless, only 1,800 tons of kuruma shrimp can be produced yearly. There is a demand for this species but culture grounds have become limited and there is not enough space to raise shrimp. In 1980, 600 million postlarvae were produced but one-half had to be released to the sea. The released shrimp that survived and grew have formed a new basis for the "Sea Ranching Fisheries" industry. The trial releases of postlarvae have proven that sea ranching of shrimp can be successful.

      To strengthen the foundation of sea ranching fisheries, there must be future research on ecological impact, as well as on physico-chemical water parameters. The life cycle, feeding habits, and predators of the shrimp must also be studied. Recent releases in Hamana-ko Lagoon, Shizuoka Prefecture, made by the research group of the Hamana-ko Substation of the Shizuoka Prefectural Fisheries Research Station have demonstrated the possibilities of sea ranching. This report discusses the research studies obtained at Hamana-ko Lagoon and the main problems of the use of this sea ranching method in mangrove swamp areas of Southeast Asia.
    • Conference paper

      The ecological aspects of milkfish fry occurrence, particularly in the Philippines 

      S Kumagai - In JV Juario, RP Ferraris & LV Benitez (Eds.), Advances in milkfish biology and culture: Proceedings of the Second International Milkfish Aquaculture Conference, 4-8 October 1983, Iloilo City, Philippines, 1984 - Aquaculture Department, Southeast Asian Fisheries Development Center; International Development Research Centre; Island Publishing House, Inc.
      Aspects of the time, place, and mechanism of occurrence of milkfish (Chanos chanos ) fry, defined as the postlarvae 10-17 mm in total length and 3 weeks of age are considered. Fry occurrence shows seasonal patterns that differ by latitude. In the Philippines (15-21 degree N), fry appear earlier in the south (December-January) and later in the north (March-April); they disappear earlier in the north (July-August) than in the south (December-January). Greater numbers of fry occur in shore waters during the full moon and new moon periods, largely as a consequence of the greater spawning activity during the quarter moon periods. Fry catch by various active and passive filtering gear is greater at floods and high tide than at low and ebb tide. Milkfish fry occur in and are collected mostly from sandy beaches, particularly the surf zone and in and around river mouths. They appear to be distributed mostly near the surface, with greater numbers nearer shore. It appears that larvae smaller than 9-10 mm are distributed in midwaters, but once they reach this size they come up and are carried inshore by tidal and wind-driven currents.
    • Conference paper

      An ecological assessment of seven major lakes in the Philippines 

      MT Zafaralla - In Conservation and Ecological Management of Philippine Lakes in Relation to Fisheries and Aquaculture: Proceedings … Seminar-Workshop held on October 21-23, 1997, INNOTECH, Commonwealth Ave., Diliman, Quezon City, Philippines, 2001 - Aquaculture Department, Southeast Asian Fisheries Development Center; Philippine Council for Aquatic and Marine Research and Development (PCAMRD), Department of Science and Technology; Bureau of Fisheries and Aquatic Resources
      An ecological assessment was done on the seven major lakes in the Philippines, namely; Laguna de Bay, Taal, Naujan, Lanao, Mainit, Buluan, and Bato. The assessment was based largely on secondary data and some primary data. The ecological parameters considered for each lake were focused on published information as well as those unpublished but were made accessible to the author by researchers and agencies of government. The different lakes are classified into three ecological categories, namely; critically degraded, degraded, threatened, and underdeveloped. Where adequate data on a lake is available, emphasis is also given on the examination of the nature of land use, lake development measures, climatic variations in terms of rainfall, and ecological conditions in the lake as they affect fish production. Finally, lake specific and general recommendations are forwarded for management purposes.
    • Article

      Ecological considerations in milkfish farming in marine pens and cages in the Philippines 

      T Bagarinao - UPV Journal of Natural Sciences, 1998 - University of the Philippines in the Visayas
      Milkfish farming in the Philippines has a long history and great importance, being widely regarded as the way to domestic food security. But the industry has faced new challenges in the past decade, with the advent of many other farmed aquatic species, mostly cash crops and "export winners," and with the increased pressure to intensify production in brackishwater ponds and in marine pens and cages. There are no up-to-date government statistics on the area and production of marine pens and cages, but industry insiders estimate a yearly production of about 25,000 mt of sea-grown milkfish in 1996 - 1998, mostly from Pangasinan, but also from Quezon, Davao, Cebu, Bohol, Panay, Samar, and Negros. High yields (2 -38 kg/m3) were made possible by very high stocking rates (3 -75 fingerlings/m3) and feeding rates (2-4 kg feed per kg of fish). The high production costs and the pollution from feed wastes and fish metabolites have stopped most operations within 1 - 2 years. This paper examines the trends and problems in milkfish farming in marine pens and cages, and discusses the ecological limits and the projected ecological footprint of this farming system. Milkfish farming in marine pens and cages, as presently practised, is not the magic solution to the fish deficit in the Philippines and is not an appropriate technology to promote on a wide scale. The required investment is enormous. Properly made pens and cages set up in suitable clean-water locations cost much. The ability of milkfish to ensure domestic food security is negated by the use of fishmeal-based feeds. Fish feeds use up fish meal and other fisheries and agriculture products used by people and other sectors. If marine pens and cages must be promoted, integrated coastal area management, an informed precautionary approach, better infrastructure, and improved feeding management are important to ensure sustainability.
    • Conference paper

      Ecological effects of the use of chemicals in aquaculture. 

      DP Weston - In JR Arthur, CR Lavilla-Pitogo & RP Subasinghe (Eds.), Use of Chemicals in Aquaculture in Asia : Proceedings of the Meeting on the Use of Chemicals in Aquaculture in Asia 20-22 May 1996, Tigbauan, Iloilo, Philippines, 2000 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Many aquaculture chemicals are, by their very nature, biocidal, and may be released to the surrounding environment at toxic concentrations either through misuse, or in some cases, even by following generally accepted procedures for use. Thus, there is a potential for mortality of nontarget organisms. Illustrations are provided of three classes of aquaculture chemicals and their effects on non-target biota: 1) use of a carbaryl pesticide and mortality of non-target invertebrates; 2) use of an organophosphate parasiticide and suspected effects on nearby biota; and 3) effects of antibacterial residues in aquatic sediments on the associated microbial community. Efforts to assess the risks posed by aquaculture chemicals are often frustrated by a lack of information on environmental fate and effects, and data needs to resolve this situation are identified.
    • Conference paper

      The ecological impact of tilapia cage culture in Sampaloc Lake, Philippines 

      AE Santiago - In LM Chou, AD Munro, TJ Lam, TW Chen, LKK Cheong, JK Ding, KK Hooi, HW Khoo, VPE Phang, KF Shim & CH Tan (Eds.), The Third Asian Fisheries Forum. Proceedings of the Third Asian Fisheries Forum, 26-30 October 1992, Singapore, 1994 - Asian Fisheries Society
      Sampaloc lake showed imminent biological death as a consequence of intensive tilapia farming in floating net cages. The progressive disappearance of dissolved oxygen in the entire water column may be an irreversible trend due to continuous feeding. The high amount of BOD5 and the near toxic concentration of total ammonia and total sulphides are ominous signs. Other ecological changes in the lake are the non-appearance of Microcystis bloom, change in phytoplankton composition, number, and species diversity.
    • magazineArticle

      Ecological impacts of coastal aquaculture developments 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1995 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The study presents the type and scale of any ecological change associated with coastal aquaculture development. These are enrichment, interaction with the food web, oxygen consumption, disturbance of wildlife and habitat destruction, interaction between escaped farmed stock and wild species, introduction and transfers, bioactive compounds (including pesticides and antibiotics), chemicals introduced via construction materials, and hormones and growth promoters.
    • Conference paper

      Ecological impacts of seafarming and searanching 

      JL Munro - In F Lacanilao, RM Coloso & GF Quinitio (Eds.), Seminar-Workshop on Aquaculture Development in Southeast Asia and Prospects for Seafarming and Searanching; 19-23 August 1991; Iloilo City, Philippines., 1994 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Seafarming has ecological effects such as pollution and eutrophication of adjacent areas by excess food or by feces or modification of habitats by physical structures. More subtle effects on the communities result from heavy consumption of plankton or benthos by caged or enclosed farmed organisms and consequent reduction of availability of food to adjacent natural communities. Seapens, in which monocultures are reared, develop a radically different benthos from that in adjacent areas. Seafarms can become focal points from which pathogens and parasites can be spread.Searanching, in which stocks are enhanced by the addition of hatchery-reared recruits, has the potential to cause significant changes in the composition and stability of marine communities. Enhanced recruitment of a species will have negative effects on both its prey and its competitors but will enhance the biomass of its predators.Enhanced recruitment of a stock of apex predators will decrease the biomass of its prey and cause changes in the composition of the community. The effects of searanching are amenable to modelling, and the likely effects of proposed searanching schemes should be examined before these are implemented.The magnitude of the effects of searanching will depend on the degree to which the area is naturally saturated with recruits of that species and on the rate of exploitation. Poor management of the stock, resulting in under- or over-exploitation, will have highly destabilizing effects on the communities.Seafarming or searanching can have negative effects on the gene pools of natural stocks and result in changes in life histories or in behavior.
    • magazineArticle

      Ecological limits of high-density milkfish farming 

      T Bagarinao - SEAFDEC Asian Aquaculture, 1997 - Aquaculture Department, Southeast Asian Fisheries Development Center
      In the Philippines at present, milkfish farming in ponds includes a wide range of intensities, systems and practices. To make aquaculture possible, ecosystems are used as sources of energy and resources and as sinks for wastes. The growth of aquaculture is limited by the life-support functions of the ecosystem, and sustainability depends on matching the farming techniques with the processes and functions of the ecosystems, for example, by recycling some degraded resources. The fish farm has many interactions with the external environment. Serious environmental problems may be avoided if high-intensity farms are properly planned in the first place, at the farm level and at the level of the coastal zone where it can be integrated with other uses by other sectors. It is believed that the key to immediate success in the mass production of milkfish for local consumption and for export of value-added forms may be in semi-intensive farming at target yields of 3 tons per ha per year, double the current national average. Intensive milkfish farming will be limited by environmental, resource and market constraints. Integrated intensive farming systems are the appropriate long-term response to the triple needs of the next century: more food, more income, and more jobs for more people, all from less land, less resources, and less non-renewable energy.
    • Article

      Ecological role and services of tropical mangrove ecosystems: a reassessment 

      Aim

      To reassess the capacity of mangroves for ecosystem services in the light of recent data.

      Location

      Global mangrove ecosystems.

      Methods

      We review four long-standing roles of mangroves: (1) carbon dynamics – export or sink; (2) nursery role; (3) shoreline protection; (4) land-building capacity. The origins of pertinent hypotheses, current understanding and gaps in our knowledge are highlighted with reference to biogeographic, geographic and socio-economic influences.

      Results

      The role of mangroves as C sinks needs to be evaluated for a wide range of biogeographic regions and forest conditions. Mangrove C assimilation may be under-estimated because of flawed methodology and scanty data on key components of C dynamics. Peri-urban mangroves may be manipulated to provide local offsets for C emission. The nursery function of mangroves is not ubiquitous but varies with spatio-temporal accessibility. Connectivity and complementarity of mangroves and adjacent habitats enhance their nursery function through trophic relay and ontogenetic migrations. The effectiveness of mangroves for coastal protection depends on factors at landscape/geomorphic to community scales and local/species scales. Shifts in species due to climate change, forest degradation and loss of habitat connectivity may reduce the protective capacity of mangroves. Early views of mangroves as land builders (especially lateral expansion) were questionable. Evidence now indicates that mangroves, once established, directly influence vertical land development by enhancing sedimentation and/or by direct organic contributions to soil volume (peat formation) in some settings.

      Main conclusions

      Knowledge of thresholds, spatio-temporal scaling and variability due to geographic, biogeographic and socio-economic settings will improve the management of mangrove ecosystem services. Many drivers respond to global trends in climate change and local changes such as urbanization. While mangroves have traditionally been managed for subsistence, future governance models must involve partnerships between local custodians of mangroves and offsite beneficiaries of the services.
    • Book

      Ecology and farming of milkfish 

      T Bagarinao - 1999 - Aquaculture Department, Southeast Asian Fisheries Development Center
      This book is a reader-friendly illustrated account of the life history of milkfish (Chanos chanos) in nature and in aquaculture. It describes the different farming systems and status of the milkfish industry, and recommends means to ensure sustainability.