Now showing items 1-11 of 11

    • Book

      Breeding and seed production of the giant freshwater prawn (Macrobrachium rosenbergii) 

      MLA Cuvin-Aralar, MA Laron, EV Aralar & UC de la Paz - 2011 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 52
      An extension manual describing biology, broodstock management, hatchery and nursery operations, feeding management, packing and transport, and health management of the giant freshwater prawn.
    • Book

      Cage culture of the giant freshwater prawn (Macrobrachium rosenbergii) 

      ML Cuvin-Aralar, EV Aralar & AG Lazartigue - 2011 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 50
      An extension manual describing biology, site requirement, grow-out operations, health management, harvest, post harvest handling and processing, and economic analysis.
    • Article

      Cage culture of the Pacific white shrimp Litopenaeus vannamei (Boone, 1931) at different stocking densities in a shallow eutrophic lake 

      MLA Cuvin-Aralar, AG Lazartigue & EV Aralar - Aquaculture Research, 2009 - Blackwell Publishing
      Postlarvae of Litopenaeus vannamei were acclimated and stocked in lake-based cages at the following stocking densities: 10, 20, 30 and 40 shrimp m−2. Another set of shrimp was stocked in concrete tanks as reference samples at 30 shrimp m−2. Significant differences were observed among stocking densities throughout the 95-day culture. The final weight at harvest decreased with increasing stocking density: mean weights of 23.3, 15.8, 13.0, 10.9 and 14.6 g for the 10, 20, 30, 40 shrimp m−2 and reference tanks were observed respectively. There were no significant differences in survival throughout the culture period, ranging between 69% and 77%. Daily growth rates (range: 0.11–0.24 g day−1) and specific growth rates (range: 3.54–4.34%) also differed significantly among stocking densities, both increasing with decreasing stocking density. The feed conversion ratio in the cages did not differ among the stocking densities, ranging from 1.53 to 1.65. The relationship between stocking density and mean individual weight at harvest followed the equation y=81.06x−0.54 (R2=0.938) and that of stocking density and production (in g m−2) is y=58.01x−0.46 (R2=0.834).
    • Article

      Culture of Macrobrachium rosenbergii (De Man 1879) in experimental cages in a freshwater eutrophic lake at different stocking densities 

      ML Cuvin-Aralar, EV Aralar, MA Laron & W Rosario - Aquaculture Research, 2007 - Blackwell Publishing
      Macrobrachium rosenbergii (de Man 1879) juveniles (0.4 g) were cultured in experimental cages (L × W × H: 2.5 × 1 × 1 m) in Laguna de Bay, the largest lake in the Philippines. The following stocking densities at four replicates each were used: 15, 30, 60 and 90 prawns m−2 of cage bottom. The mean sizes at harvest after 5 months of culture ranged from 14.3 g for the highest stocking density to 26.3 g for the lowest. The mean size at harvest, daily growth rate and size class distribution were significantly influenced by stocking density, with those at the lowest stocking density showing significantly better growth and overall proportion of larger prawns. Heterogeneous individual growth (HIG) was fairly evident in all treatments. The percentage of blue-clawed males was not influenced by treatment but the mean weight was significantly higher in the lower stocking densities. Both the percentage and mean weight of berried females were significantly higher in the lowest stocking density. Survival was the highest in the lower stocking densities (55.3%, 54.0%, 52.7% and 36.9% for 15, 30, 60 and 90 prawns m−2 respectively). Feed conversion ratio (FCR) improved with decreasing stocking density, ranging from 2.1 to 3. As expected, yield per cropping increased with stocking density and ranged from 450 to 1089 g m−2 yr−1 of actual cage area. Production values obtained in the cage cultured M. rosenbergii were comparable to or even higher than those reported from pond culture, given that the stocking densities used in this study were generally higher than in ponds. The results show that the farming of M. rosenbergii in cages in lakes is a viable alternative to pond culture and has the potential of improve aquaculture production in lakeshore fish farming communities.
    • Article

      Effects of long-term exposure to a mixture of cadmium, zinc, and inorganic mercury on two strains of tilapia Oreochromis niloticus (L.) 

      MLA Cuvin-Aralar & EV Aralar - Bulletin of Environmental Contamination and Toxicology, 1993 - Springer Verlag
      Tilapia are an economically important group of fish. They have a short generation period of 3-6 months, and exhibit successive breeding. In addition, their fast growth, herbivorous or omnivorous feeding habits, high food conversion efficiency, ease of spawning, ease of handling, resistance to disease and good consumer acceptance make this group of fish highly popular in aquaculture in Asia, Africa and other developing countries. Tilapia have been the subject of research on pollution effects over the last decade. The purpose of this study was to determine growth, accumulation and depuration responses of 2 strains of the Nile tilapia, Oreochromis niloticus, chronically exposed to a mixture of heavy metals including cadmium, zinc and mercury.
    • Article

      Effects of low nitrogen-phosphorus ratios in the phytoplankton community in Laguna de Bay, a shallow eutrophic lake in the Philippines 

      ML Cuvin-Aralar, U Focken, K Becker & EV Aralar - Aquatic Ecology, 2004 - Springer Verlag
      The effects of low nitrogen-phosphorus ratios on microalgae from a large eutrophic freshwater lake in the Philippines were investigated. Natural microalgal populations from Laguna de Bay, the largest lake in the Philippines, were cultured using three different nitrogen-phosphorus weight ratios (2N:1P; 6N:1P and 12N:1P) at two phosphorus concentrations (0.25 and 0.5 mg l–1) in each case. The growth and genera composition of the cultures under the different treatments were followed for a 12-week period. Community level responses were assessed based on species richness (s), Shannon-Wiener Index (H’), Simpson Index (λ) and Evenness (J’). Among the different microalgal groups, only the chlorophytes showed a significantly higher density in response to the 12N:1P treatment at the higher P concentration, indicating that the nutrient ratio had a significant interaction with the nutrient levels used in the experiments. The genera found in the different treatments were generally similar; however, the degree of dominance of some varied with treatment during the experiment. The succession of dominant genera also differed among the N:P treatments. The diatoms like Fragilaria, Aulacoseira (= Melosira) and Nitzschia dominated the lowest N:P. On the other hand, chlorophytes (Kirchneriella and Scenedesmus) dominated the highest N:P treatment, particularly from the second to the seventh week of the experiments with the diatoms becoming co-dominant only towards the eighth week until the end of the experimental. The 6N:1P treatment showed a mixed dominance between the diatoms and the chlorophyte genera. The various indices of diversity indicate significantly lower diversity only in the 12N:1P at 0.5 mg l–1 P and not in 12N:1P at 0.25 mg l–1 P.
    • Book

      Induced breeding and seed production of bighead carp Aristichthys nobilis (Richardson) 

      AC Gonzal, CB Santiago, AC Fermin & EV Aralar - 2001 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 33
      A 40-page manual that details the advanced induced spawning technology for Bighead carp developed at SEAFDEC/AQD through the years. This handbook emphasizes the adoption of efficient carp hatchery techniques for optimal production of good quality eggs and juveniles.
    • magazineArticle

      Meeting social and economic challenges in Southeast Asian aquaculture: Targeting rural aquaculture development for poverty alleviation 

      ND Salayo, DB Baticados, EV Aralar & BO Acosta - Fish for the People, 2012 - SEAFDEC Secretariat
      In 2010, five Southeast Asian countries led by Vietnam and followed by Indonesia, Thailand, Myanmar, and the Philippines, have successfully joined the ranks of the world’s top 10 producers of food fish from aquaculture. Taking into account aquaculture production in general which includes seaweeds, the region’s production from aquaculture had contributed more than 45% to the region’s total fishery production, about 24% to the world’s production from aquaculture, and about 10% to the world’s total fishery production in 2010. As shown in the statistics reports, most of the aforementioned countries recorded double-digit growth rates in aquaculture production from 2006 to 2010, ranging from 18 to 62 percent. Another milestone in the fisheries sector of the region is the engagement of about 11 million people in aquaculture and its ancillary industries. In spite of these figures, the region’s rural areas where aquaculture development is taking giant strides remain the most impoverished groups in most countries of Southeast Asia. In an attempt to address this concern, SEAFDEC Aquaculture Department compiled the results of the implementation of its program on Meeting Social and Economic Challenges in Aquaculture which had been tried in local setting in the Philippines, with the objective of developing aquaculture technology adoption pathways that could be promoted in the other Southeast Asian countries with the same conditions as those in study sites in the Philippines, as means of alleviating poverty in rural areas.
    • Article

      Microcystins in natural blooms and laboratory cultured Microcystis aeruginosa from Laguna de Bay, Philippines. 

      ML Cuvin-Aralar, J Fastner, U Focken, K Becker & EV Aralar - Systematic and Applied Microbiology, 2002 - Urban & Fischer Verlag
      Laguna de Bay, the largest freshwater lake in the Philippines, experiences periodic blooms of the cyanobacteria Microcystis aeruginosa. Blooms of these cyanobacteria in 1996, 1998 and 1999 were sampled. HPLC and MALDI-TOF mass spectrometry were used to analyze for microcystins. A total of 16 structural variants of the toxin were isolated from the samples with microcystin LR (MC-LR) as the most abundant variant in the samples from 1996 and 1999 making up 77 to 85% of the total, respectively. MC-RR was the dominant variant in the 1998 bloom making up 38%. The samples from 1996 had the highest total toxin concentration (4049 µg g-1) followed by those from 1998 (1577 µg g-1) and 1999 (649 µg g-1). A strain of M. aeruginosa previously isolated from the lake was also cultured in the laboratory under different nitrogen concentrations (1, 3 and 6 mg L-1) and elevated phosphorus concentration (0.5 mg L-1) to determine the influence of these factors on toxin production. A total of 9 different structural variants of microcystin were isolated from the laboratory cultures with MC-LR consisting more than 75% of the total in all treatments. No significant differences in the total toxin concentration as well as the % distribution of the different variants among treatments were observed. However, the strain of M. aeruginosa cultured in the laboratory had from 3 to 20 times higher total microcystin than those harvested from the lake.
    • Article

      Net mesh size affects production of giant freshwater prawn Macrobrachium rosenbergii cultured in lake-based cages 

      MLA Cuvin-Aralar, AG Lazartigue & EV Aralar - Journal of Applied Ichthyology, 2013 - Wiley
      Cage culture of freshwater prawns in open waters is prone to the entry of predators and competitors that particularly hamper production. This study was conducted to determine how smaller net mesh sizes to reduce entry of unwanted species inside the cages affects the production of Macrobrachium rosenbergii in lake-based cages. Juvenile prawns were stocked in cages (7 × 7 × 1.5 m) of two net mesh sizes at 10 individuals m-2 and cultured for 10 months in a shallow eutrophic lake in the Philippines. The two net mesh sizes were either 5 mm-mesh B-nets or and 1 mm-mesh Hapa nets. Each treatment had four replicates each and was fed based on biomass with commercially formulated feed. Monitoring of various production parameters was done during the two phases of culture: batch phase on days 63 and 127 and the selective harvest phase on days 187, 219, 253, 281 and 313, when the experiment was terminated. For the first 127 days of culture, the weight, percent weight increase, daily growth rate (DGR), specific growth rate (SGR), yield and feed conversion ratio (FCR) were significantly better in prawns reared in the Hapa compared to the B-nets. During the selective harvest phase the blue claw, orange claw and berried females were selectively harvested and the remaining prawns returned to the cages. After changes in stocking density through culling, ancova was used to compare the effect of mesh size with the total number of prawns returned to the cages as a covariate. Yield was significantly higher in the Hapa nets. Weight, DGR, SGR and FCR were also consistently higher in the Hapa nets, although not always significantly different. The overall better performance of prawns reared in the Hapa net cages was due to: (i) the reduction in the entry of predator and competitor species in the finer-meshed Hapa compared to the larger mesh B-net, (ii) more natural food trapped inside the Hapa cages, and (iii) a higher number of selectively harvested prawns, which decreased stocking density in the cages and improved growth. Use of small mesh size nets is recommended in the cage culture of M. rosenbergii in inland natural water bodies.
    • Article

      Resistance to a heavy metal mixture in Oreochromis niloticus progenies from parents chronically exposed to the same metals 

      MLA Cuvin-Aralar & EV Aralar - Chemosphere, 1995 - Elsevier
      Adult Oreochromis niloticus were mass spawned in concrete tanks. The one-month old progenies (F1) were exposed for two months to a mixture of 0.01 mg L−1 Hg, 0.1 mg L−1 Cd and 1.0 mg L−1 Zn. The survivors were grown to sexual maturity in a natural environment (lake). The fish were spawned and the progenies (F2) of the exposed F1 (EF1) were exposed to another mixture of the three metals: 3.0 mg L−1 Zn, 0.30 mg L−1 Cd and 0.01 mg L−1 Hg, both in a static and static-renewal system. Another group of F2 from unexposed F1 (UF1) received the same treatment. Results showed that in both exposure systems, survival of the F2 of EF1 was significantly higher (P<0.05) than those from UF1. The medial lethal time (LT50) of the F2's were estimated from the time-response curve following regression analysis: 5.16 days (F2 of UF1) and 9.03 days (F2 of EF1) in the static exposure experiment; 3.34 days (F2 of UF1) and 5.52 days (F2 of EF1) in the static-renewal run. Exposure of the parental stock resulted in the culling out of individuals which were more susceptible to the heavy metals. The more resistant members of the population (survivors) which have the ability to adapt to the toxicants were able to pass on the resistance to their offspring. The results are supported by other studies in the field which demonstrate high resistance in populations of organisms living in contaminated sites.