Now showing items 1-20 of 22

    • Article

      Agar yield and gel strength of Gracilaria heteroclada collected from Iloilo, Central Philippines 

      MRJ Luhan - Botanica Marina, 1992 - Walter de Gruyter
      Seasonality of yield and gel strength of agar from Gracilaria heteroclada was determined. Gel strength was high (510-794 gm cm-2) during early dry season (October-March) and low (43-101 gm cm-2) during the wet season (May-August). A negative correlation exist (P ≤ 0.05) between agar yield and gel-strength.
    • Article

      Biomass yield of Isochrysis galbana (Parke; clone T-ISO) and growth of Brachionus rotundiformis (Tschugunoff) using continuous cultivation method 

      MR de la Peña - Philippine Agricultural Scientist, 2014 - College of Agriculture, University of the Philippines Los Baños
      Batch culture of Isochrysis galbana clone T-ISO is difficult due to its unstable biomass production; hence, the effect of continuous cultivation at different dilution rates was investigated to compare its productivity with that of batch culture. Significantly higher total algal cell yield was attained in continuous cultures (1.70 × 108 and 1.03 × 108 cells L-1 at 0.60 d-1 and 0.30 d-1 dilution rates, respectively) compared with batch culture (0.16 × 108 cells L-1); the batch culture did not receive any inflow of nutrients. The amount of protein per cell was similar in both batch and continuous cultures at 0.60 d-1 dilution rate after 24 h and 5 d in both culture systems. Chlorophyll a yield was not affected by dilution rate but decreased as the culture aged. The dry weight yield was also similar in both batch and continuous cultures. The higher nitrate concentration supplemented in the batch culture resulted in higher cell density and elevated protein content of the alga. Rotifer (Brahionus rotundiformis) cultures that received inflow of nutrients from the algal tanks had significantly higher (P<0.05) peak population count (28 and 33 individuals mL-1 at 0.30 and 0.60 d-1 dilution rates, respectively) compared with rotifer cultures that did not receive an inflow of food (18.22 individuals mL-1). The higher biomass yield of T-ISO using continuous cultivation method can increase the population growth of rotifer under tropical conditions.
    • Article

      Culture and economics of wild grouper (Epinephelus coioides) using three feed types in ponds 

      I Bombeo-Tuburan, EB Coniza, EM Rodriguez & RF Agbayani - Aquaculture, 2001 - Elsevier
      The performance of wild Epinephelus coioides juveniles was compared by feeding with live tilapia juveniles, fish by-catch, and formulated diet for 5 months in grow-out ponds. To minimize cannibalism, the groupers were graded into small (BW=24.9±7.3 g), medium (45.8±5.7 g), and large (84.1±30.0 g) size groups as block in a Randomized Complete Block Design (RCBD) and reared in nine 350-m2 ponds. To supply the tilapia juveniles, adult tilapia were grown 2 months prior to stocking of grouper at a rate of 15 tilapia/grouper. Grouper fed by-catch were significantly higher (P<0.01) than the other treatments in terms of final length and total production. The quality of by-catch could be gleaned by its efficient feed conversion ratio (FCR) of 1.0 (dry basis), significantly better (P<0.01) than the formulated diet that had an FCR of 2.8. Using by-catch, 47% of the harvest weighed >400 g and only 14% was classified <200 g. The cost of juvenile grouper and feeds represented 88–89% of the total investment in all treatments. Economic sensitivity analysis showed that a combination of improvement in factors such as price of grouper juveniles, feeds, yield, survival, and FCR would result in higher return-on-investment (ROI). When cost and returns were considered, feeding juveniles with by-catch was more profitable because it resulted in net income of Php 361,623/ha/year, an ROI of 155%, and a payback period of 0.4 year. The results clearly show that these economic indicators appear to be attractive, thus making grouper pond culture using by-catch a viable industry. More research efforts should, however, be directed towards developing a cost-effective formulated diet for the grow-out culture of E. coioides.
    • Article

      The effect of stunting on growth, survival, and net production of milkfish (Chanos chanos Forsskal) 

      I Bombeo-Tuburan - Aquaculture, 1988 - Elsevier
      The seasonal abundance of milkfish fry in the Philippines has led to the practice of buying a sufficient supply during the peak season to compensate for the shortage during slack periods. Fry that are not immediately grown out are crowded and stunted in transition ponds until they are transferred to rearing ponds. Milkfish farmers believe that stunted fingerlings grow faster than newly grown ones and therefore yield extra croppings. To assess the efficiency of production schemes, stunted and non-stunted milkfish fingerlings were cultured in twelve 144-m2 ponds for a 3-month period. The treatments employed were: Treatment I, 2-month-old fingerlings; Treatment II, 3-month-old fingerlings; and Treatment III, 6-month-old fingerlings, with the initial weights of 3.3 g, 7.8 g, and 43.1 g, respectively. Survival, netproduction, cumulative and monthly weight gains did not differ significantly (P > 0.05) among the three treatments. The results indicate that stunting did not illicit a significant increase, nor did it adversely affect the growth, survival, and netproduction of milkfish in a straight culture system. Stunting can therefore be practised by farmers to provide an adequate supply of fingerlings for year-round operation.
    • Article

      Evaluation of agar from three species of Gracilaria from Panay and Guimaras islands 

      TR de Castro - The Philippine Scientist, 1993 - San Carlos Publications, University of San Carlos
      Agar from three species of Gracilaria, G. changii G. coronopifolia, and Gracilariopsis heteroclada, collected form Panay and Guimaras islands was evaluated. Each species was pretreated with NaOH solution before extraction. Highest agar yields were obtained following alkaline pretreatment at the lowest concentration (1% NaOH) for all species. Highest gel strengths were obtained at different alkaline pretreatment conditions: 644 ± 3.4 g cm-2 at 3 % NaOH for 60 min for G. changii, 641 ± 11.9 g cm-2 at 5 % NaOH for 30 min for G. heteroclada, and 170 g cm-2 at 5 % NaOH for 30 min G. coronopifolia. Agar gelling temperatures ranged from 38.5-40ºC and agar melting temperature ranged from 80.5-85 ºC. Specific viscosity was highest for agar from G. changii at 18 cps. Moisture and ash contents ranged from 8.04-15.20 % and 4.32-4.98%, respectively. Based on the result for this study, G. heteroclada and G. changii are two species which merit further studies for their prospective commercial value to the different industries using agar.
    • Article

      Evaluation of plant proteins as partial replacement for animal proteins in diets for Penaeus indicus and P. merguiensis juveniles 

      VD Peñaflorida - The Israeli Journal of Aquaculture-Bamidgeh, 2002 - Society of Israeli Aquaculture and Marine Biotechnology
      The growth rate and survival of two white shrimps, Penaeus indicus and P. merguiensis, fed diets in which fishmeal was partially replaced with plant protein sources were investigated in three trials. In trial 1 with P. indicus, soybean, yeast and leaf meals of kangkong, papaya and Cassia tora L. were screened as partial substitutes for fishmeal. The total biomass of shrimp fed 20% yeast (20yeast) was highest but not significantly different than that of shrimp fed 10yeast and 10papaya. Survival was highest with 20yeast, 10papaya and 10yeast. Shrimp fed Cassia tora L. had the highest weight gain and SGR but their survival was similar to those fed poor performing diets. In trial 2 with P. merguiensis, the ingredients were modified by decreasing fishmeal and increasing the yeast and soybean substitution. The biomass of the shrimp fed 10 yeast was similar to that of the shrimp fed 20yeast and 26 soybean, the weight gain and SGR were similar to shrimp fed 20yeast while survival was highest but not different from 20yeast and 26 soybean. In trial 3 with P. indicus, weight gain and SGR were best with 20yeast and 34soybean. However, biomass and survival did not differ among replacement levels.

      The performance of the white shrimp varied with different levels of yeast and soybean meal incorporation. The response of P. indicus was best with 20yeast (15% by weight) or 34soybean meal (34% by weight) while that of P. merguiensis was with 10yeast (7% by weight), 20yeast (15% by weight) or 26soybean meal (26% by weight). Partial replacement of fishmeal with yeast or soybean meal would result in lower feed costs but the use of these feeds needs further refinement since survival was low in all treatments. Rearing techniques, such as increasing the feeding frequency, simulating deep pond conditions or using adequate substrates, should be refined.
    • 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

      Growth and survival of Penaeus monodon juveniles fed a diet lacking vitamin supplements in a modified extensive culture system 

      AT Triño, VD Peñaflorida & EC Bolivar - Aquaculture, 1992 - Elsevier
      Penaeus monodon juveniles with mean initial weight from 0.11 to 0.17 g were fed diets with and without vitamin supplement. The diets contained 34% protein and 8% fat. The animals were stocked at 5/m2 in 320-m2 earthen ponds and reared for 135 days. Growth, survival, net production, and net cost of production per kg of P. monodon were not significantly affected even if supplemental vitamins were eliminated from the diet. The absence of extra vitamins from the diet may have been compensated either by the basal diet used or by ingestion of natural food existing in the ponds. In either case, the possible influence of vitamins from these sources is manifested in the overall effects on growth, survival and net production of prawns when no vitamin supplement is added to the diet. Results obtained showed that the difference between diets in cost of production was statistically not significant (P > 0.05). However, the favorable cost difference of P 18.02 per kg of prawns produced would make it more profitable to use the diet without vitamin supplement in a modified extensive culture system.
    • Article

      Growth and yield of Asian catfish Clarias macrocephalus (Gunther) fed different grow-out diets 

      EB Coniza, MR Catacutan & JD Tan-Fermin - The Israeli Journal of Aquaculture-Bamidgeh, 2003 - The Society of Israeli Aquaculture and Marine Biotechnology (SIAMB)
      Juveniles of the Asian catfish Clarias macrocephalus (3.6±0.17 g; 78.0±0.09 mm) were fed one of four diets: a laboratory-formulated diet of 18.9% (Diet 1) or 34.2% (Diet 2) protein, a com- mercial feed pellet of 28.9% protein (Diet 3) or a diet of 80% blanched chicken entrails and 20% rice bran (31.7% protein; Diet 4). After 120 days of culture, catfish fed Diet 2 grew significantly better (p<0.05) than the other groups, reaching 108.9 g and 232.8 mm (daily weight gain 0.88 g; specific growth rate 2.9%), with a condition factor of 0.86 and production of 18.2 kg per 25 m2 pen. Feed conversion with Diets 2 and 3 (2.5 and 2.3, respectively) was better than with Diets 1 and 4 (3.4 and 5.0). Survival (68-81%) did not differ significantly among treatments (p>0.05). Catfish fed Diet 2 had the highest apparent lipid retention (131.7%). The protein efficiency ratio was lowest (1.3) in Diet 2, but did not differ significantly from Diets 1 and 3. Catfish fed Diet 4 were fatty and had a lower crude protein content. Results suggest that C. macrocephalus fed 34.2% crude protein have a significantly higher weight and total yield. Further, a taste test showed that odor, flavor and appearance did not differ amongst the diets.
    • Article

      Growth rate, yield and economics of Gracilariopsis bailinae (Gracilariales, Rhodophyta) using fixed bottom long-line method 

      AQ Hurtado-Ponce, RF Agbayani & GP Samonte-Tan - Philippine Journal of Science, 1997 - Science and Technology Information Institute
      Vegetative thalli of Gracilariopsis bailinae weighing 10 g each were tied to a 5-m monofilament line with plastic strips and laid horizontally on the substrate and were observed to grow at 30 d interval for 9 months. The monthly growth rate and yield were determined and a cost and return analysis of the culture system was made. The monthly growth rate of the seaweed was significantly different (P=0.05) over culture month. The highest average growth rate was 6.7 percent/day while the lowest was 1.7 percent. The lowest and highest average yield (dry wt) was 72 g and 660 g m-2 mo-1, respectively.

      A capital asset of P1,680, working capital of P2,980, and annual production cost of P5,860 were calculated from the culture system. An annual net returns of P31,292 was computed based on a 1,000 m2 area. Return on investment is 671.50 percent while payback period is 1.7 months.
    • 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

      Influence of stocking density and fertilization regime on growth, survival and gross production of Penaeus monodon Fabricius in brackishwater ponds 

      PF Subosa & MN Bautista - The Israeli Journal of Aquaculture-Bamidgeh, 1991 - Society of Israeli Aquaculture and Marine Biotechnology
      Twelve 0.1 ha earthen ponds were stocked at 3,500 or 7,000/ha with 1-month old nursery reared Penaeus monodon Fabricius (1.73 g). Fertilizer treatments were 125 kg chicken manure plus 4.1 kg diammonium phosphate (18-46-0) and 6.56 kg urea (45-0-0) per application for treatments U3500 and U7000 and 125 kg chicken manure plus 8.15 kg diammonium phosphate and 0.89 kg urea per application for treatments P3500 and P7000. Fertilizers were broadcast 10 days after pest eradication and every two weeks thereafter. Water was exchanged (20%) one day before fertilization throughout the 86-day culture period. Shrimp yields at harvest were: P7000, 193.6 kg/ha; P3500, 119.4 kg/ha; U3500, 97.5 kg/ha; and U7000, 82.4 kg/ha. Mean survival for each treatment was 96.2%, 97%, 89.3% and 75%, respectively. There were significant differences in shrimp yields at harvest among treatments (p < 0.05).
    • Article

      The interactive effect of some environmental factors on the growth, agar yield and quality of Gracilariopsis bailinae (Zhang et Xia) cultured in tanks 

      AQ Hurtado-Ponce & HB Pondevida - Botanica Marina, 1997 - Walter de Gruyter
      The single and interactive effects of light and temperature, salinity, and urea enrichment on the growth and agar yield and quality of Gracilariopsis bailinae were determined under indoor and outdoor tank conditions. Culture period was 6 weeks. Growth rate reached its peak on the second week in all culture conditions and gradually decreased towards the end of the culture period. Higher growth rates were obtained in seaweed cultured in outdoor (0.27-1.12% day-1) than in indoor (0.21-0.72% day-1) tanks; with urea enrichment and lower salinity levels (15-25ppt). A significant interactive effect was demonstrated between and among the environmental parameters on the growth of the seaweed. Highest gel strength (870 g cm-1) and lowest sulfate content (3.1 µg mg-1) were obtained at 25ppt, without urea enrichment and in indoor tanks. A significant interactive effect of light intensity and temperature-urea enrichment was ascertained on agar yield; also of light intensity and temperature-salinity on gel strength and sulfate content. Positive and negative correlation was likewise established between agar properties.
    • Article

      Low or partial discharge and closed-recirculating systems for the culture of shrimp [Penaeus monodon (Fabricius)] at several demonstration sites in the Philippines 

      DD Baliao & MA de los Santos - The Philippine Agricultural Scientist, 2011 - College of Agriculture, University of the Philippines Los Baños
      A series of verification runs on the farming of shrimp [Penaeus monodon (Fabricius)] using environment-friendly techniques was conducted in different pilot demonstration sites including privately owned farms in the Philippines from 2001 to 2005. Encouraging results were achieved using the low or partial discharge and closed-recirculating systems following the advanced environment-friendly protocols. In the low or partial discharge system, 11 grow-out ponds were stocked with P. monodon post larvae (PL) at densities between 15 and 25 m-2 while in the closedrecirculating system, eight grow-out ponds were stocked with PLs at densities between 30 and 60 m-2. Both systems incorporated the use of head and tail reservoirs, crop rotation, filter box, salinity reduction, long-arm paddlewheel aerators, biomanipulators, biofilters, sludge collectors and quality feeds.

      In the low or partial discharge system, an average total yield of 5.3 ± 0.8 tons ha-1, a feed conversion ratio (FCR) of 1.4 ± 0.3 and a survival rate of 86 ± 12 % were achieved after 109–159 d of culture (DOC). In a closed recirculating system, however, an average total yield of 8.3 ± 4.0 tons ha-1, FCR of 1.9 ± 0.2 and survival rate of 76 ± 15 % were achieved after 126–150 DOC.

      Analyses of effluents from grow-out ponds revealed that treatment using the tail reservoir with installed baffles and oysters (Crossostrea sp.) and seaweed (Gracilaria sp.) used as biofilters effectively reduced the dissolved organic nutrient concentration to optimum levels before the water was recycled or released to the surrounding body of water. Shrimps were observed to be growing and feeding normally, with no signs of bioluminescence at night, and no sluggish swimming behavior.
    • Article

      Nitrogen and phosphorus utilization in the cyanobacterium Microcystis aeruginosa isolated from Laguna de Bay, Philippines 

      SF Baldia, AD Evangelista, EV Aralar & AE Santiago - Journal of Applied Phycology, 2007 - Springer Verlag
      Phytoplankton supports fisheries and aquaculture production. Its vital role as food for aquatic animals, like mollusks, shrimp, and fish cannot be overemphasized. Because of its contribution as a food source for fish, the growth kinetics of Microcystis aeruginosa, a dominant cyanobacterium in the lake, was studied. The regular occurrence of M. aeruginosa is experienced during the months of May to July or from September to November in Laguna de Bay, the largest freshwater lake in the Philippines. M. aeruginosa was collected from Laguna de Bay, isolated, and established in axenic conditions. Data on the growth kinetic parameters for nitrate-nitrogen and phosphate-phosphorus utilization by M. aeruginosa gave the following values: half-saturation constant (Ks), 0.530 mg N. L−1 and 0.024 mg P. L−1 respectively; maximum growth rate (μmax), 0.671. d−1 and 0.668. d−1 respectively; maximum cell yield, 6.5 and 6.54 log, cells. ml−1 respectively; nutrient level for saturated growth yield, 8.71 mg N. L−1 and 0.22 mg P. L−1 respectively; and minimum cell quota (Q0), 2.82 pg N. cell−1 and 0.064 pg P. cell−1 respectively. The low Ks value and high maximum growth rate (μmax) for phosphorus by M. aeruginosa would suggest a high efficiency of phosphorus utilization. On the other hand, the high Ks value for nitrogen indicated a low rate of uptake for this nutrient.
    • Article

      Partial replacement of fishmeal by defatted soybean meal in formulated diets for the mangrove red snapper, Lutjanus argentimaculatus (Forsskal 1775) 

      MR Catacutan & GE Pagador - Aquaculture Research, 2004 - Blackwell Publishing
      This study was conducted to evaluate the effect on growth and feed efficiencies of the mangrove red snapper (Lutjanus argentimaculatus) when dietary fishmeal is partially replaced by defatted soybean meal (DSM). In the preliminary experiment, snapper (mean weight±SD, 58.22±5.28 g) were fed in triplicate with different dietary amounts of DSM (7.8–42.2%) that were formulated to be isonitrogenous and isocaloric. After 14 weeks, survival, growth and feed efficiencies, and hepatosomatic index (HSI) did not differ. Based on these results, a feeding trial was done using a positive control diet that contained 64% fishmeal, while the other four diets had DSM levels of 12%, 24%, 36%, and 48% that replaced fishmeal protein at 12.5%, 25%, 37.5%, and 50% respectively. All diets were formulated to have about the same protein level (50%), protein to energy ratio (P/E of 25-mg protein kJ−1), and dietary energy (19.8 MJ kg−1). These were fed to triplicate groups of snapper (mean total weight tank−1±SD, 73.19±1.2 g) at 15 fish (average weight, 4.88 g) per 1.5-t tank for 19 weeks. Growth (final average weight and specific growth rate (SGR), feed conversion ratio (FCR), survival, and HSI were not significantly different (P>0.05) while protein efficiency ratios or PERs were similar in treatments with DSM. Among snapper fed DSM, haematocrit value was significantly lower in fish fed 48% DSM and not different with fish fed 36% DSM. Whole-body crude fat of snapper fed 48% DSM was lowest while the crude protein and nitrogen-free extract (NFE) levels were highest. Histopathological analysis showed that lipid vacuoles in livers of snapper were reduced in size as dietary DSM increased. There was slight lipid deposition in the liver of snapper at 36% DSM while at 48% DSM it was excessive and hepatocytes were necrotic. There were no differences in the histology of snapper intestine. Under the experimental condition of this study, DSM can be used in snapper diets at 24% (replacing 25% of fishmeal protein) based on growth, survival and feed efficiencies, and histology of liver and intestine. For a lesser diet cost, an inclusion level higher than 24% DSM is possible with a bioavailable phosphorus supplement.
    • Article

      Polyculture of milkfish Chanos chanos (Forsskal) and the red seaweed Gracilariopsis bailinae (Zhang et Xia) in brackish water earthen ponds 

      NG Guanzon Jr., TR de Castro-Mallare & FM Lorque - Aquaculture Research, 2004 - Wiley-Blackwell
      Growth, net production, and survival rates of milkfish cultured with Gracilariopsis bailinae at two stocking density combinations (T1– 30 fingerlings 100-m−2 pond+1-kg G. bailinae 4-m−2 net cage, T2– 30 fingerlings 100-m−2 pond+2-kg G. bailinae 4-m−2 net cage) in brackish water earthen ponds over four culture periods were determined. The control (T3) was stocked at 30 fingerlings 100-m−2 pond. Specific growth and production rates of G. bailinae were also calculated. There were no significant differences in mean growth, survival, and net production rates of milkfish between the three treatments. Irrespective of stocking singly or in combination with G. bailinae, significantly higher mean growth and mean production rates for milkfish were obtained during the third culture period of year 1 than those obtained from the other culture periods. Survival rates were not significantly different among the four culture periods. There were no significant differences in mean specific growth and mean net production rates between the two stocking densities of G. bailinae. Significantly higher mean specific growth and mean net production rates of red seaweed were also obtained during the third culture period of year 1 than those obtained from other culture periods. The production of milkfish and red seaweed was higher during the dry season. Growth rates of milkfish was positively correlated with temperature and salinity, while net production rates were positively correlated with temperature and total rainfall, but was inversely correlated with dissolved oxygen. G. bailinae growth and net production rates were positively correlated with water temperature and salinity. Results show that milkfish can be polycultured with G. bailinae grown in net cages in brackish water ponds at stocking density combination of 30 fingerlings 100-m−2 pond+1-kg G. bailinae 4-m−2 net cage.
    • Article

      Sargassum Studies in Currimao, Ilocos Norte, Northern Philippines II. Seasonal Variations in Alginate Yield and Viscosity of Sargassum carpophyllum J. Agardh, Sargassum ilicifolium (Turner) C. Agardh and Sargassum siliquosum J. Agardh (Phaeophyta, Sargassaceae) 

      AR Ragaza & AQ Hurtado - Botanica Marina, 1999 - Walter de Gruyter
      The yield (%) and viscosity (cps) of alginate from Sargassum carpophyllum, S. ilicifolium and S. siliquosum collected along the inter- and subtidal zones of Currimao, Ilocos Norte were determined monthly for a period of one year. Results show that each species demonstrated an individual pattern of alginate characteristics which is significantly influenced by the collecting zone, fertility state, and collecting month (P < 0.05). Positive correlations were observed in alginate yield and viscosity with species and fertility states. Among the three species, S. ilicifolium is the best species for alginate production for the food industry based on viscosity characteristics, followed by S. siliquosum and S. carpophyllum.
    • Article

      The seasonality and economic feasibility of cultivating Kappaphycus alvarezii in Panagatan Cays, Caluya, Antique, Philippines 

      AQ Hurtado, RF Agbayani, R Sanares & MTR de Castro-Mallare - Aquaculture, 2001 - Elsevier
      Vegetative thalli of brown and green Kappaphycus alvarezii were cultivated in Panagatan Cays, Caluya, Antique, Philippines, over 60- and 90-day periods using hanging-long line (HL), fixed off-bottom (FB), and hanging long line–fixed off-bottom (HL–FB) methods to determine the daily growth rate and yield. A completely randomized design experiment with six replicates of 5-m line cultivation rope was used in the study. An economic analysis was prepared to determine the viability of the culture systems used. To determine the effect of strain, culture technique, culture days and culture month on the daily growth rate and yield, a combination of these different factors was treated as a single treatment. Results show that at 60-day culture period, daily growth rate and yield in all techniques were lowest in July–August and highest in January–February. Higher growth rate (2.3–4.2% day−1) and yield (3.6–15.8 fresh weight kg m−1 line−1) were obtained from September to February. Significant differences (P<0.05) in growth rate and yield were determined between culture months. At 90-day culture period, there were no significant differences in growth rate and yield between culture months; however, a significant difference was found between culture techniques. The average production (dry weight kg crop−1) of K. alvarezii when grown at 60-day culture period during lean and peak months using HL, FB and HL–FB techniques ranged from 421 to 3310 kg with HL–FB the highest and FB the lowest. Net income, return on investment (ROI) and payback period were all positive during peak months, but negative values were obtained during lean months. Only seaweed grown on HL technique during the peak months at 90-day culture period showed positive income, ROI and payback period. The seasonality of cultivating K. alvarezii is shown in this present study. This paper further shows the best culture technique to be adopted at certain months of the year to produce the highest yield and income.
    • Article

      Use of juvenile instar Diaphanosoma celebensis (Stingelin) in hatchery rearing of Asian sea bass Lates calcarifer (Bloch) 

      MR de la Peña - The Israeli Journal of Aquaculture-Bamidgeh, 2001 - Society of Israeli Aquaculture and Marine Biotechnology
      The effects of size, dry mass intake and nutritional value of the brackishwater cladoceran, Diaphanosoma celebensis, on the growth and survival of 15-30 day sea bass (Lates calcarifer) larvae reared in a static green water system were determined. The highest specific growth rate (29.4%/day) was attained in larvae fed a 1:1 combination of Artemia nauplii and adult Diaphanosoma but it was not significantly different (p>0.05) from fish fed only adult Diaphanosoma (28.8%/day) or only juvenile instar Diaphanosoma (28.6%/day). Survival rates of larvae (92.4-99.0%) fed the different live diets did not significantly differ (p>0.05). Larvae markedly prefered juvenile instar Diaphanosoma over Artemia nauplii and adult Diaphanosoma. The crude protein contents of juvenile Diaphanosoma (58.7%), adult Diaphanosoma (58.3%) and Artemia (56.7%) were substantially high and satisfied the dietary protein requirements of larvae. The fatty acid profile of the sea bass fry reflected the lipid composition of the live diet. Improved growth, survival and dry mass intake in larvae indicate the potential of juvenile Diaphanosoma in the hatchery rearing of sea bass larvae.