Recent Submissions

  • Book chapter

    Evaluation of fertilizer use and milkfish yields in Palawan 

    EB Dumada-ug & R Sevilleja - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Milkfish yields in Palawan in 1993–94 were low, only 595 kg/ha-yr on average and ranged 100–700 kg/ha-yr in 35 of 50 farms surveyed. Only seven farms had yields between 1,000 and 1,800 kg/ha-yr. Yields were higher in deeper ponds, and shallowness of ponds was a major constraint to high yields. Farm -gate prices of milkfish ranged from P25 to P55 and averaged P42. The prices of milkfish were on average 43x greater than the price of organic fertilizers (chicken manure) and 6x more than the price of inorganic fertilizers. The income from milkfish made up 10-95% and averaged 53% of the total income of the farmers. One crop cycle a year was the practice in 28 of the 50 farms; 20 farms had two crops, and two farms went for 3–4 crops a year. A crop cycle was 3–4 months long in 14 farms, 5–6 months in 29 farms, and 7–9 months in 7 farms. Crop cycles started with draining and drying the ponds and applying fertilizers to grow natural food. Most of the farms were supplied by tidal water and water exchange in the ponds was done every spring tide in 33 farms. The other farms changed water once a month, once or twice in a crop cycle, or once a year. Application rates of organic fertilizers were mostly less than 1 ton/ha-yr and averaged 515 kg/hayr, but three farms used as much as 1,250 kg/ha-yr, and one farm used 3,000 kg/ha-yr. Half as much inorganic fertilizers were used; the average for the 50 farms was only 211 kg/ha-yr, but one farm used as much as 1,350 kg/ha-yr. The fertilizers encouraged natural food to grow in the ponds. Two of the farms grew mostly plankton, 15 grew the benthic mat lablab, and 33 grew the green filamentous algae lumut. None of the farms used commercial feeds. Stocking rates varied widely among the farms, ranged from 1,000 to 60,000 fry or fingerlings per hectare per year and averaged 8,000/ ha-yr. Two-thirds of the farms stocked less than 7,000/ha-yr, but eight farms stocked fry or fingerlings at much higher rates of 13,000–60,000/ ha-yr. An input use variation model showed that milkfish yield was a function of the ratios of prices of milkfish to prices of organic and inorganic fertilizers; pond water depth and salinity; milkfish income as percent of total income; family size; membership in aquaculture association; and contacts with government‘s extension services and information dissemination system. The surveyed farms ranged from 3 to 40 years old, with 92% under 20 years; they had been in operation 1–23 years, 76% of them for less than eight years. Of the 50 farms in the survey, only nine were private (titled) lands, 34 were covered by fishpond lease agreements (FLA issued by the Bureau of Fisheries and Aquatic Resources), and the others had only survey documents or no papers at all. Farm sizes ranged 0.8–50 ha (average 12.5 ha), and 52% of them were smaller than 6 ha. The private farms were small, only 1–7 ha except one that was 25 ha. The FLA farms were much larger, and 23 of them were 5–50 ha. Large parts of the large farms were not operational, and 90% of the farms used effective areas of less than 7 ha. The low lease fees for FLAs evidently did not encourage farm development to increase yields. The farms had mostly shallow ponds 25–100 cm deep (average 68 cm).
  • Book chapter

    Development of various value-added products from 'aloy' or bullet tuna Auxis rochei 

    EEM Santos-Yap - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    The recommended steps in new product development were followed to utilize bullet tuna maximally. New products were generated, evaluated, and refined. Three product concepts were initially advanced to the product optimization stage; both product and positioning blueprints were created. The products were optimized in terms of the levels and combinations of additives and spices, and the organoleptic properties were evaluated. The new products—bullet tuna loaf, seasoned dried bullet tuna, canned spicy bullet tuna, and canned pet foods—were tested for shelf-life. Tuna loaf treated with potassium sorbate remained acceptable for 29 days at 0°C, whereas untreated samples remained acceptable for 26 d at 0°C, 16 d at 14°C, and 3 d at 35°C. Seasoned dried tuna was still acceptable until 15 d in storage at 0°C and until 6 d at 35°C. Canned spicy tuna remained acceptable after more than a year of storage at 35°C. Cost analysis based on the current retail prices of bullet tuna (P30/kg), additives, spices and other raw materials showed that the production costs were: P19 for 100 g of bullet tuna loaf; P2 for a piece of seasoned dried tuna; and P 12.5 for a can of spicy bullet tuna. Traditional processing methodologies were applied to bullet tuna as raw material. Smoking and dry-salting yield bullet tuna products that can be offered to the consumers at prices much lower than those of the newly developed value-added products.
  • Book chapter

    Demonstration of tilapia-carp polyculture in lowland and highland farms 

    AL Palma, RM Pol & AS Diamante - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Technology demonstration was conducted in three selected lowland freshwater ponds in Lucban, Quezon and in three highland ponds in Ifugao. The ponds varied in location, size, water source, and operators. The polyculture system included 60% Nile tilapia, 30% common carp, and 10% bighead carp, seeded at a density of 5/m2. Two lowland ponds had total production of 4,737 and 4,416 kg/ha-yr (8.83 kg/m3 and 6.77 kg/m3). One highland pond yielded 2,786 kg/ha-yr (11.14 kg/m3). Survival rates were better in lowland areas, mostly because the farmer cooperators had better training and more experience. Costs-and-returns analysis showed high profitability of tilapia-carp polyculture. With proper management, polyculture can produce fish and increase farmers‘ incomes, even during the off-season for traditional crops.
  • Book chapter

    Growth and yield of the grouper Epinephelus coioides fed 'trash fish' at different rates and frequencies in floating net cages 

    GV Galzote & EC Abrera - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    The effects of various feeding rates and frequencies on the growth and survival of orangespotted grouper Epinephelus coides were determined in floating net cages in Tiniguiban Cove, Puerto Princesa, Palawan. Juveniles (average weight 60 g) were stocked in 2 m x 2 m x 1.5 m cages at a density of 10/m3. The experiment tested six treatments: 10% of body weight (BW) daily; 5% BW daily; ad libitum daily; 10% BW every other day; 5% BW every other day; and ad libitum every other day. After five months, the fish fed at 10% daily had 100% survival and the highest weight gain (520 g), growth rate (3.5 g/d), net production (31.44 kg), and gross income (P5,463). However, returns were negative in all treatments because of either too high feed consumption and poor conversion or low net production.
  • Book chapter

    Yield and agar quality of three red seaweed Gracilaria species grown in tanks at three salinities 

    MSR Ferrer & AN Marasigan - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Gracilaria changii, G. firma and G. tenuistipitata were collected from the eastern coast of Sorsogon in southeastern Philippines and grown in concrete tanks at the SEAFDEC Aquaculture Department in Iloilo in May-June and in September-October 1994 at a stocking density of 1 kg/m2 and at three salinities (15, 25, and 35 ppt). In the first run, the highest specific growth rates per day were 2.5% at 25 ppt for G. changii, 3.6% at 35 ppt for G. firma, and 3.2% at 15 ppt for G. tenuistipitata. In the second run, the highest daily growth rates were 1.4% for G. changii, 1.2% for G. firma, and 3.3% for G. tenuistipitata, all at 15 ppt. Nutrient and light limitation in the second run led to lower and even negative growth rates. Gracilaria changii and G. firma were euryhaline but grew best at 25–35 ppt; G.tenuistipitata was not euryhaline and grew best at 15 ppt. The highest growth rates in tanks were at salinities close to those in the natural habitat: G. changii at 25 ppt, G. firma at 35 ppt, and G. tenuistipitata at 15 ppt. The estimated potential production (dry weight kg/m2-yr) in tanks was 1.65 kg G. changii at 25 ppt, 2.49 kg G. firma at 35 ppt, and 2.35 kg G. tenuistipitata at 15 ppt.

    Agar yields from three Gracilaria species varied from 5% to 23%, on average lowest in G. tenuistipitatata, and were generally higher at 25 ppt and 35 ppt than at 15 ppt. Agar gel strengths were also strongly affected by salinity and were highest at 35 ppt. Gracilaria tenuistipitata had very high gel strength (average 782 g/cm2 but as high as 1,082 g/cm2 comparable to agarose), well above the specified 750 g/cm2 for the international market. Gracilaria changii and G. firma had average gel strengths of 516 and 558 g/cm2, well within the range (400–600 g/cm2) for commercial agar used in the food industry. The sulfate contents were lower at 15 ppt and were even 0% in several instances, especially in G. tenuistipitata. The gelling temperature of 32°C and melting temperature of 97.3°C qualifies G. tenuistipitata for the international market. Gracilaria changii and G. firma had melting temperatures of 93–95°C but gelling temperatures of just 29°C. Farming techniques for these seaweeds should be developed to produce enough raw material for profitable commercial processing.
  • Book chapter

    Transplantation, hatchery, and grow-out of window-pane oyster Placuna placenta in Guimaras and Iloilo 

    SS Garibay, SN Golez & AS Unggui - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    The windowpane oyster Placuna placenta (local name kapis) used to be harvested in large quantities and support a shellcraft industry in the Philippines, particularly in Panay Island. But the fishery and the industry declined markedly by the 1990s. Studies were conducted to transplant kapis and also to develop hatchery techniques for it in an effort to counter the population depletion. Kapis with average shell heights of 7 cm and 10 cm were transplanted from Roxas City in northern Panay Island and from Oton, Iloilo in southern Panay to Taklong Island in Guimaras during the rainy season (July–November) and the dry season (February–June). Survival of the transplants was higher during the dry season (57–60%) than during the rains (35–48%). Sexually mature kapis 10 cm in shell height were induced to spawn by temperature manipulation, water level manipulation, and use of ultravioletirradiated sea water. Spawning was successfully induced by raising the water temperature to 29±0.5oC. Eggs measured 45 μm on average, and fecundity was 5,000–10,000 per female. Kapis larvae were reared on a combination of the microalgae Isochrysis galbana, Tetraselmis sp., and Chaetoceros calcitrans, maintained at a density of 100,000 cells/ml. Three water treatment schemes were tested for larval rearing: chlorination, ultraviolet irradiation, and filtration (control). Larvae survived to the umbo veliger stage (180 μm, day 10) in chlorinated sea water whereas mass mortality occurred at the straight-hinge stage (days 4–) in both UV-treated and filtered sea water.
  • Book chapter

    Grow-out of the tiger shrimp Penaeus monodon in floating net cages in Batan Bay, northern Panay 

    JG Genodepa, MJ Sanoy & G Banehit - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    The effects of two stocking densities and two feed combinations on growth, survival and production of the giant tiger shrimp Penaeus monodon in floating net cages were studied in an attempt to refine the existing technology on cage culture of tiger shrimp for the benefit of small- and medium-scale fish farmers. Four treatments were tested, replicated in time: stocking density of 100 shrimp/m2, feeding with 70% commercial shrimp pellets P and 30% 'trash fish' F; 100 shrimp/m2 and 50% P + 50% F; 200 shrimp/m2 and 70% P + 30% F; and 200 shrimp/m2 and 50% P + 50% F. Harvested after 93–95 d, the shrimps at the lower density treatments were significantly larger and had greater proportion of good sizes (>18 g body weight). Although the combination of 70% P + 30% F resulted in better growth, the combination of 50% P + 50% F resulted in more good-size shrimps. Survival, production, and gross income were not significantly different among treatments. None of the treatments in this study was economically viable. Gross income was very low due to poor growth and survival, mostly due to luminous vibriosis, then a new disease that eventually wiped out many shrimp hatcheries and ponds around Panay Island.
  • Book chapter

    Grow-out of milkfish in net-walled marine pens in La Union 

    ND Domenden - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Grow-out of milkfish in 125 m2 net-walled marine pens was tested in Santo Tomas Cove, La Union at three stocking densities of 6, 9, and 12 fish/m2 and using commercial feed (crumbles and pellets) with 25–30% crude protein. After 115 days, survival of milkfish in marine pens was 92–97%. Fish stocked at 12/m2 or 1,500/pen grew to average weights of 286 g, larger than the fish stocked at lower densities. Feed conversion ratio was 2.3 at the highest density and worse at the lower densities. Costs and returns of milkfish grow-out in marine pens at three densities showed that feeds were the most costly component (55–69%) of production. The milkfish harvest was equivalent to about 33 mt/ha at the stocking of 120,000 fish/ha. Only at this high density was adequate profit made for a 48% return on investment per crop. Two crops are possible in the Ilocos region during the dry season from November to June. Grow-out of milkfish in marine pens can be improved if seed and feeds could be procured at lower cost.
  • Book chapter

    Socioeconomic profile of tuna fishers in northwestern Luzon 

    VR Panay & NL Ledda - In TU Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    A study of tuna fishers in northwestern Luzon (Region I) was done by means of a questionnaire. The 511 respondents included 178 from Ilocos Sur, 200 from La Union, and 133 from Pangasinan. Most of them were younger than 50 years, had basic education, married with large families of 3-9 children, owned the houses they lived in, and had low annual incomes of about P35,000. Fishing was their sole means of livelihood for almost all the respondents, except some for whom farming supplemented the income from fishing. Majority worked every night or day, 36% went fishing every other night or day, and 13% went fishing five times a week. Most fishers went out to sea at night. Fully 52% of the fishers worked within 50 km from shore; 38% fished within 51–100 km, and the others went out farther than 100 km and even 200 km. La Union fishers worked closest to shore (average 38 km) and Pangasinan fishers the farthest (average 92 km). More than 90% of all fishers used motorized bancas, which made it possible for them to fish farther out to sea. Only 36% of the fishers owned the boats and fishing gears they used, and most did not. In all three provinces, the capital for the fishing enterprise came mainly from savings. The average cost of motorized boats was P31,200; non-motorized boats, P1,200. Longlining was the most preferred fishing method in the region. Hand lining was the second most preferred in Ilocos Sur and Pangasinan. Gillnetting and other methods (rabuk, kawil, pana, and bira-bira) were ranked third and fourth, and trawling was the least preferred. Drift gill nets used for tunas cost on average P680; tuna long lines, about P600; tuna hand lines, P345; and troll lines, P750. The main species caught by the fishers were skipjack tuna, yellowfin tuna, frigate tuna, Spanish mackerel, rainbow runner, dolphinfish, sailfish, blue marlin, and threadfins. In Ilocos Sur, most fishers reported catches of 11-20 kg in one trip, and a few fishers caught 50 kg. Spanish mackerel and sailfish gave the fishers better incomes than the other species. Fish catches and prices and fisher incomes in La Union were lower than in Ilocos Sur. Threadfins were more abundant in La Union. Fishers in Pangasinan did not catch sailfin, marlin, or threadfins, but caught higher volumes (20–60 kg/trip) of the other species.
  • Book chapter

    Use of soybean meal and rice bran in formulated diets for the grouper Epinephelus coioides 

    ET Marasigan, SL Miag-ao & AE Serrano - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Two diets were formulated to include 8–14% soybean meal and 9–18% rice bran, 34–40% fish meal, 4–5% mussel meal, and 7–8% Acetes shrimp meal, and 11–13% cod liver oil. Soy bean meal and rice bran were included at 4:1 ratio together to replace 12.5% and 25% of the animal protein sources in the two diets. The two diets were prepared in dry D form and moist M form. The four test diets, D12.5, M12.5, D25, and M25 diets had 40–42% protein and 4,000 kcal/g gross energy. The control diet used was a dry diet with 44% crude protein and 4,260 kcal/g, made with 30% Peruvian fish meal, 8% squid meal, 22% Acetes shrimp meal, 8% cod liver oil, 8% soybean oil, but no plant protein sources. The five diets were fed to juvenile grouper (mean weights ranging from 1.63 ± 0.47 to 2.41 ± 0.91 g) in indoor 400 L concrete tanks (10 fish per tank). After 10 weeks, growth, feed intake, feed conversion ratios (1.2–2.2), and survival (60–80%) of juvenile grouper were not significantly different between the test diets and the control. The carcass composition of the harvested grouper was not significantly different among diets. Protein utilization was best among the fish fed the test diet D12.5. This study showed that soybean meal and rice bran at 4:1 ratio can be included in formulated diets for grouper to replace 12.5% to 25% of the animal protein sources. However, the results for the test diets may also have been due to other factors - the high fish meal content, inclusion of mussel meal, and increase in cod liver oil.
  • Book chapter

    The tuna fishery off northwestern Luzon: catch of purse seines and hand lines operating around fish-aggregating 'payaw' 

    VV Prado - In TU Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    The tuna fishery along northwestern Luzon was studied from March 1994 to April 1995. About 120 units of fish aggregating ‘payaw’ were set 20–100 km offshore and fished by about 350 handline boats and 6 purse seines. The handline landing areas were in Apatot, San Esteban, Ilocos Sur and in Darigayos Cove, La Union. The resident purse seine was based at Poro Point in San Fernando, La Union; the others were occasional operators. Skipjack tuna Katsuwonus pelamis was the primary species landed by the purse seine and yellowfin tuna Thunnus albacares was mostly landed by the hand lines. These species occurred year-round with peaks during the dry season. The purse seine was operated about 9 sets per month, and landed an average of 51 mt fish monthly (catch rate 5.7 mt/set), highest in November, December and March. Handline fishing was carried out an average of 17 days a month (catch rate about 19 kg/boat-day). The tuna fishery was adversely affected by strong monsoon winds and typhoons. The rough seas inhibit fishing and give the tuna populations much needed respite from the intense fishing pressure.
  • Book chapter

    Diet and sexual maturity of yellowfin and skipjack tuna taken by hand lines from fish-aggregating 'payaw' off northwestern Luzon 

    JR Mamhot & ER Verceles - In TU Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Skipjack tuna Katsuwonus pelamis and yellowfin or albacore tuna Thunnus albacares taken by hand lines from the 'payaw' off La Union and Ilocos Sur were sampled from April 1994 until August 1995. Skipjack ranged from 28 cm to 59 cm in fork length and from 0.35 to 4.2 kg in weight. Yellowfin ranged 24–67 cm and 0.25–6.4 kg. The common size landed was about 40 cm for both species. Size at first maturity of skipjack was about 41 cm in males and 42 cm in females. The yellowfin tuna taken by hand lines were almost all immature except two mature males about 60 cm long. About 18 prey species were identified in the stomachs of skipjack, and about 25 prey species in yellowfin. The preferred prey were mantis shrimps and squids. Small fishes and other invertebrates were also eaten. Mesopelagic lanternfish were eaten by yellowfin and epipelagic jellyfish were eaten by skipjack.
  • Book chapter

    Collection of the mud crab Scylla serrata var paramamosain in Tinagong Dagat and Sapian Bay, northern Panay 

    NB Solis - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Mud crabs were collected by baited traps from the mangroves and estuaries of Tinagong Dagat Bay and Sapian Bay in Capiz, northern Panay monthly over 18 months. Scylla serrata var paramamosain made up 95.4% of the collection and Scylla oceanica, 4.6%. Mean catch rates of S. serrata from Tinagong Dagat was 0.4 crabs/trap in the mangroves and 0.5 crabs/trap in the estuary; in Sapian Bay, 0.9 crabs/trap in both habitats. In both bays, S. serrata occurred year round, but at greater abundance during the rainy season (June–September). Most crabs were 2–10 cm in carapace width, but some were up to 14 cm. Crabs were smaller in the mangroves (modal size 5 cm) than in the estuary (modal size 8 cm). The smallest crabs (2 cm) were collected in the mangroves in January and May, and the 3 cm crabs occurred most months except June, August, September, and November. The presence of smaller crabs in greater numbers in the mangroves indicates affinity for shallow, sediment-laden habitat with plenty of shelters in the form of mangrove roots and leaves. Very few crabs over 8 cm were captured in the mangroves. Crabs of 4–14 cm were captured in the estuaries, the 12–14 cm ones during July–October. The samples at each site formed several size groups every month, and ‗cohorts‘ could be discerned and followed over the next months. It was estimated that the 2–4 cm size group in January–May reached the size of 8–10 cm by October–November. Juvenile mud crabs apparently spent one year in the mangroves or estuaries. There were more males than females (1F:1.2M) in Tinagong Dagat, but the other way around (1M:1.3F) in Sapian Bay. Berried crabs of 14 cm were occasionally caught by filter net in Tinagong Dagat.
  • Book chapter

    Competitive and comparative advantages of brackishwater aquaculture of tiger shrimp, mud crab, and milkfish in the Philippines in 1985-1995 

    LA Gonzales, CD Elca, VA Gonzales, PA Alviola IV, FJ Paraguas & C Olalo - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    The brackishwater aquaculture sector contributes considerably to the growth of the fisheries sector. Tiger shrimp Penaeus monodon, mud crab Scylla serrata, and milkfish Chanos chanos, in particular are efficient users of domestic resources and earners of foreign exchange. These three commodity sectors have not been fully developed because of inadequate policies in research, technology generation, and extension, and in public investment and support services in production, marketing, and post-harvest processing. Our analysis used the domestic resource cost approach. The average resource cost ratios for the Philippines were 0.44 for tiger shrimp, 0.66 for mud crab, and 0.35 for milkfish. If the peso overvaluation is corrected, the comparative advantage can be dramatically enhanced with respective resource cost ratios of 0.36 and 0.55, and 0.28. Given the current international market and production technologies for these commodities, competitive and comparative advantage can be sustained above the breakeven border price per kilogram of US$6–7 for tiger shrimp, US$5–6 for mud crab, and about US$1 for milkfish. The actual border prices per kilogram during the past five years have been higher at US$12.34 for tiger shrimp, US$8.39 for mud crab, and US$2.39 for milkfish. At current domestic costs and border prices of the these commodities, the advantage in exports may be sustained at yields per hectare greater than about 2 mt tiger shrimp, 100 kg mud crabs, and 500 kg milkfish. To enhance the efficiency of production of these commodities, the following areas of intervention are needed:
    • Technology improvements in seed production from the hatchery of tiger shrimp, mud crab, and milkfish
    • Research and technologies for diagnosis, prevention, and control of diseases of tiger shrimp (e.g. luminous bacteria)
    • Training in farm management to enhance the skills of small-scale pond operators
    • Public investments in infrastructures and support services including credit access to enhance efficient flow of goods and services from the farm to strategic market outlets
    • Market development to ensure sustainable outlets for brackishwater pond production
    • Reforms in trade and exchange rate policies to enhance global competitiveness
  • Book chapter

    Bacteria and toxin isolated from the dinoflagellate Pyrodinium bahamense var. compressum and production of monoclonal antibodies and diagnostic kits to monitor red tide and toxic mussels 

    TM Espino, RM Aspiras, NG Sabino, E Parreño, RL Macasadia & MLF del Mundo - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Six bacterial isolates obtained from the red tide dinoflagellate Pyrodinium bahamense var. compressum were found to be toxic. The most toxic isolate MM-11 was cultured, characterized, and identified to be Micrococcus luteus. MM-11 and M. luteus had similar DNA bands on agarose gel, and contained 70.0–75.5% mole G+C. Several Micrococcus species were isolated from pure culture and field samples of Pyrodinium and from red tide affected mussels. MM-11 and the other Micrococcus isolates tested positive for saxitoxin. MM-11 was grown on seawater agar; peak cell density of 1.36 x 1010 cells/ml occurred after 3 days of incubation. Toxin production was directly proportional to cell density. The crude toxin from the optimized culture of MM-11 resulted in death of mice in only 1.8–2.4 min, equivalent to a toxicity of 5.9–13.4 mouse units. MM-11 was inoculated into healthy mussels and yielded bacterial isolates that had characteristics of MM-11, and extracts of toxin similar to MM-11 toxin. Mice injected with extracts from the inoculated mussels showed symptoms of paralytic shellfish poisoning (dyspnea 12–15 min after injection), but did not die. Partially purified extracts from red tide affected mussels killed mice in 3.4 min, equivalent to a toxicity of 3.4 mouse units. Addition of 5, 25 and 50% coconut milk to this toxin extract reduced the toxicity to only 34%, 29%, and 25% of that without coconut milk. The ELISA test similarly showed reduction of saxitoxin concentration from 4.78 g toxin/g at 5% added coconut milk to 3.62 g toxin/g at 50% added coconut milk.

    PSP toxins were extracted from bacteria and red tide affected mussels. The 24 purified extracts of MM-11 toxin were shown by mouse bioassay to have concentrations from 0.6 to 71.6 μg toxin/g bacteria. Green mussels sampled from Bataan and Zambales during incidence of red tides from 1994 to 1998 contained lower amounts of toxin per unit weight than the bacterial extracts. Analysis of the MM-11 toxin by HPLC-fluorometry showed two fractions similar to those of standard gonyautoxin 1 and gonyautoxin 3.
  • Book chapter

    Shrimp pond effluents and water quality in Imbang River, Negros Occidental 

    ET Taberna - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    The contribution of shrimp farm effluents to the pollution load in Imbang River, Negros Occidental was measured during the period May 1993 to February 1995. Shrimp pond effluents were characterized and the pollution load estimated. The pond effluents had low average nitrite (0.0025 ppm) and nitrate (0.06 ppm) and optimum (for shrimp culture) pH 7.9, phosphate 0.15 ppm, dissolved oxygen 5.20 ppm, and salinity 23.3 ppt. Ammonia was 0.13 ppm on average in most farms, above the safe level for shrimp, and total suspended solids was 23 ppm, about 2.5x the allowed limit for effluents. Biochemical oxygen demand (20 ppm) and settleable solids (0.15 ppm) were still with acceptable limits. Residues of organochlorine pesticides were present at very low concentrations, well below the safe levels for aquatic life. Most of the pollution load came from the regular water exchanges over the 4-month crop cycle, at least every two weeks in low-density farms and more frequently in the high-density farms. The total draining of pond water at harvest contributed a minor load. Total solids from shrimp farms contributed a huge load, about 181,325 mt/yr. Total suspended solids contributed 1,285 mt/yr and settleable solids <1 mt/yr. The total BOD load was 154,367 kg/yr. The phosphate load was about 1,080 kg/yr, and the total nitrogen load was 1,225 kg/yr. The effects of effluent release from farms were localized. Upstream water quality and other uses of the river were not affected. Since most of the shrimp farms were located 1.5–2 km from the sea, the release of effluents during water exchange and at harvest did not adversely affect water quality downstream of these farms. Where such draining increased the levels of ammonia, phosphate, and total suspended solids in the river, the effect was significant only within 250 m from the release point, and the pollutants were dissipated about 550–800 m downstream The other water quality variables were at low levels in the pond effluents and did not affect the river water during draining. Often the concentrations of pollutants in the river were higher before than during draining of pond effluents. Stations upstream of the release sites of pond effluents often had high pollutant concentrations from other upstream sources.
  • Book chapter

    Sugar mill effluents and water quality in Imbang River and Malisbog River, Negros Occidental 

    HJ Gonzales - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    The effluents of two sugar mills and the effects on water quality in the receiving rivers were studied. Sugar mill A was located in Barangay Dos Hermanas in Talisay and discharged directly into Imbang River. Sugar Mill B was located in Barangay Hawaiian in Silay City and discharged into Malisbog River, a tributary of Imbang. Both sugar mills had sedimentation tanks and lagoons for partial wastewater treatment prior to discharge. Water sampling was done at 13 stations at effluent discharge sites and also upstream and downstream of these sites. The sugar mill effluents were particularly high in biochemical oxygen demand (BOD 109–419 mg/l), total suspended solids (168–384 mg/l), and total solids (1,185–1,234 mg/l), also high in ammonia (0.2–0.5 mg/l) and water temperature (31–38°C), but low in dissolved oxygen (2–5 mg/l). Measured stream flows varied at the different stations and were generally lowest at stations near sugar mill A and at stations near sugar mill B. At these sites, the depth of Imbang River varied from about 10 cm during low water flow in December–May to about 2 m during high water flow in June–November. During normal low flows, the sugar mill effluent comprised 75–85% of the total stream volume, causing highly polluted conditions immediately below the outlets. Sugar mill A discharged high annual loads of solids, BOD, nitrate, and phosphate into Imbang River, whereas sugar mill B loaded plenty of solids, BOD, ammonia, and phosphate into Malisbog River. The sugar cane milling season in Negros Occidental started in October and ended in May, coincident with the dry season. Significantly higher levels of BOD and nutrients, but lower DO, were observed in the river during the milling season (see figures in Gonzales et al., this volume), both because of greater discharge and lower dilution by lower stream flows. River water quality was better at the stations upstream than downstream of the sugar mills. Stations near the sugar mills had BOD, ammonia, and solids at concentrations exceeding the allowable limits set for river water by the Department of Environment and Natural Resources.
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    Treatment of shrimp pond effluents by sedimentation and by seaweed and mussel biofiltration 

    NR Fortes & VL Corre Jr. - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Tiger shrimp Penaeus monodon were stocked in three 1,000 m2 ponds at 12,000 juveniles/pond and grown for 141 days. Water quality in the ponds was monitored over the grow-out period, particularly before and after every water change. BOD, chlorophyll a, and total dissolved solids of the effluent increased over the grow-out period due to increased biomass and feed input. Similar trends were observed for inorganic nitrogen, reactive phosphorus, total suspended solids, and hydrogen sulfide. Concentrations decreased after draining and reflooding. Soil samples also showed increases in organic matter available phosphate, carbon, and nitrogen content over the grow-out period.

    Effluents from semi-intensive shrimp ponds were discharged into eight treatment ponds (each 200 m2): three sedimentation ponds, three with Gracilaria stocked at 20 kg/pond, and two with mussels stocked at 10/m2. Measurements were made of pH, ammonia, nitrite, nitrate, reactive phosphorus, biochemical oxygen demand, chlorophyll a, total suspended solids, and total dissolved solids in the water in the treatment ponds after effluent addition, one week and two weeks later, and before draining. Soil pH, organic matter, and phosphorus were also analyzed every two weeks. The changes in these variables were similar among the three treatments in the eight ponds. In this study, water quality of effluents improved after one week in the treatment ponds.
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    Assessment of grouper resources around Zamboanga City and Basilan, Philippines 

    NT Lasola, RA Samson & PB Domingo - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    A total of 2,643 kg of groupers were collected from six markets (96% of the biomass) and from prescribed fish traps in three fishing grounds (106 kg, 4%) around Zamboanga City and Basilan from November 1993 to October 1994. The collection included 26 species in seven genera: Aethaloperca, Cephalopholis, Cromileptis, Epinephelus, Niphon, Plectropomus, and Variola. The three species of highest biomass were Epinephelus fasciatus (26%), Cephalopholis sonnerati (14%) and Cromileptis altivelis (13%). The least biomass was contributed by Epinephelus sexfasciatus (0.1%), Plectropomus areolatus (0.1%), and Cephalopholis sexmaculatus (0.3%). Grouper biomass was lower from November to April and greater from May to October. Groupers caught by the prescribed fish traps were mostly Epinephelus merra (50% of the total). The highest catch of grouper was 0.8 kg/fish trap around Sta. Cruz Island in July, and the highest catch of all demersal fishes was 7 kg/trap around Malamawi Island in September. On average, groupers made up less than 10% of the monthly catch of fish traps. The groupers collected from the markets and from the fish traps averaged 28 cm in total length— all young juveniles. Cromileptes altivelis (average 38 cm) were the largest individuals and Plectropomus spp. (36 cm) similarly so. The largest C. altivelis (1.5 kg) was caught in December and the smallest (0.8 kg) in April and August. The various Cephalopholis species averaged 31 cm, and the various Epinephelus species were smallest at 26 cm. Groupers were largest in December and smallest between January and May. Length-weight equations were derived for seven grouper species. Of the 78 grouper stomachs that were dissected, 52 were empty and 26 contained food, mainly crabs, anchovies, hermit crabs, soldierfish, squids, and shrimps. Groupers with mature and ripe varies had from 3,000 to 11,000 eggs per gram ovary.
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    Adaptation of integrated fish-duck-pig farming system in Leyte 

    G Alcober - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Adaptation of a fish-duck-pig integrated farming system was conducted at the Busay Freshwater Experimental Farm in Babatngon, Leyte. Genetically improved farmed tilapia (GIFT) and common carp (at a ratio of 4:1) were stocked at densities of 3/m2 and 6/m2 in four earthen ponds; they were not given any commercial feed. Animal houses were built over the ponds and stocked with mallard ducks at a density of 375/ha, and piglets at 30/ha; they were given commercial feeds daily. After 154 days, the farming system produced a net yield of 1,685 kg fish/ha at a stocking density of 3/m2 and 2,808 kg/ha at 6/m2. Since water quality was not adversely affected, the higher stocking density of 6/m2 is a viable option. This farming system can be further improved and refined for better production and higher incomes.

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