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  • Book chapter

    Water quality in Imbang river, Negros Occidental: effluents and pollutant loads from agriculture, sugar mills, households, and shrimp farms 

    GA Gonzales, HJ Gonzales, RC Sanares & ET Taberna - In TU Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    An ecological assessment of Imbang River in Negros Occidental was undertaken from December 1992 to February 1995. The effluents from sugar mills, households, shrimp farms, sugarcane plantations and rice fields were characterized and their pollutant loads estimated. Water quality and invertebrate assemblages were analyzed at several sites along the river to determine the environmental status. Results showed significant seasonal and site variations in water quality along Imbang River. The dry season, coinciding with the milling season, was the more critical time of the year as water quality tended to deteriorate. The segments of the river near the sugar mills and households had the poorest water quality. Sugar mill effluents had high water temperature (average 33oC but as high as 50oC), low dissolved oxygen, high total solids, the highest settleable solids (average 2.5 and as high as 17 m/l), and the highest biochemical oxygen demand (average 259 ppm but as high as 14,800 ppm BOD). Domestic effluents had low pH, high ammonia, very high BOD, plus detergents or surfactants and high levels of fecal coliform bacteria. Agricultural runoff had high nitrate, high total solids, and the highest total suspended solids (average 296 ppm but as high as 5,095 ppm TSS). Shrimp ponds used saline water of average 23 ppt, and had the highest total solids (average 23,456 ppm and as high as 57,400 ppm). By far the major contributor of pollutant loads into Imbang River was agriculture, due to its huge areal extent and huge volume of water use and run-off. Agricultural run-off carried the highest annual loads of 7,858 kg phosphate; 6,495 kg ammonia; 794 kg nitrite; 67,212 kg nitrate; 16,987 metric tons settleable solids; 16,800,000 mt total solids, and 11,890,000 mt total suspended solids; but only 297 mt BOD. Sugar mill effluents had the highest BOD load (1,583 mt/yr) and also had high nutrient loads. Household effluents contributed the second largest loads of solids next to agriculture, and also added surfactants (966 kg/yr) and fecal coliforms into the river. The six shrimp farms at the lower reaches of Imbang River were a minor contributor of pollutants into the river, annually adding about 891 kg ammonia; 1,077 kg phosphate; and 181,325 mt total solids.
  • Book chapter

    Agricultural run-off and pollution in Imbang River, Negros Occidental 

    GA Gonzales - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    This study determined the concentration of key pollutants carried by agricultural run-off from the drainage area of Imbang River, Negros Occidental over a two-year period. The quantities loaded into the river were estimated to assess the contribution of agriculture to the degradation of the river. Agricultural production in sugarcane and rice plantations in the area relied on chemicals to control pests and enhance production. Run-off from agricultural land contained an average 0.2 ppm phosphate, 0.2 ppm ammonia, 0.02 ppm nitrite, and 1.7 ppm nitrate from fertilizer inputs and other sources. The run-off also had 7.4 ppm biochemical oxygen demand, 465 ppm total solids, 296 ppm total suspended solids, 0.4 ppm settleable solids, plus traces of organochlorine pesticides. The concentrations of all these potential pollutants were not alarming or dangerous, although on occasion, some exceeded the tolerable limits. However, increasing reliance on fertilizers often leads to intensified use and related problems. Likewise, the continuing use of chemicals to control field pests is of serious concern given that residues are easily carried by run-off to the nearest waterway and passed on and magnified through the food chain. The health of farm workers who routinely handle these products is at risk. Apart from commercial fertilizers, farm lands received organic wastes from domestic and industrial sources. Most farmers maintained farm animals such as carabaos, goats, and sheep that were allowed to graze on the fields after crops had been harvested. Grazing animals frequently left surface deposits of manure. Some farmers on occasion used sugar mill wastes as fertilizers and road fillers in the haciendas. Moreover, household wastes including human excreta were commonly disposed on nearby fields. The contributions of animal and human wastes to the total load of nutrients could be substantial but difficult to quantify given the manner of production and the varying composition of the wastes. Indeed, agricultural run-off transports non-point pollutants from so many poorly defined sources.
  • Book chapter

    Changes in the fish diversity and abundance on a heavily fished fringing reef on Santiago Island, Pangasinan, Philippines 

    JW McManus, CL Nañola Jr., RB Reyes Jr. & KN Kesner - In TU Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Fish assemblages on the reef slope, reef flat, and seagrass beds on Santiago Island were sampled over 18 months in 1992-1993 as part of a 6-year reef monitoring project started in 1986. Abundance and species diversity were analyzed by a variety of indices, and by multi-dimensional scaling and correlated ordered similarity matrix. The monitoring showed a distinct shift in the reef slope fish composition during the first half of 1988. Of the 100 most abundant species, 21 species showed significant reductions in abundance, and 20 species showed significant increases. Differences were not due to depth preference or feeding habits. Fishing pressure was apparently responsible for declines in Cheilinus trilobatus, Acanthurus nigricauda, and Naso literatus, as well as a general decline in the family Acanthuridae (surgeonfishes). However, analysis of site preferences of the decreasing species and the increasing species indicated a shift in community composition from those species preferring more coral cover to those preferring more sand, rock, and possibly Sargassum seaweed. Site preferences were determined from benthic life form transects done in 1992. Of 35 significantly changing species for which habitat data was obtained, 24 fit the hypothesis of habitat change. This supports the proposition from previous studies that the major cause of change in the reef slope fish community was the destructive fishing activity associated with Malthusian overfishing. Similar analyses of the fish assemblages on the reef flat and on the seagrass beds showed seasonal effects, particularly in the latter, but no strong shift comparable to that of the reef slope. These latter areas had been subjected to greater fishing pressure for a longer period.

    Reef fish populations such as those in Bolinao tend to be highly resilient provided the larval supply is not adversely affected. However, subtle changes in the cover of coral on a reef can lead to major changes in the composition of the fish community. Coral cover is being widely diminished on Philippine reefs, and substantial changes in the fish communities may be anticipated, even on reefs with initially low coral cover. These changes may affect the utility and immediate value of the fish to local fishers and the market systems they supply. It is of great urgency to stop destructive fishing practices such as blasting and use of cyanide, and to develop anchoring methods that are minimally destructive.

    There is a strong predictive relation between the numbers of fish (abundance) in an area and the numbers of species (biodiversity) they include. As fish populations decline due to destructive fishing, or highly concentrated non-destructive fishing, the local species richness may be expected to decline. This decline may have serious short-term social and economic consequences, as well as far-reaching long-term environmental effects. Efforts to reduce overfishing must be intensified—though reduction of birth rate, provision of alternative livelihoods, and curbing of destructive fishing — in order to prevent a very distressing future for the Philippine marine environment and the people it supports.
  • 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.
  • 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

    Bacterial loads in hatcheries and virulence of Vibrio spp. to larvae of the tiger shrimp Penaeus monodon 

    JL Torres - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Shrimp hatcheries are high-density systems and are prone to diseases. A small-scale and a large-scale hatchery for the tiger shrimp Penaeus monodon in Iloilo, Philippines were monitored over two months for water quality and shrimp survival. Water quality (water temperature, pH, salinity, dissolved oxygen, and specific gravity) was not significantly different between the two hatcheries. However, the small hatchery seemed to favor survival of eggs to early postlarval stages, whereas the large hatchery favored the survival of late postlarvae. The normal microflora and bacterial loads of tiger shrimp eggs, larvae, postlarvae, and rearing water were determined to identify the dominant bacteria and potential pathogens. Shrimp eggs harbored the lowest heterotrophic bacterial counts. The counts increased from the nauplii to the mysis stages, decreased during the mysis stage, and then gradually increased in the older larvae. Bacterial loads in the rearing water reflected those in raw sea water and reservoir-aged sea water. Vibrio, Pseudomonas, and Aeromonas were not detected in eggs but were found in postlarvae. Ubiquitous in sea water, these bacteria increased with the build-up of organic matter. The bacterial load in the water adversely affected larval survival. Forty bacterial strains were isolated from tiger shrimp eggs, larvae, postlarvae, from the feeds, and from the rearing water. These were tested for biochemical characteristics and segregated into eight groups or genera. Six genera were found in the mysis and five genera in the postlarvae. The Vibrio species were dominant. Only Escherichia spp. were present in feeds, whereas five genera were present in the rearing water. Only Vibrio and Pseudomonas were present in both larvae and water. Moraxella, Aeromonas, and Klebsiella were found in larvae but not in rearing water. Micrococcus and coryneforms were found only in rearing water. Four Vibrio isolates were tested for virulence against shrimp postlarvae at inoculation densities of 102 and 107 cfu/ml. The four Vibrio species caused mortality of postlarvae, and more at the higher inoculation density. The most virulent was Vibrio anguillarum—30% of postlarvae died after 24 h exposure to a bacterial density of 102 cfu/ml, and all larvae died after 48 h at 107 cfu/ml. Shrimp hatcheries must have protocols for hygiene and sanitation and for disease prevention and control.
  • Book chapter

    Domestic effluents and pollution in Imbang River, Negros Occidental 

    GA Gonzales - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Domestic effluents, or waste waters from human settlements, were sampled from eight stations along Imbang River in Negros Occidental from July 1993 to February 1995. Three types of domestic waste waters were produced by communities along Imbang River. Waste waters from clothes washing, house cleaning, and bathing, including washings of domestic animals and holding pens and run-off from rains and storms were conveyed by open canals and ditches to the river. This type of domestic effluents were well aerated and had the least potential to degrade the rivers. Waste waters from kitchens and markets carried large volumes of food scraps and other solid wastes, were unsightly, and smelled bad from the decomposition of garbage. Overflows from septic tanks were the most objectionable domestic effluents with offensive visual and olfactory properties. Domestic effluents had pH 4–7.6, dissolved oxygen of 0.5–7.2 ppm, and biochemical oxygen demand ranging from 2 to 240 ppm. The overflows from septic tanks were of the worst quality, with BOD 20x greater than household washings, and 6x more than kitchen and market effluents. Fecal coliform bacteria made up 93% of the total coliforms in the septic tank overflows, 86% in kitchen and market waste waters, and 39% in household washings. The domestic effluents from the communities around Imbang River had higher than allowable levels of BOD and solids. The 11 barangays with 16,486 households and 85,535 people loaded about 3,4000 m3 of waste water into the river every day. Along with the waste water were 180 mt/yr of BOD, 590 mt/yr of total solids, plus large quantities of nutrients, surfactants, and fecal coliform bacteria.
  • Book chapter

    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.
  • 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

    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.
  • Book chapter

    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.
  • 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

    Households, agriculture, industry, fishing, and fish farming along Imbang River, Negros Occidental 

    RC Sanares - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Interviews were conducted among respondents identified from the households, agriculture farms, sugar mills, and fish farms along the whole stretch of Imbang River, Malisbog River, and Muyao Creek, down to Barangay Balaring at the coast of Silay City in Negros Occidental. Among the 1,073 households, 11% used river water for washing clothes, but 20% also used the rivers for disposal of waste waters, 11% for human wastes, and 13% for animal wastes. Among the 30 respondents from the agriculture sector, 70% discharged water into the river. The two sugar mills in the area treated waste waters partially before release into the rivers; one sugar mill also released wastes in a nearby rice field. Milling wastes such as bagasse, molasses, and mud press were reused and not dumped into the river. Imbang River was both the water source and wastewater sink for seven fish farms.
  • 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

    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

    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

    The fish processing industry in Central Luzon and the processors' assessment of the extension program of the Department of Agriculture 

    MS Morata - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    A survey was done in 1992 of 242 fish processors in Region III or Central Luzon: 57 in Bataan, 39 in Bulacan, 24 in Nueva Ecija, 45 in Pampanga, 41 in Tarlac, and 36 in Zambales. The fish processors were engaged in three major fish processing enterprises: fish smoking (52%), fish drying (17%), and fish fermentation (31%). The products were smoked fish ‘tinapa’, dried fish ‘daeng’, fish paste ‘bagoong’, rice-fish paste ‘buro’, and fish sauce ‘patis’. Most of the processors in Zambales, Bataan, and Bulacan produced bagoong; ‘buro’ was produced only in Pampanga. Of the processors, 105 were small-scale operators, most of them in Pampanga, Bataan, and Bulacan, who had average capital of P11,000, worked an average of 3 days a week, and processed an average of 5,000 kg of fish a year. The 90 medium-scale processors had average capital of P20,000 and handled between 5,000 and 20,000 kg of fish a year, 5 days a week. The 47 large-scale processors, mostly in Zambales, Bataan, and Tarlac, invested an average of P94,000, and handled more than 20,000 kg of fish a year, seven days a week. The 242 fish processors in Region III in 1992 employed 501 people, 47% of them family members. The total production of processed fish products was about 73,000 kg a month, including about 21,511 kg ‘tinapa’, 4,790 kg ‘daeng’, and 46,634 kg ‘bagoong’. Processors in Zambales fermented the most fish, about 23,000 kg/month, followed by those in Bulacan. Among those in fish smoking, Bataan processors produced the biggest volume of 5,900 kg/month. Fish drying was done only in Bataan and Bulacan, and Bataan processors produced about 2,800 kg/month. The fish processors in Region III sold their produce three ways: wholesale, retail, and contract buying. They followed a simple marketing plan, using outlets in nearby towns and cities, including Metro Manila. For six months of operation, the cost was lowest in fish smoking and highest in fish drying. Gross sales was also lowest in fish smoking, but highest in ‘bagoong’-making. Net profit was lowest in fish smoking and highest in ‘bagoong’-making. Return on investment was 38% in fish smoking, 41% in ‘bagoong’-making, but only 19% in fish drying. More than one-half of the processors earned incomes of P20,000–35,000 a month, one-fifth earned less, but one-fourth earned more.

    Fish processors in Region III in 1992 were on average 46 years old; nearly 80% were 26–55 years old and only two were younger than 26 years. There were more women than men in fish processing, particularly in Bataan, and about 93% were married. The respondents had formal education, but 60% did not go beyond elementary school. The respondents had considerable experience in fish processing, 60% of them having been in the business for 5–20 years, and 19% of them for even longer. Many reported household expenditures of P1,000–3,000 a month, but some also as high as P6,000–7,000 a month. The processors owned household appliances and furniture, and a few owned motorized boats.

    The Department of Agriculture provided extension services and credit to fish processors in Region III. Services included technical assistance, direct consultation, field visits, lectures, demonstrations, training, seminar, and preparation of feasibility study when availing of loans. Most fish processors in Bulacan considered extension services important, but most of those in Nueva Ecija were indifferent to extension services, apparently because they already had the needed knowledge and skills. In Pampanga, the older processors and those with greater investment considered extension services very important. In Zambales, processors with more experience required less extension services. In Bataan, gender, education level, investment, civil status, and income significantly influenced the processors’ assessment of the importance of extension services and the extent of their participation in the government’s extension program. Women considered it very important to avail of extension services, especially those who were married and those with little formal education.
  • 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

    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.

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