Recent Submissions

  • Book chapter

    Fish catch and fisher incomes before and after installation of artificial reefs in Panguil Bay, northern Mindanao 

    HP Moncay & LP Cablo - In TU Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Two artificial reef complexes (10 modules) were deployed in Panguil Bay in 1990. The effect of the ARs on the fish catch and fisher incomes was studied from March 1993 to April 1994 in Purok 3, 4, 6, and 7 in San Antonio, Ozamis City and in Poblacion 1 and 4 in Clarin, Misamis Occidental. Clarin‘s 40 full-time fisher respondents had 50 outrigger boats, all without engines, and used 181 fishing gears, 93% of them simple or multiple hand lines. San Antonio‘s 80 full-time fisher respondents had 87 non-motor boats and 44 motor boats and used 489 fishing gears, 86% of them bottom-set gill nets. The fishers worked an average of 19 days a month and four hours a day. The fishing grounds were mostly between 3 and 3.5 km from shore, and the gears were operated in waters about 50 m deep. Of about 17,000 kg of fish harvested in Clarin and San Antonio over one year, 33% came from bottom-set gill nets, 32% from bottom-set long lines, and 28% from multiple hand lines. The catch included a great variety of fishes, plus shrimps and cuttlefish; threadfins made up 13% of the total volume by weight, slipmouths 10%, and sardines 7%. The catch ranged from 2,382 kg valued at P75,862 in Purok 3 to 3,212 kg worth P97,303 in Poblacion 1, but in Purok 7, the catch was 2,965 kg worth P123,195. The average annual revenues of fishers was P24,191 in San Antonio and P11,472 in Clarin, corresponding to monthly earnings of P2,016 and P956, respectively. The revenues and net incomes were low, but the returns on investment were high (78–300%). The fishing boat, with or without engine and gas, was the major expense incurred by the fishers. Between 1989 and 1993–94, the volume of fish catch increased two-fold in San Antonio and four-fold in Clarin. The average annual income of fishers in the six villages increased by 10–60% after the ARs, and the average annual expenses also increased by 5–30%. In 1993-94, the computed return on investment was 105% in San Antonio and 274% in Clarin, higher than in 1989.
  • Book chapter

    The squid fishery in Carigara Bay, Samar: catch of Photololigo duvaucelii by squid jigs and Sepioteuthis lessoniana by hanging squid pot 

    JO Dickson & BR Ricafrente - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    The squid fishery in Carigara Bay used the following gears: hanging squid pots, squid jigs, drive-in net, and spear by slingshot. Hanging squid pot operations were concentrated in the municipal waters of Capoocan and Carigara and targeted Sepioteuthis lessoniana. During the one-week survey in Carigara Bay, 705 hanging squid pots with markers were found offshore of barangays Culasian, Pinamopoan, Cabul-an and Talarian, all in Capoocan town. Other operators in Carigara, Babatngon, Barugo, and San Miguel towns hung their squid pots from fish shelters (arong) offshore of Carigara and Capoocan towns. Test fishing operations were conducted in Carigara Bay from January to December 1992 using the hanging squid pot, squid jigs, and a squid cast net. A 16 hp motorized boat F/B Ellah Meh was used during the fishing operations. A total of 162 days test fishing with 15 hanging squid pots yielded 125.7 kg of the longfin squid Sepioteuthis 1essoniana. Sixty nights of fishing with the ordinary squid jig yielded 97 kg of Indian squid Photololigo duvaucelii. Two test fishing operations with the squid cast net yielded no squid at all. The S. lessoniana (75-500 g body weight) caught by pots were larger than the P. duvaucelii (7-270 g) caught by jigs.
  • Book chapter

    Improved production of mud crabs Scylla serrata in marine pens with used tires and bamboo tubes as shelters 

    MC Basaya - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    One serious problem in mud crab farming systems is cannibalism and low survival, but this can been offset by provision of shelters. Two types of shelters were tested on mud crabs grown in bamboo pens set in a mangrove area in Tiniguiban Cove in Puerto Princesa. Six pens, each 3 m x 3 m in area, were built side by side (the whole array 9 m x 6 m in area). Two pens were provided bamboo tubes, two had used tires, and two had both shelter types. The bamboo tubes were about 46 cm long and 13 cm in diameter, open on both ends, and each with a node retained as partition. The bamboo tubes were laid in one layer at the middle of the pens, 48 tubes in each of the two pens. The used tires were 50 cm in diameter, placed 20 cm apart in one layer in the middle of the pens, 12 tires in each of two pens. In the two pens that had both shelter types, half the number of bamboo tubes and used tires were laid out. All shelters were tied and did not move off the bottom. Juvenile crabs of 46 g body weight were stocked at 63/pen or 7/m2. The crabs were fed chopped trash fish at 5% of body weight daily at 0800 h and 1600 h. Mud crabs in the pens with bamboo tubes as shelters had the best survival (79%), weight gain (81 g), net production (4.5 kg/pen), and feed conversion ratio (4.9), as well as net income (P544,202/ha-yr) and return on investment (48%). The results clearly indicated that bamboo tubes were better shelter for juvenile mud crabs than used tires. Bamboo tubes were presumably more familiar to mud crabs reared in bamboo pens. Having node partitions in the middle, the bamboo tubes had smaller and safer hiding places. These shelters effectively reduced crowding, aggression, and cannibalism, and thus increased the survival and growth of mud crabs. The used tires evidently did not provide a good shelter configuration nor sufficient protection for mud crabs in bamboo pens.
  • 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

    Giant squid Thysanoteuthis rhombus caught by jigs in Calauag Bay, southeastern Luzon 

    JO Dickson & RV Ramiscal - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    Test fishing for the giant squid Thysanoteuthis rhombus using large jigs was conducted in selected areas around Alabat Island, Quezon Province from May 1991 to October 1992. A total of 92 fishing days and 425.3 fishing hours were successfully completed and 1,650 jigs were set. The total catch was 82 giant squids of total weight 412 kg. Catch per unit effort was on average 0.02 kg/jig-hour or 5 squids/100 jigs, but higher from July to September. Capture of the giant squid by jigs was very seasonal, only from June to October. During these months, fish aggregating shelters were installed to catch pelagic fishes, and these shelters may have attracted the giant squid to Calauag Bay. The sample of 82 giant squids adds considerable information to the biology of this species in Philippine waters. The smallest specimen, caught in August 1991, was 23 cm in mantle length and 750 g in weight. The largest specimen, caught in September 1992, was a male 69 cm in mantle length and 10.3 kg in weight. Of the 66 specimens examined, 31 were males and 35 were females. About 52% of the specimens were sexually mature, 30% were maturing, and the rest were immature. Of the 61 stomachs dissected, 20 were empty, six were full or 3/4 full, and the rest were in between. The giant squid was a fish eater, almost all stomachs containing fish bones, spines, scales, or digested fish meat.
  • 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

    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

    Collection of the orange-spotted grouper Epinephelus coioides from Tinagong Dagat and Sapian Bay in northern Panay 

    NB Solis - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of Agriculture
    In Capiz, northern Panay, grouper catches by hand picking, hook and line, shelters, and fish corral were low throughout the year, on average 1-3 fish from each fishing operation, but higher in Tinagong Dagat than in Sapian Bay. Epinephelus coioides was the most common of the three grouper species collected; E. quoyanus and E. malabaricus were not numerous. The 882 specimens of E. coioides from Tinagong Dagat measured from 3.6 to 39 cm in standard length; the 250 E. coioides from Sapian Bay were between 1.7 and 31.2 cm SL. The size distribution showed a modal length of about 17 cm SL (21% of the fish) in Tinagong Dagat, and 11 cm (26%) in Sapian Bay. Small juveniles 2–8 cm were collected from Tinagong Dagat in January-April 1993, but not in Jan-Apr 1994. Such small juveniles were also collected from Sapian Bay in January and in April–August 1993. Groupers 9–23 cm occurred year round, but the 9–15 cm group was more abundant from January to June. At both sites, groupers >30 cm could hardly be found. Both grouper habitats experienced wide ranges of water temperature, salinity, and dissolved oxygen during the year.
  • 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

    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

    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

    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

    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.
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    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.
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    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.
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    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.

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