Now showing items 1-20 of 237

    • Book

      First annual report of the Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC) for the fiscal year ending December 31, 1973 

      Southeast Asian Fisheries Development Center, Aquaculture Department - 1974 - Aquaculture Department, Southeast Asian Fisheries Development Center
      An illustrated account is presented, covering background (establishment of the department), plan of operation (functions; activities), project site development (Leganes Station, Tigbauan Station, construction of buildings, infrastructure development), research (prawn fry stocking, collection of prawn spawners, research staffing, research tie-up with Mindanao State University, Japanese fisheries experts), equipment (preparation of the list of Japanese donated equipment), organization of the department, funding.
    • Book

      Annual report 1974 

      Southeast Asian Fisheries Development Center, Aquaculture Department - 1975 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The 1974 report describes the development of project sites at Tigbauan and Leganes, where new ponds and labs have been established. The facilities of these labs include covered and open ponds, wet and field labs, a food preparation building, as well as dormitories and housing units. A substation is now operating at Nueva Valencia, investigating the life cycle of tiger prawn, Penaeus monodon, and 5 further substations also exist. Organisational aspects are described, covering scientific staff, equipment, funding etc. The Department s activities are described in detail; these are mainly concerned with shellfish culture and the associated problems. Notes are included on the First Aquaculture Research Conference (April 1974)and 7th SEAFDEC Council Meeting (Dec 1974). Finally, the new and continuing research projects to be conducted during 1975 are listed.
    • Book

      Annual report 1975 

      Southeast Asian Fisheries Development Center, Aquaculture Department - 1976 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Article

      Land-based mass production of prawn (Penaeus monodon Fabricius) spawners 

      JH Primavera - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The first spawnings were obtained 12 days after ablation with 4 spawners yielding 784,000 eggs and a harvest of 250,000 P10 fry. Survival of females after 1 month was approximately 30%. Mortalities were mostly due to handling stress during the regular ovarian samplings as well as disease from the accumulated excess feeds on the bottom of the tank. Male survival could not be recorded because of transfers to other tanks and addition of new stocks. Development seemed to peak 3 weeks after ablation. The average number of eggs per ablated spawner was 120,000. However, many of the partially spawned females were removed from the spawning tanks the following day so that remaining eggs released in the next 2 to 3 days could not be recorded. Estimate of the average number of eggs per ablated spawner is 120,000-150,000 in contrast to 500,000 per wild spawner. However, the low production cost more than compensates for the difference. Fry reared in the Wet Laboratory were used for experiments, mostly on feeding. Therefore, survival at harvest is not to be taken as a reflection of stock quality. Although fewer in number, larvae from ablated prawns are as healthy in terms of vigor in swimming and feeding as those from wild females. Most mortalities are due to inability to molt caused by lower water temperatures and inadequate feeding.
    • Article

      Effect of some physico-chemical factors on the survival and growth of Penaeus monodon postlarvae 

      FF Catedral, R Coloso, N Valera, CM Casalmir & AT Quibuyen - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Growth and survival rates of P. monodon postlarvae were examined at different temperatures, salinities, and nitrite and ammonia concentrations, using one feed level. Condition of postlarvae greatly affected the experimental results shown in some instances where very low survival rates were obtained, even for the controls. Results indicated that postlarvae from P10 and up can tolerate salinity changes of 10 to 20 ppt without prior acclimation. Survival generally appears the same for temperatures between 24 and 36°C. It appears that P. monodon postlarvae have higher temperature tolerance. Tolerance of postlarvae at the early postlarval stage is between 30 and 50 ppm of nitrate. They were more tolerant from P10 upwards. Although survival was high in runs containing nitrite, growing appears to have been affected. Postlarvae could tolerate ammonia concentrations up to about 50 ppm. At 100 ppm higher mortality rates were observed. Whether or not there was any permanent effect by nitrate and ammonia at high but apparently tolerable levels is not known.
    • Article

      Effect of different light intensities on the growth of the diatom Chaetoceros calcitrans 

      EC Jereos - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Batch cultures of C. calcitrans were maintained indoors at a temperature range of 21 to 25 C and continuously illuminated by 40-watt daylight fluorescent lights. Cultures were exposed to 5 different intensities from 200 to 25,000 lux. Population counts show that light intensity affects growth and reproduction of the algae cultivated. A comparison of population peak growths showed cultures illuminated by 12,000 lux to have higher cell counts than those exposed to higher or lower light intensities.
    • Book

      Annual report 1976 

      Southeast Asian Fisheries Development Center, Aquaculture Department - 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Article

      The propagation of the mud crab Scylla serrata (F.) de Haan 

      AFD Laviña & AS Buling - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The mud crab Scylla serrata is an important commercial species found in many brackish areas in the Philippines. During spawning and hatching, the berried females migrate to the sea. Seeds for pond stocking are obtained from the wild. Because of the unpredictability of seed supply, there is a need to propagate the species artificially. Thus, spawning, larval rearing, maturation, and rematuration of the species are being studied. The first attempts at hatching S. serrata were successful with rates varying between 75% and 90%. Two out of three trials on larval rearing yielded a few megalops. The first zoeal stages were fed diatoms, rotifers, Artemia salina, and bread yeast. Overfeeding programs were implemented during the critical premolting periods to prevent weakening of the larvae and lessen cannibalism. Larval weakening during the premolt makes them susceptible to attacks by fungi like Lagenidium and ciliates like Vorticella. S. serrata larvae survived salinity levels as low as 15 ppt until the 14th day of rearing. Other larvae were able to survive in salinities of 30-32 ppt for 8 to 13 days. Zoeal molting was hastened by lowering the salinity to 25-27 ppt. Artificial broodstocking of juveniles and adult crabs has been made possible using a simple refuge system made of three-compartmented hollow blocks. This system has been helpful in minimizing fighting among crabs. Remarkable growth rates have been observed with feeds like mussel meat and trash fish. Average growth increments of 11 mm carapace length and 20 . 35 g body weight have been observed every fortnight. A newly spent spawner could gain additional weight of 22.5 g in only 6 days. Feeding rates of juveniles and adult crabs have been established based on the average body weight from an experiment using mussel meat. Crabs feed more at night. In another experiment, eyestalk ablation was found to be effective in inducing growth and mating. Aside from hastening the molting process, copulation is induced even among the small crabs (average carapace length = 55 mm). Natural mating lasts about 26 hr. A copulation which lasted for seven days with a break in between was observed.
    • Article

      Notes on ovarian rematuration of ablated sugpo (prawn) Penaeus monodon Fabricius 

      JH Primavera & E Borlongan - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      To what extent spent P. monodon females can remature and spawn successive broods is an important question in terms of recycling spawners in a commercially viable operation. Corollary to this is the quantity and quality of fry from rematured females in comparison to those from first spawning. Of 347 experimental females, only 10.1% had a second spawning, and 1.4% a third spawning. To a large degree the low rate of rematuration is due to high spawner mortality - average survival period after spawning was only 6 days in a sample of 176 spawners. It took an average of 23 days after ablation for a prawn with undeveloped ovaries to mature and spawn. An ablated female may have another spawning in as little as 5 days after the previous one. Average fecundity was 180,000 eggs per second spawning, and 140,000 eggs per third spawning. The average number of eggs from first spawning ablated females was 110-120,000. Hatching rate was lower for rematuration: 44% for second spawnings, and 35% for third spawnings, as compared to 64% for first maturation.
    • Article

      Methods of harvesting and preservation of the diatom Chaetoceros calcitrans 

      OM Millamena, EC Jereos & IR Gorriceta - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Diatom culture and larval feeding experiments were conducted to test the viability and acceptability of preserved algal concentrates. C. calcitrans is characterised by the presence of setae which keep them suspended in cultures and make autoflocculation very difficult. Flocculation was induced by the addition of a floc-forming chemical. Using the optimum conditions, it was possible to harvest the algae within 1-h settling time and with about 84% recovery. The viability of frozen Chaetoceros was determined by actual cell reproduction. Preliminary feeding experiments showed that Chaetoceros can be successfully used as a substitute for fresh diatoms as feed for Penaeus monodon larvae. Simple freezing techniques, with or without the use of protectants has been found convenient for preserving algal concentrates in small volumes for both feeding and culture purposes.
    • Article

      A suctorean parasite of Penaeus monodon larvae 

      RQ Gacutan, AT Llobrera, CB Santiago, PJ Gutierrez & G Lio - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      A new disease caused by a suctorean has been observed in tank-spawned and reared P. monodon larvae. Identification of the etiologic agent pointed to Ephelota gemmipara R. Hertwig, a species commonly found to inhabit hydroid colonies.
    • Article

      Identification and culture of common diatoms as possible feed for Penaeus monodon 

      T Pimoljinda - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Diatoms were collected from Buyuan Bay, and from the hatchery tanks at Tigbauan, to determine the commonly occurring species, the feasibility of culturing these species, and the potential of these selected species as food for larval P. monodon. The commonly occurring diatoms were identified as Chaetoceros calcitrans, Navicula grimmei, Nitzchia seriata, Nitzchia closterium and Amphiprora sp. These diatoms were isolated and unialgal cultures prepared. Protein content analysis using the micro-Kjildahl method gave the following result: C. calcitrans, 11 . 78%; Nitzchia seriata, 25%; Nitzchia closterium, 30 . 5%; Navicula grimmei, 9 . 06% and Amphiprora sp. 8 . 96%.

      Feeding experiments were conducted to determine acceptability of the different diatom species and percentage survival of larval stages Z1 - M2. Larvae were placed in 4-l capacity plastic containers with a stocking density of 10/l. The results of several feeding trials using the different mass-produced diatoms are summarized.

      From the data gathered, C. calcitrans appears to be the most promising candidate as feed for zoea and mysis stages of P. monodon. The average percentage survival of C. calcitrans was 63 . 76% for the 3 trials, and as high as 82 . 22% in the third trial. Comparatively high percentage survival of larvae was also recorded when Nitzchia seriata (48 . 17%) and Nitzchia closterium (67 . 6%) were given as feed, while both Amphiprora sp. and Navicula grimmei gave 0% survival. The poor results with Amphiprora sp. and Navicula grimmei may be due to their low protein content (8 . 96% and 9 . 06%, respectively) and the inability of the larvae to ingest them. Navicula and Amphiprora were observed to cling to the appendages of the larvae and to settle down in the medium making them unavailable to the larvae. Low survival was also noted when frozen C. calcitrans was used (14 . 25%). This may be due partly to the effect of the floculating agent (ALSO4.25 g/l) used in concentrating the diatoms.

      When protein contents of C. calcitrans, N. seriata and N. closterium are compared, the 2 Nitzchia species have relatively higher protein contents than C. calcitrans and, therefore, could be the more desirable feed candidates. However, few feeding trials were made using Nitzchia so that additional investigations will have to be done on this aspect.
    • Article

      Effect of nitrite, ammonia, and temperature on P. monodon larvae 

      FF Catedral, DD Gerochi, AT Quibuyen & CM Casalmir - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      P. monodon larvae were studied for the effects of temperature, ammonia, and nitrite on survival. Toxicity levels of nitrite were found to vary with larval stage. Larvae could tolerate ammonia up to about 10 ppm, with the effect more clearly shown by the zoea stage. Survival and growth were not significantly affected by temperature, although moulting was enhanced at temperatures higher than 29°C. Larvae of P. monodon have lower tolerance toward nitrite and ammonia compared to postlarvae. Although high survival was obtained at low levels of nitrite and ammonia, it is still necessary to know their effects on metabolism, in order to examine possible biochemical parameters for diagnosing sublethal toxicity or stress.
    • Article

      Notes on the induced maturation and spawning in four-month-old Penaeus monodon Fabricius by eyestalk ablation 

      JH Primavera & E Borlongan - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The ablation technique consisted of making an incision across the eyeball to allow free flow of fluids while holding the prawn under water, squeezing the eyeball contents outwards, and pinching hard the eyestalk tissue. The cut area heals completely in about a week; no application of antibiotics is necessary. Spent spawners were tagged with thin brass rings (Rodriguez, 1976) around the unablated eyestalk for a separate experiment on rematuration. Two spawning yielding approximately 277,000 eggs were obtained three weeks after ablation, followed four days later by two more spawnings with 160,000 eggs; all four spawners weighed more than 100 g. With a hatching rate of 98% and 78% for the first and second batch, respectively, the spawnings produced viable nauplii. Water temperatures as low as 23°C due to a delayed cold spell in March depressed molting; weakened larvae had to be discharged at the mysis stage. Although ovarian development continued, no further spawnings were obtained due mainly to the onset of bacterial and fungal disease. Infection is initiated in injured portions of the exoskeleton, sometimes penetrating right through the muscles to the ovarian tissues. The non-flowthrough conditions and mussel meat feeding led to fouling of the culture water resulting in consecutive mortalities caused by disease. Female P.monodon held in maturation pens were ablated at the age of 15 months (Santiago, et al., 1976); they averaged only 16 g body weight after four months growth in ponds. In another experiment, pond-reared P.monodon females ranging from 50 to 80 g were ablated at approximately seven months (Aquacop, 1977). The present results show a minimum age of four months from postlarve that P.monodon is capable of ovarian development and spawning upon ablation. However, maturation is probably affected by size as well as age - the four-month old females weighed an average of 100 g in contrast to the smaller animals in the earlier experiments.
    • Article

      Notes on the external sex characters of Chanos chanos Forskal spawners 

      H Chaudhuri, J Juario, Samson R. & R Mateo - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      In this study, the authors did not find any visible differences between the sexes with reference to external features such as coloration, shape of head, snout and operculum, presence of tubercles or nasal pores, length, size and shape as well as any roughness in the various fins. However, the anal region of the mature milkfish exhibits discernible anatomical differences in the male and female. In the males, there are 2 main openings visible externally. These are the anterior anus and the posterior urogenital opening at the tip of the urogenital papilla. Internally, the vasa deferentia (male genital ducts) from the testes join into a common duct about 5-10 mm from the urogenital pore. The urinary pore opens into this common duct from the dorsal side. In addition, there are 2 small pores situated on each side of the base of the urogenital papilla opening ventrally into the coelom. In the females, there are 3 main openings in the anal region instead of 2 as found in the males. The anteriormost opening is the anus followed by the genital pore. The third opening is the urinary pore which is posterior to the genital pore located at the tip of the urogenital papilla.
    • Article

      Bioenergetics of the freshwater prosobranch Idiopoma angularis Muller in Laguna de Bay 

      EA Baluyut - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      This study was made as an attempt to investigate some of the ecological aspects of the freshwater snail Idiopoma angularis Muller in a modern framework of energy flow and mathematical models. It offers the first investigation of respiration (as related to temperature and body size), production (growth), and excretion in the prosobranch I. angularis in Laguna Lake.
    • Article

      Effect of temperature on the oxygen consumption of Penaeus monodon postlarvae 

      FF Catedral & R Sayson - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Extended abstract only.
    • Article

      Biology and farming of the green mussel Mytilus smaragdinus 

      WG Yap, C Orano & M Tabbu - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Biological investigations were carried out in Sapian Bay, Capiz from November 1975 to December 1976 with samplings conducted fortnightly. Histological studies on the gonad reveal a high percentage of ripe and spent females during the month of April and May, and ripe to near ripe during November to December. However, larval counts were highest on February 25, 1976 with 253 mytilid larvae per haul compared to 0-79 per haul during all other months. The high larval count was followed by the highest spat settlement during the next sampling period two weeks later, with the spat collector set in the water during the February 25 sampling. The four materials tested, blue polypropylene fiber rope, black polypropylene fiber, and coir rope, all had their highest spat counts during this period with an average of 471 spats per standard 10 cm rope piece. The range during the other time periods is 2-283 spats. Of the 4 materials tested, the black fibrillated polypropylene film had the highest larval counts in 15 out of a total of 25 sampling periods. The blue rope was the poorest spat collector. Coconut husk was tested later on and it proved to have a very high catchability, with spats completely enveloping the husk surface. Growth monitored from one cohort in Sapian Bay averaged 10 mm per month. 50-60 mm is considered marketable size. Trial growth experiments with transplanted mussels were also conducted at Igang Bay in Guimaras Island, Makato River in Aklan, and a milkfish pond in Leganes, Iloilo. Survival in Igang was less than 50% after the second week, and the condition of the surviving mussels can be described only as watery with the mantle completely transparent. Mortality was minimal in Makato but the growth rate was only 30% that of Sapian Bay. The pond experiments were terminated due to severe crab predation.
    • Article

      Salinity preference of the milkfish Chanos chanos Forskal 

      JV Juario & C Dueñas - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Extended abstract only.
    • Article

      Ecology and life history of penaeid shrimps 

      H Motoh, N Solis & E Caligdong - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Fourteen species of penaeid shrimps with commercial value in Batan Bay and Tigbauan-Guimbal waters were identified as follows: Penaeus monodon, P. semisulcatus, P. japonicus, Metapenaeus ensis, M. burkenroadi, M. endeavouri, Metapenaeopsis palmensis, M. stridulans, Trachypenaeus fulvus, and Parapenaeus longipes. Among the 14 penaeids, P. semisulcatus, M. ensis and M. palmensis were found to be the dominant species within each genus. There are seven existing fishing gears for shrimping in the Batan Bay and Tigbauan-Guimbal waters: fish corrals, lift net, filter net, gill net, skimming net, baby trawler and commercial trawler. In general, female penaeids are larger than males. The largest P. monodon female measured was 81 mm in carapace length with 23 g in body weight. The largest male measuring 59 mm in carapace length with 119 g of body weight was caught in Batan Bay. Judging from spermatozoa occurrence on both sexes of P. monodon, the biological minimum size for male is 37 mm in carapace length and 49 mm for female. A total of 133 Penaeus postlarvae obtained from the offshore were identified by comparison with those reared in the laboratory. The postlarvae of P. japonicus-latisulcatus complex were quite dominant (60.2%), followed by P. semisulcatus (18.0%), and P. merguiensis-indicus complex (17.3%). The number of P. monodon postlarvae was relatively small (4.5%). The modal carapace length of P. monodon postlarvae from the offshore was 1.3 mm with three or four dorsal and no ventral spines on the rostrum, while P. monodon fry from the shoreline had 2.3 mm with five or six dorsal and one or two ventral spines.