The development of a shrimp (Penaeus monodon) production system integrated with livestock was undertaken at the Sycip Plantation Inc., Negros Oriental, Philippines, as a result of crop diversification efforts in the province. Heavy organic manuring of brackishwater shrimp ponds strongly stimulated the production of lablab in the initial stages of pond preparation. Observations suggest that the problem of deteriorating water quality in the later stage of culture due to prawn burrowing/feeding activities, was exacerbated by constant addition of manures. Plankton analysis of pond water indicated that this was a result of excessive nanno- and picoplankton blooms. A highly significant correlation (P < .001) between plankton (cell size < 5 microns) count and BOD was obtained. An alternative system using "kitchen ponds" stocked with artemia provided a suitable source of food for shrimp growth. Daily additions of manure (100 kg dry weight/ha/day) produced an average 40 kg of mixed artemia and lablab protein each day during a three-month study period. Analysis of input:output ratios for the kitchen pond showed a net loss in organic matter and net gain in nitrogen yields during the conditioning period. Conditioned ponds had a net gain in both organic matter and nitrogen yields. An area ratio of 1:5 for kitchen pond to shrimp grow-out enabled production at 700-1,000 kg/ha/crop at 30,000 pieces/ha stocking density, 60-70% survival and grow-out period of 120 days. Significant reductions in feeding costs were obtained.

Milkfish,Chanos chanos fingerlings transported by boat (petuya) for seven to eight hours were observed for stress-inducing factors during transport, daily for 10 days after stocking in pens in Laguna Lake, Philippines. Handling, hauling, and crowding of fish contributed to stressful conditions. Likewise, the transport procedure of the clising the water entry hole at the bottom of the boat to block water exchange was associated with decreased dissolved oxygen and increase tubidity, with respective values of 2.4 mg/l and 79 Formalin Turbidity Units when water change was possible. In addition , marked and abrupy fluctuations in salinity from 15 to 30 ppt then 0 ppt within 1 to 3 hr were observed during transport. Although moralities during transport were minimal, subseqeunt deaths after stocking in pens mounted to not less than 2.4%. Reddish snout, scale loss and hemorrhagic areas along the lateral body surface wwere observed. Bacterial counts of water increased significantly during trasnport when water exchange was stopped. Kidney and skin/muscle specimens yielded significantly higher bacterial counts on days 2, 3, 5 and 8 poststocking predominated by Aeromonas hydrophila biovar hydrophila and two species of gram-negative bacilli phenotypically resembling Pseudomonas sp.

The development of body parts for swimming and feeding in Siganus guttatus larvae was studied in samples reared in the laboratory at temperatures of 27.3-30 degree C. From the observations, the larval stage of S. guttatus may be divided into three phases: (1) inactive swimming and feeding by swallowing (to about 4-5 mm TL); (2) the transitional phase (to about 7-8 mm TL); and active swimming and feeding (8 mm TL and beyond). A change in feeding habits may be expected in S. guttatus larvae at sizes 7-8 mm TL as shown by this study.

This paper presents research attempts to develop a suitable artificial diet for shrimp larvae with locally-available materials. Larval rearing experiments using finely ground Acetes tissues conducted under various climatic conditions and hatchery systems were completed. In the dry season, larvae in outdoor tanks fed dry Acetes had the highest survival rate (68%) compared to larvae fed Chaetoceros (48%) or fresh Acetes (39%). In contrast, larvae from an indoor hatchery reared with Chaetoceros had higher survival rate (52%) than those fed with Acetes (35%) and fresh Acetes (24%). During rainy months, the survival of larvae reared with Skeletonema , dry and fresh Acetes in outdoor tanks was 72%, 52% and 38% and in indoor tanks 62%, 40% and 23%, respectively.

During a red tide episode caused by Pyrodinium bahamense var. compressa in Western Samar, Philippines in 1983, those who were taken ill after ingesting the green mussel, Perna viridis , resorted to drinking coconut milk (gata , Pilipino) with brown sugar or unpurified sugar lumps (tagapulot , Pilipino) as a temporary palliative, pending medical attention. Many victims felt relief after the drink. Crude toxins (CT) were extracted from P. viridis exposed to Pyrodinium using 0.1 N HCl and reacted with either or both 5% coconut milk (CM) and 5% brown sugar (BS) for an hour. The CT, CM, BS, CT + CM, CT + BS, and CT + CM + BS were assayed in duplicates for saxitoxin using the standard mouse toxicity test. CT with initial toxicity of 2,114 MU/100 g meat was substantially detoxified after a one-hour reaction. In CT + CM, the toxicity was 664 MU/100 g; in combined CT + CM + BS the toxicity was 1,005 MU/100 g. In medium- (436-563 MU/100 g) and low-toxicity extracts (160-231 MU/100 g) no deaths in mice were recorded within one hour of injection.

Among the economically important bivalves, the slipper oyster (Crassostrea iredalei) and green mussel (Perna viridis) are predominantly being farmed in the Philippines. Oyster and mussel farms in the Western Visayas region have increased because of the need for supplementary sources of income brought about by the dwindling catch of small-scale fishermen. Socio-demographic and costs and returns data were gathered from 175 oyster and mussel farmers using a combination of rapid rural appraisal techniques and a pre-tested questionnaire. Oyster and mussel farms, less than 1000 m², were located among fish capture devices in rivers and bays. The oyster and mussel farmers belong to the marginalized sector of society with about 30% of total household income derived from oyster and mussel farming. Problems encountered by oyster and mussel farmers included poaching, mortality due to siltation or sedimentation and pond effluents, no spat, lack of financing, and lack of buyers. This study recommends that oyster and mussel farmers form cooperatives to effectively market their produce and avail of financing, and research on the non-occurrence of spat.

Oreochromis niloticus fingerlings were stocked at densities of 50, 100, 150 and 200 fish/m super(2) in fixed net cages in Laguna Lake, Philippines. These were reared without supplemental feed on 1 April-30 July 1980, 5 August-3 December 1980, and 19 December 1980-19 April 1981. Water temperature, dissolved oxygen, chloride level and pH for the three periods were measured outside the net cages. Growth rates were highest at 50 and 100 fish/m super(2) reared between April and July when phytoplankton biomass was high with a peak production observed in June (65.5 g/m super(2)), and zooplankton biomass ranged from 9.3 to 32.68 g/m super(2). Under these conditions, fish initially weighing 1.6-1.7 g grew to a marketable size of 106-124 g in four months. Those stocked at 150 and 200 fish/m super(2) had lower weights but still weighed over 80 g. None of those in the other two rearing periods exceeded 50 g after four months. Survival and fish yield during April-July were also higher than for those reared during the other periods.

Fishpond development in the Philippines is discussed, examining resulting impacts on the mangrove ecosystems. Socio-economical implications and management measures are also considered.

Commercially important penaeids of the closed thelycum group belong to five subgenera of the genus Penaeus — Penaeus, Fenneropenaeus, Marsupenaeus and Melicertus that are almost exclusively Indo-West Pacific and Farfantepenaeus that is predominantly Western Atlantic. Since the ablation of Penaeus duorarum more than a decade ago, the first for any penaeid, around 23 species have been matured in captivity, 17 of them belonging to the closed thelycum subgenera (P. aztecus, P. brasiliensis, P. californiensis, P. duorarum, P. esculentus, P. indicus, P. japonicus, P. kerathurus, P. latisulcatus, P. merguiensis, P. monodon, P. notialis, P. orientalis, P. paulensis, P. penicillatus, P. plebejus, and P. semisulcatus). The complete spectrum of controlled reproduction in penaeids covers maturation, spawning, hatching of eggs into viable larvae, and the production of postlarvae to constitute the next batch of broodstock. The full closing of the cycle has been achieved in at least six closed thelycum species whereas gaps, e.g. inability of mature females to spawn or nonhatching of eggs, remain for the others. Spawners or mature females used in commercial hatcheries and research laboratories are either wild-caught or matured in captivity with human control ranging from nil to a regular closing of the cycle. Wild spawners may be spawned directly after capture and transport or subjected to environmental manipulation, e.g. thermal control to induce or inhibit spawning. Females matured in captivity may come from wild broodstock (adults and subadults caught from estuaries or "sourced" by trawlers from offshore waters) or captive (pond- or tank-reared) broodstock. Introduced or exotic penaeid species must depend on a pond- or tank-reared broodstock whereas indigenous prawns and shrimps may be constituted from wild or captive broodstock. There are three basic approaches employed singly or in combination to induce ovarian maturation in penaeids — endocrine, dietary or nutritional and environmental. Endocrine manipulation has so far been synonymous with unilateral eyestalk ablation, a technique with far-reaching impact on penaeid aquaculture. Closed thelycum penaeids may be classified into those that require ablation in order to mature and those that do not. To a third group belong species that have been experimentally induced to mature with and without ablation. Diets for maturation include fresh and frozen animal sources (mussel, clam, oyster, squid, marine worms, shrimps, fish) and formulated pellets given in any combination. The choice of marine worms and mollusks is based on their high levels of arachidonic, eicosapentaenoic and docosahexaenoic acid, the dominant fatty acids found in mature ovaries and testes. Environmental parameters studied in relation to maturation include light (intensity, quality and photoperiod), temperature, salinity and pH. Although a regular closing of the cycle has been achieved for some, the state-of-the-art for most penaeids is the successful production of larvae and postlarvae from either wild spawners or wild immature/spent females matured/rematured in captivity. The improvement of reproductive performance including larval quality from captive broodstock remains a major area for future research and includes the determination of minimum age and size for maturation. The complete description of the nutritional and environmental requirements for maturation should lead to the development of alternatives to ablation such as photoperiod manipulation or the use of reproductive hormones. The present focus on characterizing the physicochemical and dietary requirements for maturation should be extended to other phases of reproduction: mating, spawning, fertilization and hatching. Studies on biology (molting, mating, fertilization including the cortical reaction) and biochemistry (maturation stages) provide baseline information for designing maturation tanks and formulating broodstock pellets. Investigations of wild stocks complement laboratory studies in elucidating the interrelationships among molting, mating, maturation and spawning. Manual spermatophore transfer is being developed to solve the problem of nonmating in closed (and open) thelycum species. This technique will also be useful in future hybridization work, together with in vitro fertilization.

Unialgal cultures of Oscillatoria quadripunctulata, Chroococcus dispersus, Navicula notha, Euglena elongata, and Chlorella ellipsoidea were fed to tilapia fry for 30 days. Mean weights and survival rates of the fry were highest when given Navicula (105.6 mg, 86%) and Chroococcus (89.1 mg, 90%). Oscillatoria, a filamentous cyanophyte, showed limited acceptability to tilapia fry, possibly because of its larger size in comparison with Chroococcus. Fry fed Chlorella and Euglena did not survive at all. C¹⁴-labeled algae of the above species were fed to tilapia fry of varying ages. Assimilation rates per fry after 24 hours of feeding with a suitable algal species increased with the age of the fry. Moreover, the same trend as in the growth and survival experiments was observed, i.e., the highest assimilation rates were obtained in 40-day old tilapia fry given Navicula and Chroococcus as natural feeds. On the other hand, negligible amounts of the other three algal species tested were assimilated by tilapia fry. The above results were explained in terms of the enzyme secretion of tilapias. There seemed to be no transition stage in the feeding habit of both fry and adult tilapia. The acceptability of plant matter in the diet of even the early larval stages was demonstrated.