This document presents the recommended methodology, nominal projections and partial costs and returns, for extensive prawn culture at two production objectives, and semi-intensive culture with costs and returns breakdown for three production targets. Intensive prawn culture procedures are not discussed. Extensive Prawn Culture System I projects a production yield of about 110 to 160 kg/ha/crop or more in four months and survival rate of from 65 to 70%. The extensive Prawn Culture System II aims for a production rate of about 230 kg/ha/crop in four months at about 70% survival with expected average body weight of about 25 grams. The procedures indicated have been verified and are now widely practiced. Production targets under the Semi-intensive Prawn Culture System I range from 350 to 500 kg/ha in four months at survival rate of about 70 to 75% and expected average size at harvest of about 28 to 30 pcs/kg. This method has been confirmed at different collaborative sites using the modified SEAFDEC diet developed by the Feed Development staff of the SEAFDEC Aquaculture Department.

The window-pane shell Placuna placenta or 'kapis' has great economic importance in the Philippines. The translucent shell is used in the manufacture of lampshades and other shellcraft items exported to Europe, USA and Japan. Due to its high demand, excessive and uncontrolled gathering of kapis has been noted over the past years. Its possible depletion has been a concern; thus, a nationwide survey on the status of the fishery was conducted in 1993. There are 27 kapis beds in the Philippines, six of which are considered the major sources of kapis shells. Kapis shells are gathered by (1) handpicking (in shallow areas); (2) compressor diving (in deeper areas); and (3) dredging. Because of open access to the fishery, anybody can exploit the resource. Kapis stocks are declining in most beds, while in others they are already low as a result of excessive gathering, pollution, siltation, and destructive methods of fishing such as trawling. To prevent further depletion, establishment of sanctuaries, bans on trawling and other destructive means of fishing, strict enforcement of existing regulations, community-based fishery management, and further research on seed production, restocking, and transplantation are recommended.

Fish meal is the major protein source in shrimp and fish diets but its continuous use would make it scarce and expensive. There are, however, potential substitutes like soybean or leaf meals. Papaya or camote leaf meals have not been tested as partial replacement for fish meal in diets for tiger shrimp. Thus, two feeding trials were made to test diets with leaf meals against a control shrimp diet. Both experiments used 50 mg shrimp stocked at 10 per 40 liters of sea water following standard water management. Trial 1 had diets containing either 17% soaked or unsoaked camote leaf meal or 16% papaya leaf meal. Results indicated that weight gain, specific growth rate and feed conversion ratio of the unsoaked papaya were similar to the control, higher than the unsoaked camote, but not significantly different (α= 0.05) from the soaked camote and papaya groups. Survival was not significantly different among treatments. Trial 2 used the best diet from Trial 1 - unsoaked papaya leaf meal - at 16%, 19% or 22% of the diet. The weight gain (1846%) of the shrimp fed 16% papaya leaf meal was not significantly different (α= 0.05) from the control 2034% but higher than the 22% group (1535%). Therefore, papaya leaf meal can partially replace (10%) animal protein in shrimp diets and serve as a source of exogenous proteolytic enzyme. However, its efficacy in culturing shrimp in ponds must be tested.

Adult Oreochromis niloticus were mass spawned in concrete tanks. The one-month old progenies (F₁) were exposed for two months to a mixture of 0.01 mg L⁻¹ Hg, 0.1 mg L⁻¹ Cd and 1.0 mg L⁻¹ Zn. The survivors were grown to sexual maturity in a natural environment (lake). The fish were spawned and the progenies (F₂) of the exposed F₁ (EF₁) were exposed to another mixture of the three metals: 3.0 mg L⁻¹ Zn, 0.30 mg L⁻¹ Cd and 0.01 mg L⁻¹ Hg, both in a static and static-renewal system. Another group of F₂ from unexposed F₁ (UF₁) received the same treatment. Results showed that in both exposure systems, survival of the F₂ of EF₁ was significantly higher (P<0.05) than those from UF₁. The medial lethal time (LT₅₀) of the F₂'s were estimated from the time-response curve following regression analysis: 5.16 days (F₂ of UF₁) and 9.03 days (F₂ of EF₁) in the static exposure experiment; 3.34 days (F₂ of UF₁) and 5.52 days (F₂ of EF₁) in the static-renewal run. Exposure of the parental stock resulted in the culling out of individuals which were more susceptible to the heavy metals. The more resistant members of the population (survivors) which have the ability to adapt to the toxicants were able to pass on the resistance to their offspring. The results are supported by other studies in the field which demonstrate high resistance in populations of organisms living in contaminated sites.

The optimum protein-to-energy (P/E) ratio for juvenile sea bass (body weight, 1.34 ± 0.01 g) was determined using practical diets in a 3 × 3 factorial experiment. Three protein levels (35, 42.5 or 50%) and three lipid levels (5, 10 or 15%) at a fixed carbohydrate level of 20% were tested. P/E ratios of the diets ranged from 104 to 157 mg protein/kcal. The fish were reared for 54 days in 60-liter flow-through tanks with seawater at 32 p.p.t. and 29 °C. Fish fed the diet containing 50% protein and 15% lipid (P/E ratio of 125 mg/kcal) showed the highest weight gain and specific growth rate. Those fed the diet with 42.5% protein and 10% lipid (P/E ratio of 128 mg/kcal) showed comparable growth rate and significantly better condition factor, protein efficiency ratio and apparent protein retention. Fish given diets containing 35% protein showed the poorest growth. Those fed diets with 5% lipid regardless of the protein content showed abnormal reddening of the fins, indicating essential fatty acid deficiency. Body fat increased with fat content of the diet and was inversely related to moisture. Fish given the diet containing 35% protein and 5% fat had the lowest body fat content and the highest ash and water content. The diet containing 42.5% protein and 10% lipid with P/E ratio of 128 mg protein/kcal was found to be optimum for juvenile seabass under the experimental conditions used in the study.

Penaeus monodon stocked in ponds at 8000/ha were fed four types of farm-made feeds starting on day 16 of a 4-month culture period. The feeds were golden apple snail alone or in combination with cooked cassava or maize, or maize only. Mixed feeds resulted in significantly higher production, growth, and better size-frequency distribution of shrimp. Survival (88–99%) was not significantly different among the treatments. Maize alone or snails alone were inadequate. Presumably, the high amount of carbohydrate in cassava (92%) or maize (87%) provided the needed energy, and the high protein content of golden snail (54%) was available for growth. The fatty acid profile of the golden snail shows that it is a good source of 18:2n-6, 18:3n-3, and 20:5n-3 which are essential fatty acids for P. monodon. The golden snail, with an essential amino acid index (EAAI) of 0.84, is a useful alternative source of protein for tiger shrimp. Feeding shrimps with golden snails and cassava yielded the highest net income (P48797/ha-crop) and return on investment (ROI = 206%) better than feeding with maize alone (net income = P23190/ha-crop; ROI = 120%), an industry practice. If shrimp farmers use golden snails as direct feed or as a feed ingredient, the problem of snail infestation in ricefields may be reduced. Snails will no longer be viewed as pests but rather as a resource which has economic value.

The effect of cortisol and thyroid hormones on the activity of mitochondrion-rich (MR) cells in the yolk-sac membrane of tilapia (Oreochromis mossambicus) embryos and larvae was investigated. MR cells were identified by the fluorescent mitochondrial stain DASPEI. Yolk-sac membranes from 4-day-old embryos in fresh water (FW) were incubated for 24 h in medium supplemented with cortisol, thyroxine (T₄), or triiodothyronine (T₃). Treatment with cortisol at 0.1 μ/ml and higher significantly increased the population of MR cells and the intensity of fluorescence compared with the control, whereas MR cell size was not affected. Treatments with T₄ and T₃ did not affect MR cell density, size, or intensity of fluorescence. Four-day-old embryos in FW were immersed for 10 days in FW supplemented with cortisol, T₄, or T₃. A significant increase in MR cell size was observed starting on day 3 after treatment with 100 μ/ml cortisol. Treatment with lower doses of cortisol produced increases in the cell size on later days. Density of MR cells was significantly increased only on day 9. Treatment with T₄ produced inconsistent results. Treatment with T₃ did not affect MR cell size or density at any time. None of the three hormones affected the intensity of fluorescence of MR cells. The stimulatory activity of cortisol on MR cells in the yolk-sac membrane suggests that cortisol, present in the yolk of tilapia embryos and larvae, may be involved in osmoregulation during the early life stages of fish.

This paper presents the first substantive data on sea turtles in the northeastern Sulu Sea. Working with fishers and government, the Southeast Asian Fisheries Development Center (SEAFDEC FishWorld) documented 109 juvenile and adult sea turtles captured or stranded around Panay and Guimaras Islands, Philippines from 2001 to mid- 2011. These included 65 Green Turtles (Chelonia mydas), 15 Hawksbill Turtles (Eretmochelys imbricata), 24 Olive Ridley Turtles (Lepidochelys olivacea), three Leatherback Turtles (Dermochelys coriacea), and two Loggerhead Turtles (Caretta caretta). From the four fishing villages within 1 km of FishWorld came 29 Green Turtles, eight Olive Ridleys, and one specimen each of the three other species. Approximately 77% of the Green Turtles were caught in nearshore fish corrals, mostly between October and May; whereas, 75% of the Olive Ridley Turtles were caught in offshore gill nets and long lines between April and October. Seventy-nine captured turtles were released, 73 of them with inconel flipper tags. Several turtles died from entanglement, serious injuries, slaughter for market, or diseases. An Olive Ridley Turtle and three Green Turtles were seen nesting at three beaches in southern and western Panay. Nesting of Hawksbill Turtles has been recorded at secluded beaches in Lawi, Guimaras about every three years; several batches of hatchlings have been raised by local residents before being released. Size-specific growth rates of Green Turtles and Hawksbill Turtles were highest among post-hatchlings and decreased sharply with size among juveniles and adults.

Juveniles of the giant tiger prawn, Penaeus monodon, were exposed for 10 days to 1 mg/l copper, lead, iron or calcium in order to investigate the formation and accumulation of metal granules in major soft tissues as well as their excretion from the body. Metal deposition was investigated by histochemistry and electron microscopy in the hepatopancreas and surrounding organs and tissues like the stomach, midgut, anterior midgut caecum, thoracal antennal gland extensions, haematopoietic tissue, and interspersed musculature, connective tissue and pigment tissue. The abundance of metal granules varied greatly between the metals and the tissues. Iron and calcium deposits were found in none of the tissues investigated. Copper granules were accumulated in high quantity in the hepatopancreas tubules, were scarce in the antechamber of the hepatopancreas, the anterior midgut and the anterior midgut caecum, and were lacking in the other tissues. The amount and size of copper granules increased along the hepatopancreas tubules in accordance with the cells' age. The granules were released by discharge of senescent hepatopancreas cells in the antechamber region and were added to the faeces. Lead granules were primarily found in the thoracal extensions of the antennal gland. In the hepatopancreas they occurred only in very small quantities, and in the other organs and tissues they were absent. In the antennal gland, the lead granules were individually discharged into the gland lumen by apocrine secretion and excreted with the urine. The observed ability of Penaeus monodon to detoxify and remove metals like copper and lead by granule formation and excretion and to prevent other metals like iron from entrance into major soft tissues corroborate that decapods are no suitable organisms for a long-term biomonitoring of heavy metal pollution.

Nifurpirinol (trade name Furanace and originally known as P-7138), is a nitrofuran derivative synthesized by the Dainippon Pharmaceutical Co. Ltd., Japan, and was developed exclusively as a broad-spectrum antibiotic for fish and other aquatic organisms (Shimizu and Takase 1967). It has been shown to have bactericidal and fungicidal action in vitro and in vivo (Shimizu and Takase 1967; Amend and Ross 1970; Pearse et al. 1974; Mitchell and Plumb 1980), and was used because of its excellent potential in controlling prawn diseases (Delves-Broughton 1974; Gacutan and Llobrera 1977). Milkfish (Chanos chanos Forsskal) is a widely-reared species and a very important aquaculture food crop in most parts of Southeast Asia. Thus, it was the logical choice as test animal for investigating the LC50 toxicity levels of nifurpirinol (6-hydroxymethyl-2-[2-(5-nitro-2-furyl) vinyl] pyridine) after 96 hr exposure. Changes in the normal gill architecture of milkfish after exposure to the drug were also studied (Tamse et al., in preparation).