Ionic composition of the seminal plasma and factors that initiate sperm motility in the freshwater Asian catfish Clarias macrocephalus, were examined to develop an artificial seminal plasma (ASP) that can be used to dilute milt. The optimum ratio of milt:ASP that can reversibly activate the sperm and milt–ASP:ovulated eggs that will result in high fertilization rates were further determined to minimize the number of males to be sacrificed during artificial insemination. Seminal plasma of C. macrocephalus contained 17.8±0.1 mM/l potassium, 164.4±0.6 mM/l sodium, 8.4±0.0 mM/l calcium and 1.6±0.0 mM/l magnesium, and had an osmolality of 269.0±6.4 mOsm/kg, and pH of 7.8±0.2. Sperm motility was highest and longest in all electrolyte (NaCl, CaCl₂, KCl) and non-electrolyte (mannitol) solutions of 200 mOsm/kg. Catfish sperm were motile in all isotonic NaCl–KCl solutions, and were reversibly activated in the ASP (143 mM NaCl, 30 mM KCl, 8 mM CaCl₂, 2 mM MgCl₂, 10 mM HEPES) solutions of pH 6.4–9.4. Altogether, these results suggest that sperm motility in C. macrocephalus was mainly initiated by a decrease in osmotic pressure, rather than ions and pH. High fertilization rates (89–94%) were observed when 10 μl milt, diluted with 1000 μl ASP, was activated with 5 ml of 0.6% NaCl (198.24 mOsm/kg) to fertilize 5 or 10 g of ovulated eggs. Results obtained from the present study provide information on sperm physiology that will lead to more efficient gamete management, and hopefully, an increase in the yield of catfish fry in the hatchery.

One generation of mass selection based on the collimation procedure (early culling of large fry) was applied on Nile tilapia, Oreochromis niloticus L., in net cages set in Laguna de Bay, Philippines. The objective was to test the effectiveness of a low-cost, small-scale broodstock improvement procedure in this culture environment. Directional selection was performed in two steps after initial removal of large fry at 21 days. Selection of parents and testing of the offspring were also conducted in hapa net cages set up in Laguna de Bay. The selection resulted in a significant positive response of 3% relative to the control, which represents a projected 34% gain over 5 years in Laguna cage culture. The realized heritability is approximately 16%.

We report the isolation and cDNA cloning of somatolactin (SL) from rabbitfish, Siganus guttatus. Rabbitfish SL was isolated from an alkaline extract of the pituitary glands by gel filtration chromatography on Sephadex G-100 and reversed-phase high-performance liquid chromatography. SL was monitored by immunoblotting with flounder SL antiserum. The preparation (yield: 0.86 mg/g wet tissues) contained two immunoreactive bands of 24 and 28 kDa on SDS-PAGE. Overlapping partial cDNA clones corresponding to teleost SLs were amplified by PCR from single-strand cDNA from pituitary glands. Excluding the poly(A) tail, rabbitfish SL cDNA is 1605 bp long. It contains a 693-bp open reading frame encoding a signal peptide of 24 amino acids (aa) and a mature protein of 207 aa. Rabbitfish SL has two possible N-glycosylation sites at positions 11 and 121 and seven half Cys residues. The deduced amino acid sequence shows over 80% identity with those of advanced teleosts like sea bream, red drum, and flounder, 76% with the salmonids, 57% with the eel, and 46% with the goldfish SL.

Aquaculture, the farming of shrimp and other useful aquatic and marine plants and animals in artificially confined and tended ponds, pens, and cages, ranks as a phenomenal success story in global food production. In 1975, aquaculture contributed 8% to the overall yield of the world's fish harvest; now it provides more than one-third of the yield. Total aquaculture production in 2003 was 54.8 million metric tons valued at $67.3 billion in U.S. dollars. More than 90% of this output comes from Asia, where aquaculture has its origins and where this month's essay author has lived and worked all of her life. In her essay, Jurgenne H. Primavera, senior scientist of the Aquaculture Department of the Southeast Asian Fisheries Development Center based in Iloilo, Central Philippines, traces the recent history of aquaculture and the socioeconomic and environmental challenges that its rapid growth has wrought, especially for the mangrove ecosystems in which much of brackishwater pond aquaculture occurs. With an eye on all stakeholders, Primavera lays out how aquaculture is now falling short of the goal of sustainability and what steps might be taken to move the industry in that direction.

Netcage culture of Nile tilapia, Oreochromis niloticus L., was conducted in a freshwater reservoir in Dingle, Iloilo, Philippines from February to October 2009 using Test diet (SEAFDEC/AQD) vs. Commercial feed A (Tateh) in the dry season and Test diet vs. Commercial feed B (Hoc Po) in the wet season. Percent crude protein for Test diet, Commercial feed A and Commercial feed B were 34–35%, 27–33% and 25–32%, respectively. Values for crude fat, crude fiber, crude ash and moisture were 6.0–6.5%, 3.5–5.0%, 10–12% and 4–12% for Test diet; 5–7%, 4.0–8.0%, 12% and 12% for Commercial feed A; and 7%, 4%, 12% and 12% for Commercial feed B, respectively. All netcages were stocked with tilapia fingerlings at 15 m^-3 with mean initial weight of 1.2 g and 1.3 g during the dry and wet seasons, respectively. The fish were fed with floating feeds for 87–89 d of culture. For the dry season, tilapia fed with Test diet had significantly higher (P<0.05) average body weight (ABW, 173.0 ± 1.3 g) and % survival (95.3 ± 2.2%) than Commercial feed A (158.0 ± 0.5 g, 92.0 ± 0.6%). Also, the absolute growth rate (AGR) of 1.97 ± 0.02 g d^-1, feed conversion rate (FCR) of 1.29 ± 0.01, final biomass of 154.60 ± 2.4 kg per cage and gross income of PhP 13,914 ± 18 for Test diet-fed tilapia were significantly higher (P<0.05) than those given Commercial feed A. For the wet season, tilapia fed with Test diet were not significantly different (P>0.05) in terms of ABW, survival, AGR, FCR, final biomass and gross income from those fed with Commercial feed B. During the dry season, tilapia fed with Test diet had significantly higher net income compared with those fed with Commercial feed A. There was no significant difference in terms of net income obtained for fish fed with Commercial feed B during the wet season compared with those fed with Test diet. The favorable return on investment (ROI), payback period and production cost per kilogram at 67.83%, 0.62 yr and PhP 46.72, respectively, were also shown by Test diet with a break-even price of PhP 67.55 and a break-even volume of 116 kg per crop. The overall production performance indicated that using cost-effective Test diet with high protein level would be a profitable and sustainable aquaculture venture during the dry season in the Philippines. In the wet season, however, the productive performance of tilapia and the efficiency of artificial feeds tested were relatively the same.

There is growing research interest in the ethnobiology, socio-economics and management of mangrove forests. Coastal residents who use mangroves and their resources may have considerable botanical and ecological knowledgeable about these forests. A wide variety of forest products are harvested in mangroves, especially wood for fuel and construction, tannins and medicines. Although there are exceptions, mangrove forest products are typically harvested in a small-scale and selective manner, with harvesting efforts and impacts concentrated in stands that are closer to settlements and easiest to access (by land or by sea). Mangroves support diverse, local fisheries, and also provide critical nursery habitat and marine productivity which support wider commercial fisheries. These forests also provide valuable ecosystem services that benefit coastal communities, including coastal land stabilization and storm protection. The overlapping of marine and terrestrial resources in mangroves creates tenure ambiguities that complicate management and may induce conflict between competing interests. Mangroves have been cut and cleared extensively to make way for brackish water aquaculture and infrastructure development. More attention is now given to managing remaining forests sustainably and to restoring those degraded from past use. Recent advances in remotely sensed, geo-spatial monitoring provide opportunities for researchers and planners to better understand and improve the management of these unique forested wetlands.

Partial sequence of the dnaJ gene of Vibrio harveyi, which was isolated from diseased juvenile Asian seabass, Lates calcarifer was identified. The partial sequence of dnaJ gene of V. harveyi was 447 bp and shared at least 77% identity at the nucleotide level with the dnaJ gene of other Vibrios. It was distinct from the dnaJ gene of other Vibrios but was closely related with the dnaJ gene of V. rotiferianus and V. campbellii having at least 90% nucleotide identity. PCR primers targeting this gene were designed to detect the pathogen in Asian seabass. The assay was specific to V. harveyi and the limit of detection was 100 pg of genomic DNA ml-1 or 100 fg of bacterial genomic DNA in a PCR reaction. This corresponded to a sensitivity of approximately 20 genome equivalents (GE) of V. harveyi. These results indicate that the dnaJ gene is a good candidate to develop primers for the PCR assay in detecting V.harveyi in fish.

Live transport of hatchery-produced juvenile donkey's ear abalone Haliotis asinina Linne was examined to evaluate the effect of transportation on the survival of juvenile abalone. Simulated transport experiments were conducted to determine the appropriate temperature using 5, 10 and 20 g L−1 of ice to air volume for 8 h and the appropriate size using two size groups (Size A, 15–20 mm, 0.5–1.3 g, and Size B, 30–35 mm, 5.3–8.5 g) up to 24-h out-of-water live transport. Survival was significantly higher (P<0.001) when 10 g L−1 of ice was used to decrease the temperature to the range of 17–23 °C. At this temperature, both size groups subjected to simulated transport for 8 and 10 h had 100% survival after 48 h, while mortality occurred in abalones subjected to 16 and 24 h of simulated transport. The Size B abalone subjected to 24 h of transport had significantly higher survival (64.4 ± 2.9%) (P<0.001) than the Size A abalone (5.5 ± 1.6%) after 48 h. Live juvenile abalone were successfully transported to the field applying the protocols developed in the lab experiment. This study serves as a guide for handling and shipping live juvenile abalone.

A series of verification runs on the farming of shrimp [Penaeus monodon (Fabricius)] using environment-friendly techniques was conducted in different pilot demonstration sites including privately owned farms in the Philippines from 2001 to 2005. Encouraging results were achieved using the low or partial discharge and closed-recirculating systems following the advanced environment-friendly protocols. In the low or partial discharge system, 11 grow-out ponds were stocked with P. monodon post larvae (PL) at densities between 15 and 25 m^-2 while in the closedrecirculating system, eight grow-out ponds were stocked with PLs at densities between 30 and 60 m^-2. Both systems incorporated the use of head and tail reservoirs, crop rotation, filter box, salinity reduction, long-arm paddlewheel aerators, biomanipulators, biofilters, sludge collectors and quality feeds. In the low or partial discharge system, an average total yield of 5.3 ± 0.8 tons ha^-1, a feed conversion ratio (FCR) of 1.4 ± 0.3 and a survival rate of 86 ± 12 % were achieved after 109–159 d of culture (DOC). In a closed recirculating system, however, an average total yield of 8.3 ± 4.0 tons ha^-1, FCR of 1.9 ± 0.2 and survival rate of 76 ± 15 % were achieved after 126–150 DOC. Analyses of effluents from grow-out ponds revealed that treatment using the tail reservoir with installed baffles and oysters (Crossostrea sp.) and seaweed (Gracilaria sp.) used as biofilters effectively reduced the dissolved organic nutrient concentration to optimum levels before the water was recycled or released to the surrounding body of water. Shrimps were observed to be growing and feeding normally, with no signs of bioluminescence at night, and no sluggish swimming behavior.

Two varieties of the carrageenophyte Kappaphycus alvarezii (Tungawan, TUNG; and Giant tambalang, GTAM) from Zamboanga Sibugay, Philippines were used to test the efficacy of Acadian Marine Plant Extract Powder (AMPEP) as source of nutrients for growth, and to determine if applications had any effect on the percent occurrence of an epiphytic infestation of the red alga Neosiphonia sp. at four different depths in the sea. Results showed that the use of AMPEP significantly (P < 0.05) increased the growth rate of both Kappaphycus varieties tested but decreased the percent occurrence of Neosiphonia sp. The percent occurrence of Neosiphonia sp. infection (6–50% at all depths) of both Kappaphycus varieties with AMPEP treatment was significantly lower than the controls (i.e., 10–75% at all depths). Both the growth rate of the cultivated seaweed and the percent occurrence of the epiphytes decreased as the cultivation depth increased. Plants dipped in AMPEP and suspended at the surface had the highest growth rates (i.e., 4.1%, TUNG; 3.1%, GTAM) after 45 days; those without AMPEP dipping had the highest percent occurrence of Neosiphonia infection (viz. 70–75%). The occurrence of Neosiphonia infestation was found to be correlated with changes in irradiance and salinity at the depths observed. The results suggested that both varieties of K. alvarezii used in this study have the fastest growth rate when grown immediately at the water surface. However, in order to minimize damage caused by the occurrence of epiphytic Neosiphonia, K. alvarezii should be grown within a depth range of 50–100 cm. These observations are important for the improved management of Kappaphycus for commercial farming. Furthermore, the use of AMPEP treatments for enhancement of growth and reduction deleterious Neosiphonia sp. infections is encouraging.