Luminous bacterial disease caused by Vibrio harveyi has devasted the shrimp industry. The use of different strains of tilapia and other fish species polycultured with shrimp cultured at a salinity of 24 ppt to control luminous bacteria has been reported. These species, however, could not tolerate salinities higher than 24 ppt. Alternative species/strains that could be used to control luminous bacteria at high salinities need to be investigated. Likewise, the effect of fish size on the growth of luminous bacteria is worth studying. Shrimp (Penaeus monodon Fabricius) were stocked in concrete tanks filled with 34 ppt cartridge filtered seawater. Tanks were stocked with two sizes (16 pcs, average body weight (ABW) = 55 g and 6 pcs ABW=250 g) of the red tilapia hybrid Oreochromis mossambicus Peters x O. niloticus Linnaeus, except for the tanks that served as the control. Luminous bacteria (V. harveyi) were inoculated into the tank water to a density of 10⁴ Cfu mL^-1. Significantly lower luminous bacterial count was observed in tanks with either of the two sizes of red tilapia hybrid compared with the control, after 5-7 d. Bacteria isolated from the fish feces, mucus and rearing water; and the fish feces and mucus themselves demonstrated anti-V. harveyi activity. Results showed that the red tilapia hybrid could be used to control luminous bacteria at salinities as high as 34 ppt and that the size of the fish did not affect its efficiency. The ability of the red tilapia hybrid to control the growth of the luminous bacteria V. harveyi is attributed to different factors such as the mucus, the feces and the bacteria associated with tilapia culture. Bacteria associated with the fish mucus and feces also contributed to the anti-V. harveyi activity of these biological substances.

Growth of several genetically improved Nile tilapia (GIFT or Genetically Improved Farmed Tilapia, FaST or Freshwater Aquaculture Center Selected Tilapia, SEAFDEC-selected) and domesticated red tilapia (BFS or Binangonan Freshwater Station, NIFI-red or National Inland Fisheries Institute red, HL or Hacienda Luisita) stocks were compared in controlled (tank) and uncontrolled farm conditions (lake-based cages) with unselected NIFI or Chitralada Nile tilapia as control. Specific growth rate differed significantly (P = 0.009) in tank-reared Nile tilapia stocks where GIFT grew best at 1.358%/day followed by FaST (1.307%/day), control stock NIFI (1.257%/day) and SEAFDEC-selected (1.202%/day). Genetic effect explained 84.4% of the variance in growth of Nile tilapia in tanks. Although Nile tilapia growth in cages followed the same trend where GIFT grew best at 1.570%/day, no significant stock differences (P = 0.479) were noted. Meanwhile, red tilapia reared in either tanks or cages showed no significant stock differences in terms of growth. However, survival of the red tilapia stocks in cages differed significantly with HL having the highest percentage survival at 93.3%. The different growth responses of the Nile tilapia stocks especially under controlled (tank) farm conditions were largely due to genetic factors (stock differences).Under uncontrolled farm conditions, environmental factors were generally observed to have also affected the survival and to some extent, the growth of Asian Nile and red tilapia stocks.

Carposporophytes of the seaweed, Kappaphycus striatum, from the wild were made to shed spores in the laboratory and grown in multi-step culture method until they reached maturity. For each succeeding transfer onto increasingly bigger culture vessels, there was a marked increase in the growth of carposporelings. When plantlets were ready for outdoor culture, they were placed in aquaria and concrete tanks and later moved to the sea in net cage and long-line for grow-out culture. Successfully growing sporelings from carposporophytes in the laboratory until they reach market size seems to depend on the stage of sporelings and environmental factors such as photoperiod and temperature. In this study, carpospore progenies (diploids) also matured into tetrasporophytes and haploid progenies showed resistance to higher temperature.

The reduction of the survival of mud crab during culture has been largely attributed to aggressive encounters and cannibalism. In some crustaceans, suppressed aggression is linked to increased concentration of circulating and brain serotonin (5-hydroxytryptamine, 5-HT). Likewise, tryptophan (TRP), a precursor of 5-HT is reported to suppress the aggression and improve the survival of some cultured fish through dietary supplementation. We investigated the effects of feeding formulated diet with different TRP levels (0.32% as control, 0.5%, 0.75% and 1% of dry diet) on the agonistic behavior, growth and survival of juvenile mud crab Scylla serrata. Mud crabs were individually stocked and fed the experimental diets for 4 weeks before they were set to a one hour fight experiment. The fights were recorded using a video camera and the aggressiveness of the crabs was quantified. Hemolymph was sampled after 15 and 30 days of feeding (resting) and right after the fight to measure circulating 5-HT concentration. Higher TRP levels suppressed the aggressiveness of mud crab in a dose dependent manner. The intensity and frequency of attacks were both significantly lower (P < 0.05) in those given diets containing 0.75% and 1% TRP as compared with the control. Serotonin-ELISA assay revealed that 5-HT levels in the hemolymph before the fight (after 15 and 30 days; resting) were not significantly different between treatments. However after the fight, 5-HT concentration was significantly higher in TRP-supplemented mud crabs as compared with the control (0.5% = P < 0.05; 0.75% and 1% = P < 0.01). Furthermore, mud crabs (0.16 g BW) were reared in 0.40 m² circular tanks at 20 crabs/tank and fed the experimental diets for 30 days to determine growth and survival. Survival was higher in TRP-supplemented mud crabs (0.5% = 35%, 0.75% = 33.33%, 1% = 35%) as compared with the control (18.33%). However, daily growth gain (DRG), relative growth rate (RGR) and specific growth rate (SGR) were reduced in TRP-supplemented groups than with the control group. In conclusion, the data shows that the aggressive behavior of juvenile mud crab can be suppressed by supplementation of L-TRP. The survival of juvenile mud crab can be improved by increasing the level of TRP to 0.5%–1%. However, higher TRP levels may affect growth of mud crab. TRP supplementation resulted to a significant increase of 5-HT concentration in the hemolymph which was clearly observed after the fight suggesting that 5-HT plays an important role in suppressing the agonistic behavior of mud crab during aggressive encounters.

The effect of feeding four diatom diets (Amphora sp., Navicula ramosissima, Amphora sp. + N. ramosissima, and mixed diatoms) and two attachment substrates (PP+CCA: polyvinyl plates with crustose coralline algae; PP-CCA: polyvinyl plates without crustose coralline algae) were determined for seed production of abalone, Haliois asinina. On day 5, significantly higher number of larvae settled on PP+CCA fed with mixed diatoms followed by Amphora sp., N. ramosissima, Amphora sp. + N. ramosissima, and abalone larvae reared on PP-CCA fied with N. ramosissima only. Fewer larvae settled on PP-CCA fed with Amphora + N. ramosissima, Amphora sp. and mixed diatoms. The size of abalone juveniles from PP-CCA was significantly bigger compared with juveniles measured from PP+CCA. However, the number of juveniles harvested from tanks provided with PP+CCA was higher compared with tanks with PP-CCA. This study has shown that crustose coralline algae favored the settlement of H. asinina larvae and inoculation of diatom slurry is necessary to provide sufficient food for the growing larvae.

To evaluate the impact on biota of the release of arrow up million liters of bunker oil off Guimaras Island, Central Philippines, the penaeid shrimp populations in a protected island mangrove (Tandog) and a riverine mangrove (Sibunag) were surveyed by pocket seine 2-3 months after the August 2006 spill; results are compared to 1993 baseline data. A total of 529 individuals belonging to three penaeid species were collected - Metapenaeus anchistus in Tandog, and Metapenaeus ensis and Penaeus merguiensis in Sibunag. Shrimp densities were significantly higher in Tandog Island in 2006 compared to 1993 but remained similar in the riverine mangrove. This suggests that protection may have a greater impact than the Oil Spill per se because Tandog is part of the protected Taklong National Marine Reserve. In contrast to abundance, shrimp sizes (carapace length) were significantly smaller in 2006 compared to 1993 for both sites.

Increasing population, ineffective management, competition among fishing gears over access to resources and proliferation of destructive practices are imposing severe stress on the inland water bodies of Bangladesh. These factors also contribute to the increasing incidence of conflicts among fishery stakeholders. When unabated, these conflicts are potential threats to the livelihoods of millions of the poorest fishing communities that depend on these resources. Effective communication between conflicting parties is perceived as a key for establishing successful negotiations for managing conflicts. On this premise, this paper presents and assesses a Fisheries Conflicts Communication Framework, henceforth called FishCom, a tool for developing plans and strategies for managing fisheries conflicts in the inland fisheries of Bangladesh. This tool embodies a structured participatory process intended for use by policy-makers and conflict management practitioners. They have important roles in catalyzing and effecting changes that are instrumental in minimizing, if not totally eliminating conflicts. Experiences from applying FishCom in the inland fisheries study sites in Bangladesh show that it has enabled a systematic stakeholder-inclusive identification and evaluation of fisheries conflicts and planning of communication interventions to manage them.

Ranching, stock enhancement and restocking are management approaches involving the release of wild or hatchery-bred organisms to enhance, conserve or restore fisheries. The present study, conducted from April 2002 to November 2005, evaluated the effectiveness of releasing wild and hatchery-reared (HR) mud crabs in the mangroves of Ibajay, Aklan, Philippines where preliminary studies demonstrated declining fishery yields, abundance and size of crabs. Comparison of survival and growth of wild-released and HR Scylla olivacea and HR Scylla serrata demonstrated the effect of nursery conditioning, size-at-release and species differences. Overall yield and catch per unit effort (CPUE) increased by 46% after stock enhancement trials. Recapture rates of released crabs were highest in wild-released S. olivacea and in crabs measuring 65.0–69.9 mm carapace width (CW) and lowest in non-conditioned HR S. serrata. Growth rates were highest for conditioned HR S. olivacea and lowest for conditioned HR S. serrata (11.7 and 3.7 mm month^-1 respectively). Fishing mortality was highest for S. olivacea, whereas natural mortality was greater for S. serrata. Conditioning hatchery-bred animals before release is also important in obtaining higher survival. S. olivacea was the more appropriate of the two species for release in mangrove habitats inundated with low-salinity water. However, there is a need for site-specific studies to evaluate the effectiveness of releases.

Natural processes tend to vary over time and space, as well as between species. The ecosystem services these natural processes provide are therefore also highly variable. It is often assumed that ecosystem services are provided linearly (unvaryingly, at a steady rate), but natural processes are characterized by thresholds and limiting functions. In this paper, we describe the variability observed in wave attenuation provided by marshes, mangroves, seagrasses, and coral reefs and therefore also in coastal protection. We calculate the economic consequences of assuming coastal protection to be linear. We suggest that, in order to refine ecosystem-based management practices, it is essential that natural variability and cumulative effects be considered in the valuation of ecosystem services.

This study explored the interdependencies of aquaculture markets in the Philippines by establishing price cointegration between wholesale and retail prices of three major species commonly farmed in the country, i.e., milkfish, tilapia and shrimp. The co-movements of wholesale prices between and among key markets for each species were also investigated. Moreover, exogeneity in prices was established using Granger-causation model to determine the existence of price leaders among these markets. Such information are crucial in farm management decisions of producers and traders through better understanding of the efficiency in price formation across production and consumption centers which in turn defines the movements in prices and products among markets. Appropriate policies for the development of markets for the three aquaculture species were also identified. Such policies are expected to contribute towards the attainment of efficient pricing and distribution of benefits among market players and stakeholders. These benefits are expected to manifest through the system of grading standards for fish traded in local markets and in the choice of cost-effective technologies in grow-out and post-production practices.