Subsistence-level and small-scale aquaculture systems dominate the aquaculture industry of most developing countires. Characterized by low material and management inputs, low level of technology, and low output, subsistence-level aquaculture is a system of farming that gives an inadequate economic return to the operator. It is argued that subsistence-level and small-scale aquaculturists must be given adequate government attention and institutional support: first, because these farming systems can be greatly improved; second, because they provide employment opportunities for the rural poor; and third, because aquaculture is a potential significant source of protein food for the poorer majority. The status of aquaculture in several developing countries is reviewed. Small-scale fishfarming characterized by traditional practices predominates in India, Bangladesh, Indonesia, Nepal, Thailand, Malaysia, and the Philippines. The pattern is similar in some African countries like Nigeria, Kenya, and the Sudan. A socioeconomic profile of the small fishfarmer is drawn. Aside from his low level of application of production and management inputs and his low output, he is highly susceptible to the vagaries of the market. His capacity to acquire improved technology on his own is low. To augment his earnings, he works in non-aquaculture occupations. The paper calls for a policy as well as a research and development bias for the subsistence fishfarmer. An aquaculture industry development support model is presented and a pilot-scale implementation scheme of this model is described. Finally, a mechanism is described for the transfer of local and borrowed aquaculture technology within a given country and among countries.

The susceptibility of different weight ranges of orange-spotted grouper (Epinephelus coioides) to piscine nodavirus was studied by experimental infection. Size ranges of 1-2 g, 6-8 g, 10-13 g, 30-60 g, and 90-120 g were intramuscularly injected with 50 µL 10⁶ TCID₅₀/mL of the cell culture supernatant. Clinical signs were observed and mortality occurred from 4 days post infection (dpi) for weight range 1-2 g to 7 dpi for weight range 30-60 g. Fish with weight ranges 1-2 g and 6-8 g showed highest susceptibility with mortality rate of 80% while fish with weight range 90-120 g were no longer susceptible. Mortality rates for weight ranges 10-13 g and 30-60 g were 50% and 20%, respectively. No mortality was observed in the 90-120 g weight range and the control group. These data show that the susceptibility of orange-spotted grouper to VNN is weight-dependent.

The nutritive value of four leguminous plant seeds: pigeonpea (Cajanus cajan), mungo (Phaseolus radiatus), kidneybean (Phaseolus vulgaris) and soybean (Glycine max), were evaluated as protein sources for milkfish (Chanos chanos) juveniles in isonitrogenous and isocaloric diets containing 40% protein. The legumes were heat-treated and added at different levels so that their protein contributed 25% of total dietary protein; peruvian fishmeal supplied the remaining portion. A diet with all protein contributed by fishmeal was used as a control. Substitution of 25% of the total 40% animal protein in the control diet by mungo and soybean meal did not adversely affect (P > 0.05) fish growth and the efficiency of feed conversion. Diets with 25% of protein contributed by pigeonpea and kidneybean meal resulted in significantly depressed (P ≤ 0.05) growth and efficiency of feed conversion. Milkfish survival rate was more than 97% throughout the six-week experimental period. We conclude that mungo and soybean meal, contributing at least 25% of dietary protein, can be used to replace fishmeal to reduce the cost of feed without adverse effect on the growth, survival and efficiency of feed conversion of juvenile milkfish.

The COVID-19 global pandemic has had severe, unpredictable and synchronous impacts on all levels of perishable food supply chains (PFSC), across multiple sectors and spatial scales. Aquaculture plays a vital and rapidly expanding role in food security, in some cases overtaking wild caught fisheries in the production of high-quality animal protein in this PFSC. We performed a rapid global assessment to evaluate the effects of the COVID-19 pandemic and related emerging control measures on the aquaculture supply chain. Socio-economic effects of the pandemic were analysed by surveying the perceptions of stakeholders, who were asked to describe potential supply-side disruption, vulnerabilities and resilience patterns along the production pipeline with four main supply chain components: a) hatchery, b) production/processing, c) distribution/logistics and d) market. We also assessed different farming strategies, comparing land- vs. sea-based systems; extensive vs. intensive methods; and with and without integrated multi-trophic aquaculture, IMTA. In addition to evaluating levels and sources of economic distress, interviewees were asked to identify mitigation solutions adopted at local / internal (i.e., farm-site) scales, and to express their preference on national / external scale mitigation measures among a set of a priori options. Survey responses identified the potential causes of disruption, ripple effects, sources of food insecurity, and socio-economic conflicts. They also pointed to various levels of mitigation strategies. The collated evidence represents a first baseline useful to address future disaster-driven responses, to reinforce the resilience of the sector and to facilitate the design reconstruction plans and mitigation measures, such as financial aid strategies.

A sampling of the protandric shrimp, Pandalus latirostris, was conducted at fixed sites from July 2015 to March 2020 in Akkeshi Bay and the connecting Lake Akkeshi on the Pacific coast of eastern Hokkaido. Based on the occurrence pattern of P. latirostris, most individuals begin mating as males at Age-1, followed by a sex change to females, spawn eggs as females at Age-2, and hatch their eggs in the spring of Age-3. Pre-hatching ovigerous females were mainly found in eelgrass beds near and in Lake Akkeshi, where the water temperature was relatively high. The females probably migrate there to hatch their eggs, making sure of the high survival and growth of the hatched larvae. Juveniles and small males were also abundant in near and in Lake Akkeshi, indicating that many larvae remained in the eelgrass beds where they hatched. These eelgrass beds play an important role in the maintenance of the shrimp population as a major egg-hatching site and nursery habitat in Akkeshi waters. With ontogenetic development, the occurrence rate of P. latirostris gradually increased on the offshore side of Akkeshi Bay, with its body size being larger. As P. latirostris grow, they will probably disperse to the offshore side of Akkeshi Bay. However, the density of P. latirostris in the eelgrass bed in the bay near the lake was extremely high, with its strong preference at all ontogenetic stages. This eelgrass bed would help maintain the shrimp population as a “key habitat” for the shrimp. The site-specific environmental characteristics of vegetation beds influence the distribution and abundance of individuals within a population of P. latirostris through their growth and the associated change in habitat preference. In this study, the importance of maintaining the diverse habitats of P. latirostris will be discussed as part of the shrimp stock management measures.

The tropical anguillid eel, Anguilla bicolor McClelland, experiences significant growth up to the adult size in both freshwater and estuarine ecosystems, encountering salinity gradients that may impact their reproduction. Therefore, this study aimed to investigate the reproductive aspects of A. bicolor collected from Serayu River (freshwater) and Segara Anakan (estuary), Cilacap, Central Java, during July 2020 field surveys. The examined parameters included eye index (EI), fin index (FI), gonadosomatic index (GSI), hepatosomatic index (HSI), and sex ratio of eel specimens in freshwater and estuary. Furthermore, the total length (TL) and body weight (BW) ranged from 260 - 630 mm and 18 - 419 g in freshwater, and 260 - 630 mm and 18 - 447 g in estuary. Significant differences (P<0.01) were observed in the reproductive characteristics between the two habitats (P<0.01), with higher eye index, fin index, gonadosomatic index, and hepatosomatic index in freshwater-caught eels than the values obtained in estuary inhabitants. The mean of these four parameters were 6.99 ± 2.98%, 4.08 ± 0.71%, 1.70 ± 1.13%, and 1.92% ± 1.07 in freshwater, while 3.48 ± 1.60%, 3.45 ± 0.479%, 1.12 ± 0.23%, and 0.28 ± 0.19% were found in estuary. The sex ratio was significantly affected by habitat, with female eels dominating in freshwater (62.5%) compared to estuary (32%). These results suggested that eels in freshwater habitats might exhibit early gonadal maturation compared to those in estuary.

There is a growing interest in the aquaculture of tropical anguillid eels as an export commodity. However, studies on feeding strategies, and the present demand to reduce feed costs need to be addressed to ensure the economic viability of eel farming. In this study, the effects of daily (DF) and alternate day (ADF) feeding on growth, feed utilization, body composition, blood chemistry, liver and intestinal morphology, and economic viability in the Pacific shortfin eel Anguilla bicolor pacifica were examined. Each feeding group of 30 elvers (166.25 ± 16.23 g mean initial wt) were randomly stocked in triplicate 4 m³ outdoor concrete tanks. These were fed for 155 d with formulated eel powder diet (49.77% crude protein; 10.21% crude lipid) made into a paste. Growth and survival were not significantly different between the two feeding groups. However, feed efficiency was improved in the ADF group, with significantly higher protein efficiency ratio (0.63) than in the DF group (0.39). Feed conversion ratio (FCR) was lower in ADF (3.85) than in the DF group (6.44), resulting in a 40% reduction in total feed consumption. Biometric indices, body proximate composition, and blood chemistry were not significantly affected. Likewise, liver and intestinal morphology showed no apparent alterations between groups. Partial costs-and-returns analysis showed that ADF yielded higher net profit and profit index. These results suggest that feeding on alternate days promote compensatory growth, better feed utilization, and normal physiological condition of A. bicolor pacifica, and reduce feed cost in the rearing process. Therefore, alternate day feeding should be promoted as a sound feed management strategy in the tank culture of tropical anguillid eels.

Scylla spp. are among the most economically important fisheries resources derived from the mangroves. However, the widespread mangrove destruction resulted in the loss of habitat, thus the dwindling capture production of many mangrove-associated faunas. Although studies have shown that Scylla populations have reestablished in mangrove-reforested areas, this study was the first in a mangrove-recolonized abandoned pond in the Philippines. Six fishers conducted standardized fishing every spring tide of the month using cylindrical bamboo traps. All crabs caught from July 2010 to December 2011 were recorded for species, sex, sexual maturation of females, carapace width (CW), and body weight (BW). Total landings comprised 14,262 crabs weighing 1,743 kg; 79.67% Scylla olivacea, 20.18% S. tranquebarica, and 0.15% S. serrata. CW ranged 3.1–17.1 cm and BW 10–1,250 g, with the male crabs comprising 39.23–64.65% of the monthly landings and the females distributed as 19.88–45.01% immature, 0.50–16.57% mature, 0.45–16.02% gravid, and less than 0.10% spent crabs. Monthly landings ranged 254–1,231 pcs of crabs or 32.38–160.59 kg. The monthly mean catch per unit effort (CPUE), in terms of number, was 0.101 ± 0.01–0.456 ± 0.02 crab gear⁻¹ day⁻¹ (max = 1.13), while in terms of biomass, 12.86 ± 0.84–54.36 ± 3.16 g gear⁻¹ day⁻¹ (max = 112.50). Length–weight relationships of S. olivacea and S. tranquebarica are expressed as W = 0.224967L^2.9864 (r² = 94.08%, p < 0.001; n = 11,363) and W = 0.173409L^3.1074 (r² = 92.71%, p < 0.001; n = 2,878), respectively. This study revealed that Scylla spp. could reestablish in mangrove-recolonized abandoned ponds.

Thraustochytrids have been targeted worldwide in search of highly oleaginous strains for industrial applications and newly collected holotypes are described based on life cycle developmental history and saccharide heterotrophy. Schizochytrium sp. OT01, a novel thraustochytrid protist from Panay, Philippines, distinguished from other reported strains by its asexual reproductive history - including the successive binary division of vegetative cells forming tetrads or octads, granular maturation of thalli into zoosporangia liberating heterokont motile zoospores and transformation of spheroidal thalli into amoeboid cells. Live-cell differential imaging and electron micrographs support its distinctive morphological features, such as hair-like pseudopodial astrals along hyaline margins of mature limaciform amoeboids and in motile zoospores prior to heterokont flagellum elongation. Moreover, its heterotrophic culture on certain saccharides (glucose, fructose, cellobiose, sucrose and starch) in continuously agitated fermentation condition was further investigated to determine hydrocarbon assimilative profiles as deduced from biomass yield and polyunsaturated fatty acid production. Increasing biomass yield was observed in increasing concentrations of saccharides; however, aside from glucose and fructose, a graphical drop of biomass was apparent beyond 15 gL, implying osmotic stress at these levels. Maximum biomass yield was observed at 30 gL- glucose and fructose concentration, reaching to about 6 g/l as expressed in freeze-dried weight of harvested cells, which indicates that OT01 could efficiently absorb and metabolize glucose and fructose compared to other hydrocarbons with relatively greater molecular weights. Even though biomass yield amounts were relatively low in cellobiose, sucrose and starch; however, docosahexaenoic acid (DHA) content in total fatty acids was relatively higher, amounting to 45.23, 46.25 and 48.86%, respectively. Moreover, oleagineity levels in glucose and fructose were highest, with lipid yield amounting to 655.55 and 609.38 mg, respectively, in every gram of freeze-dried weight cells. Consequently, DHA yield was significantly higher in both glucose and fructose, reaching respectively to 492.04 and 478.18 mg per liter of nutrient broth, which indicates higher absorption and metabolism efficiency of monosaccharides into fatty acids.

The Philippines is one of several countries in Southeast Asia that has, for several decades, made steady contributions to world aquaculture production both from inland and marine waters. In recent years, fish production has been on the decline mainly because of the lack of quality seedstock, limited stocks of captive breeders or spawners of major aquaculture commodities, adverse effects of climate change and other environmental factors on fish breeding and rearing, fish diseases caused by pathogenic organisms and prohibitive cost of aquaculture inputs such as feeds, etc. Genetic researches have been conducted mostly through local grants with the aim of addressing the aforementioned constraints. Such initiatives focused on developing and applying methods in (a) selective breeding; (b) marker-assisted genetic strain assessment for broodstock development and for monitoring inbreeding in farmed stocks and (c) genomics to understand and enhance on-farm stock performance through the identification of genes that are responsible for nutrition, stress and immune responses, among others. This paper highlights examples of local genetics applications in tilapia, mangrove crab, shrimp, milkfish and abalone aquaculture. The significance of implementing genetic interventions to boost and sustain aquaculture production in the Philippines is likewise discussed.