The availability of sexually mature fish often dictates the success of its captive breeding. In this study, we induced reproductive development in juvenile protogynous tiger grouper through oral administration of a plasmid (p) containing an engineered follicle-stimulating hormone (FSH). An expression construct (pcDNA3.1) was designed to express a single-chain FSH consisting of giant grouper FSH β-subunit and glycoprotein subunit-α (CGα), linked by the carboxy-terminal peptide (CTP) sequence from the human chorionic gonadotropin (hCG). Single oral delivery of pFSH encapsulated in liposome and chitosan to tiger grouper yielded a significant increase in plasma FSH protein level after 4 days. Weekly pFSH feeding of juvenile tiger groupers for 8 weeks stimulated ovarian development as indicated by a significant increase in oocyte diameter and progression of oocytes to cortical alveolar stage. As the pFSH treatment progressed from 20 to 38 weeks, female to male sex change was initiated, characterized by oocyte regression, proliferation of spermatogonial cells, and occurrence of spermatogenic cysts. It was also associated with significantly lower mRNA expression of steroidogenic genes (cyp11b, cyp19a1a, and foxl2) and basal plasma levels of sex steroid hormones 17β-estradiol (E₂), testosterone (T), and 11-ketotestosterone (11KT). Results suggest that pFSH stimulates ovarian development up to cortical alveolar stage and then initiates sex change in tiger grouper. These findings significantly contribute to our knowledge on the role of FSH in the development of protogynous hermaphroditic fish. This study is the first to demonstrate induction of reproductive development in fish through oral delivery of plasmid gonadotropin.

This manual addresses the lack of information materials on how to deal with marine turtle encounters in the Philippine seas to ensure that the proper treatment and intervention is provided. The manual also responds to the Comprehensive Action Plan for Threatened, Charismatic, and Migratory Species of the Sulu-Sulawesi Marine Ecoregion (SSME), which has been identified as the first priority seascape the Coral Triangle Initiative (CTI). The Tri-National Committee of the SSME developed the Comprehensive Action Plans (CAP) that identified seven Key Result Areas (KRAs) to improve the status of marine turtles in the SSME, as follows: (a) Identify best practices in minimizing threats to marine turtle populations and their habitats; (b) Develop and implement nesting habitats and management programs to maximize hatchling production and survival; (c) Provide recommendations on specific features or criteria in marine protected area (MPA) design and MPA network design in relation to the protection and management of marine turtles in SSME waters; (d) Undertake initiatives to promote reduction of incidental capture and mortality of marine turtles; (e) Conduct turtle population habitat research and monitoring protocols; (f) Develop guidelines for MPA network design for marine turtles; and (g) Publish information to promote best practices and successes for marine turtle conservation. This manual is an important step to address gaps and issues on threatened marine wildlife in the Philippines to better protect and conserve marine biodiversity in the Coral Triangle.

The giant grouper is presumed to follow the reproductive pattern of most Epinephelus species, characterized by protogynous hermaphroditism wherein male maturation is attained through sex reversal of a functional female. This hypothesis, however, has not been verified due to lack of biological data. The present study addresses this gap by investigating the reproductive development of giant groupers from juvenile stage through sexual maturity. Gonad histological analysis of hatchery-bred juvenile giant grouper from Queensland, Australia (0.8–5.2 kg, n = 43) have shown earliest occurrence of primary oocytes (i.e. ovarian differentiation) in 47.8 cm and 2.5 kg fish. Monitoring of sexual maturity by gonadal biopsy was performed in a stock of wild-caught giant groupers (2–52 kg) held in sea cages in the Philippines and Vietnam from 2015 to 2017. Onset of female sexual maturity was at 96.9 ± 1.6 cm and 23.5 ± 1.5 kg in the Philippines, and 103.0 ± 4.1 cm and 33.5 ± 2.5 kg in Vietnam. In both locations, development of primary males was observed wherein fish produced milt (or spermiated) without passing through a functional female phase. The ratio of primary males to females in both locations was about 1:2. Size at maturity of primary males is 86.5 ± 4.8 cm and 17.1 ± 2.1 kg in the Philippines, and 97.3 ± 1.3 cm and 34.3 ± 0.9 kg in Vietnam. To aid in the monitoring of female maturation, we developed a non-invasive method based on immunoassay of vitellogenin in skin mucus and this was shown to be effective in detecting female maturation 9 ± 2 months prior to first observation of oocytes through gonadal biopsy. Our findings suggest that giant grouper is a diandric protogynous hermaphrodite. This study provides novel information on the reproductive biology of giant grouper, an economically important and vulnerable species.

In Southeast Asian countries, aquaculture production continues to increase. Environmental deterioration associated with water and sediment eutrophication by aquaculture effluent has been problematic, sometimes resulting in disease outbreaks and fish kills due to hypoxia and hydrogen sulfide poisoning. Integrated multi-trophic aquaculture (IMTA) is one of the promising measures for sustainable aquaculture. In this study, a box model estimation of nitrogen (N) budget based on experimental data and values from literature was made for a system of sandfish (Holothuria scabra) in sea cage IMTA with milkfish (Chanos chanos) and Elkhorn sea moss (Kappaphycus alvarezii). Information on stocking density, stocking size, mortality, growth, feed ration, feed assimilation, NH4-N production and NH4-N absorption of these species was obtained from a series of experiments and existing literature. In the production system 26 g milkfish were cultured in a 5 x 5 x 4 m cage at the stocking density of 36.7 ind/m³ with the initial feeding ration of 10% of body weight which was gradually decreased to 4% over time; 10 g sandfish were cultured in a cage with the same bottom area as milkfish cage hanged under the milkfish cage to trap particulate N waste (i.e. feces and leftover feed) at the stocking density of 35 ind/m²; the stocking weight of Elkhorn sea moss line culture was 10 kg; culturing period was 200 days. It was estimated that milkfish culture cumulatively produced 145 kg of particulate N, and milkfish and sandfish together produced 60 kg of NH₄-N in 200 days of culture. Daily assimilation rate of the particulate N by sandfish ranged 3.4 - 12.4%, and 4.3% of the particulate N was estimated to be removed by sandfish in 200 days of culture. Daily absorption rate of NH₄-N by Elkhorn sea moss increased exponentially with time and reached 100% after 125 days of culture. Cumulative NH₄-N was estimated to be depleted after 162 days of culture. For complete utilization of particulate N by the end of culture, sandfish stocking density should be 805 ind/m², which is 200 times as high as that in existing sandfish aquaculture operations.

Survival and growth of mud crabs and any other crustaceans depend on molting. Molting is influenced by several hormones, two of which are Molt-Inhibiting Hormone {MIH} and a molt promoting hormone, the Extracellular Signal-regulated Kinase (ERK). Controlling and synchronizing the molting of the crabs would be a big boost to the mud crab industry, especially in the production of soft shell crabs. The best way to control molting would be to stock juvenile crabs of the same molting stage together. In this study, hormone expressions were analyzed using quantitative Real-Time Polymerase Chain Reaction (1RT-PCR). Molt stages of 36 juvenile S. serrata were established based on MIH and ERK expression levels that was analyzed using Principal Component Analysis (PCA). One group of six individuals had MIH value equal to zero and presumed to be in the PR stage. The rest of the crabs had values for MIH and were presumed to be in the PM-IM stage. The value of ERK for the PM-IM stage was higher at 24.79 than in the PR stage at 21.67. Based on the data gathered, morphological markers may now be identified to standardize hormone expression. This would be the first study concerning the comparison of hormones during molting.

Erythrocytic inclusion body syndrome (EIBS) causes mass mortality in farmed salmonid fish, including the coho salmon, Onchorhynchus kisutchi, and chinook salmon, O. tshawytscha. The causative agent of the disease is a virus with an icosahedral virion structure, but this virus has not been characterized at the molecular level. In this study, we sequenced the genome of a virus purified from EIBS-affected coho salmon. The virus has 10 dsRNA genomic segments (L1, L2, L3, M1, M2, M3, S1, S2, S3, and S4), which closely resembles the genomic organization of piscine orthoreovirus (PRV), the causative agent of heart and skeletal inflammation (HSMI) in Atlantic salmon and HSMI-like disease in coho salmon. The genomic segments of the novel virus contain at least 10 open reading frames (ORFs): lambda 1 (λ1), λ2, λ3, mu 1 (μ1), μ2, μNS, sigma 1 (σ1), σ2, σ3, and σNS. An additional ORF encoding a 12.6-kDa protein (homologue of PRV p13) occurs in the same genomic segment as σ3. Phylogenetic analyses based on S1 and λ3 suggest that this novel virus is closely related to PRV, but distinctly different. Therefore, we designated the new virus ‘piscine orthoreovirus 2’ (PRV-2). Reverse transcription–quantitative real-time PCR revealed a significant increase in PRV-2 RNA in fish blood after the artificial infection of EIBS-naïve fish but not in that of fish that had recovered from EIBS. The degree of anemia in each fish increased as the PRV-2 RNA increased during an epizootic season of EIBS on an inland coho salmon farm. These results indicate that PRV-2 is the probable causative agent of EIBS in coho salmon, and that the host acquires immunity to reinfection with this virus. Further research is required to determine the host range of PRV species and the relationship between EIBS and HSMI in salmonid fish.

Mud crabs, Scylla spp., are commercially important large-size marine crustaceans in the Indo-West Pacific region. As females have the higher growth rate and economic value, the production of all female stocks is extremely essential in aquaculture. However, the sex determination mechanism is still unclear. Development of sex-specific genetic markers based on next-generation sequencing proved to be an effective tool for discovering sex determination system in various animals.

The role of follicle stimulating hormone (FSH) in the gonadal development of protogynous hermaphroditic grouper (E. fuscoguttatus) was investigated. Recombinant giant grouper (E. lanceolatus) FSH (rggFSH) was produced in yeast. Its receptor binding capacity and steroidogenic potency were confirmed in vitro. Weekly injections of rggFSH to juvenile tiger grouper for 8 weeks (100 μg/kg body weight, BW) resulted in significantly larger and more advanced oocytes (cortical alveolar stage vs. primary growth stage in control). Sustained treatment with rggFSH (20 to 38 weeks at 200 μg/kg BW) resulted in significant reduction in gonad size, degeneration of oocytes and proliferation of spermatogonial cells, indicative of female to male sex change. Gene expression analysis showed that, while initiating female to male sex change, the rggFSH significantly suppressed the steroidogenic genes cyp11b, cyp19a1a and foxl2 which restrained the endogenous production of sex steroid hormones thus prevented the differentiation of spermatogonial cells. Expression profile of sex markers dmrt1, amh, figla and bmp15 suggests that the observed sex change was restricted at the initiation stage. Based on these results, we propose that the process of female to male sex change in the protogynous grouper is initiated by FSH, rather than sex steroids and likely involves steroid-independent pathway. The cortical alveolar stage in oocyte development is the critical point after which FSH-induced sex change is possible in grouper.

Understanding the information-seeking behavior of library patrons is essential for the library to provide quality resources and services, and to satisfy its patrons’ information needs. A quantitative research was conducted to describe the information searching and using behaviors of the Filipino aquaculture scientists, researchers and research staff at the Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC/AQD). The study revealed that although the respondents find it useful to go to the library to get assistance from the librarian, and to browse and read current acquisitions related to their research, they visited the library infrequently. However, remote library services, especially email and phone services, were highly utilized. When searching for information, the Internet, mainly via search engines, was highly preferred rather than visiting the Library and using its online public access catalog (OPAC) or its databases. The combination of print and electronic formats was highly preferred when reading, rather than print only or electronic-only. The majority would print and save the retrieved electronic copy.

This report is part of a national overview of agricultural pollution in the Philippines, commissioned by the World Bank. The overview consists of three ‘chapters’ on the crops, livestock, and fisheries sub-sectors, and a summary report. This ‘chapter’ provides a broad national overview of: (a) the magnitude, impacts, and drivers of pollution related to the fisheries sector’s development with a focus on aquaculture; (b) measures that have been taken by the public sector to manage or mitigate this pollution; and (c) existing knowledge gaps and directions for future research. This report was prepared on the basis of existing literature, recent analyses, and national and international statistics, as well as extensive interviews. It did not involve new primary research and did not attempt to cover pollution issues that arise in the broader aquaculture value chain, relating for instance to processing, packaging and transportation, feed processing, or veterinary drug factories.