Now showing items 1-20 of 26

    • Article

      Changes in mRNA expression of grouper (Epinephelus coioides) growth hormone and insulin-like growth factor I in response to nutritional status 

      FL Pedroso, EGT De Jesus-Ayson, HH Cortado, S Hyodo & FG Ayson - General and Comparative Endocrinology, 2006 - Elsevier
      Growth hormone (GH) and insulin-like growth factor-I (IGF-I) are key links to nutritional condition and growth regulation in teleost. To understand the endocrine mechanism of growth regulation in grouper, we cloned the cDNAs for grouper GH and IGF-I and examined their mRNA expression during different nutritional status. Grouper GH cDNA is 936 base pairs (bp) long excluding the poly-A tail. It contained untranslated regions of 85 and 231bp in the 5'- and 3'-ends, respectively. It has an open reading frame of 612bp coding for a signal peptide of 17 amino acids (aa) and a mature hormone of 187aa residues. Based on the aa sequence of the mature hormone, grouper GH shows higher sequence identity (>76%) to GHs of perciforms than to GHs of cyprinids and salmonids (53-69%). Grouper preproIGF-I cDNA consisted of 558bp, which codes for 186aa. This is composed of 44aa for the signal peptide, 68aa for the mature peptide comprising B, C, A, and D domains, and 74aa for the E domain. Mature grouper IGF-I shows very high sequence identity to IGF-I of teleost fishes (84-97%) compared to advanced groups of vertebrates such as chicken, pig, and human (=<80%). Using DNA primers specific for grouper GH and IGF-I, the changes in mRNA levels of pituitary GH and hepatic IGF-I in response to starvation and refeeding were examined by a semi-quantitative RT-PCR. Significant elevation of GH mRNA level was observed after 2 weeks of food deprivation, and increased further after 3 and 4 weeks of starvation. GH mRNA level in fed-controls did not change significantly during the same period. Hepatic IGF-I mRNA level decreased significantly starting after 1 week of starvation until the 4th week. There was no significant change in IGF-I mRNA levels in fed-controls. One week of refeeding can restore the GH and IGF-I mRNA back to its normal levels. Deprivation of food for 1-4 weeks also resulted in cessation of growth and decrease in condition factor.
    • Article

      Cloning of mangrove red snapper (Lutjanus argentimaculatus) growth hormone cDNA and mRNA expression during early development 

      LP Samentar, FG Ayson, EGT de Jesus-Ayson & MJ Formacion - Philippine Journal of Natural Sciences, 2013 - University of the Philippines Visayas
      Growth hormone regulates growth and development in vertebrates. As a first step to understand the role of growth hormone in the regulation of growth and development of the mangrove red snapper Lutjanus argentimaculatus, the red snapper growth hormone (sGH) cDNA was cloned using reverse transcription - polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends. The expression of sGH mRNA in embryos and larvae was examined also by RT-PCR. Excluding the poly-A tail, the full-length red snapper GH cDNA is 945 base pairs (bp) long. It contains untranslated regions of 99 bp and 234 bp in the 5’ and 3’ ends, respectively. It has an open reading frame of 612 bp coding for a signal peptide of 17 amino acids and a mature hormone of 187 amino acid residues. Red snapper GH contains 4 cysteine residues and the typical polyadenylation site 16 bp upstream of the poly-A tail. Based on the amino acid sequence of the mature hormone, sGH shows higher sequence identity (>75%) to GHs of perciforms like grouper, seabass, tilapia and rabbitfish than to GHs of salmonids and carps. Semi-quantitative RT-PCR showed that expression of sGH mRNA commenced two days after hatching.
    • Article

      Cortisol stimulates the size and number of mitochondrion-rich cells in the yolk-sac membrane of embryos and larvae of tilapia (Oreochromis mossambicus) in vitro and in vivo 

      FG Ayson, T Kaneko, S Hasegawa & T Hirano - Journal of Experimental Zoology, 1995 - John Wiley and Sons
      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.
    • Book

      Development and management of milkfish broodstock 

      OS Reyes, EGT de Jesus-Ayson, BE Eullaran, VL Corre Jr. & FG Ayson - 2015 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 62
      The manual provides developed and refined techniques for collection and transport of spawned eggs and larvae, as well as larval rearing. It also describes the necessary facilities for maintaining milkfish broodstock.

      Guidelines on transporting broodstock, performing biopsy to determine sex of spawners, collecting and cleaning eggs, packing and transporting eggs to hatchery, incubating and hatching eggs, and packing and transporting of larvae are also provided in the manual.

      The importance of nutritional quality of the diet in relation to the performance of the milkfish broodstock and quality of resulting eggs and larvae is also explained in the manual.

      Broodstock feeds are enriched with vitamin C, beta-carotene, and other nutrients for better reproductive performance of broodstock and better egg and larval quality. It also offers formula to initially estimate the number of spawned eggs and determine the hatching rate.

      The manual guides stakeholders and operators who are interested in setting up breeding facilities for milkfish.
    • Article

      Differential expression of insulin-like growth factor I and II mRNAs during embryogenesis and early larval development in rabbitfish, Siganus guttatus 

      FG Ayson, EGT de Jesus, S Moriyama, S Hyodo, B Funkenstein, A Gertler & H Kawauchi - General and Comparative Endocrinology, 2002 - Academic Press
      In rodents, the expression of insulin-like growth factor II (IGF-II) is higher than that of insulin-like growth factor I (IGF-I) during fetal life while the reverse is true after birth. We wanted to examine whether this is also true in fish and whether IGF-I and IGF-II are differentially regulated during different stages of embryogenesis and early larval development in rabbitfish. We first cloned the cDNAs of rabbitfish IGF-I and IGF-II from the liver. Rabbitfish IGF-I has an open reading frame of 558 bp that codes for a signal peptide of 44 amino acids (aa), a mature protein of 68 aa, and a single form of E domain of 74 aa. Rabbitfish IGF-II, on the other hand, has an open reading frame of 645 bp that codes for a signal peptide of 47 aa, a mature protein of 70 aa, and an E domain of 98 aa. On the amino acid level, rabbitfish IGF-I shares 68% similarity with IGF-II. We then examined the relative expression of the two IGFs in unfertilized eggs, during different stages of embryogenesis, and in early larval stages of rabbitfish by a semiquantitative reverse transcription-polymerase chain reaction. Primers that amplify the mature peptide region of both IGFs were used and PCR for both peptides was done simultaneously, with identical PCR conditions for both. The identity of the PCR products was confirmed by direct sequencing. Contrary to published reports for seabream and rainbow trout, IGF-I mRNA was not detected in rabbitfish unfertilized eggs; it was first expressed in larvae soon after hatching. IGF-II mRNA, however, was expressed in unfertilized eggs, albeit weakly, and was already strongly expressed during the cleavage stage. mRNAs for both peptides were strongly expressed in the larvae, although IGF-II mRNA expression was higher than IGF-I expression.
    • Book chapter

      Early development and seed production of Asian seabass, Lates calcarifer 

      EG de Jesus-Ayson, FG Ayson & V Thepot - In DR Jerry (Ed.), Biology and Culture of Asian Seabass Lates Calcarifer, 2014 - CRC Press
      This Chapter outlines the characteristics of L. calcarifer eggs and larvae, the changes during embryonic and larval development, advances in seed production and at the same time highlights the relative ease in its mass production.
    • Article

      The effect of stress on spawning of brood fish and survival of larvae of the rabbitfish, Siganus guttatus (Bloch) 

      FG Ayson - Aquaculture, 1989 - Elsevier
      The effects of stress due to handling, and repeated sham and human chorionic gonadotropin (HCG) injections on spawning and survival of the rabbitfish, Siganus guttatus were studied. Results showed that stress significantly enhanced spawning in captive females, but apparently has no significant effect on the survival of larvae. The results indicate that factors other than stress are responsible for the high variability in larval survival in the hatchery. In addition, the results clearly demonstrate the necessity of exogenous gonadotropin to ensure 100% monthly spawning of captive S. guttatus females.
    • Article

      Environmental control of annual reproductive cycle and spawning rhythmicity of spinefoots 

      A Takemura, Y Takeuchi, T Ikegami, SP Hur, V Soliman, F Ayson, E de Jesus-Ayson & ES Susilo - Kuroshio Science, 2015 - Graduate School of Kuroshio Science, Kochi University
      Many teleost fishes inhabiting shallow tropical waters exhibit synchronous spawning around species-selective lunar phases during their spawning season. For example, ovaries of the goldlined spinefoot (Siganus guttatus) develop during a single period each year from June to July in the Ryukyu Islands, Japan, while those of the goldlined spinefoot in the Karimunjawa Archipelago, Indonesia, develop twice a year from March to May, and then again from September to November. Increases in photoperiod and water temperature are possible cues for the initiation of reproductive activity in the populations around the Ryukyu Islands, while the transition between the rainy and dry season may trigger the initiation of reproductive activity in the Karimunjawa Archipelago populations. Moreover, the goldlined spinefoot releases its gametes around the first quarter moon period of the lunar phase, and since the lunar phase is consistent within the Indo-Pacific Ocean, this species can likely perceive cues from the moon and transcribe them as internal signals. In fact, periodical changes in moonlight intensity are expressed as changes in the plasma levels of melatonin, an endogenous transmitter of environmental light/dark cycles. In addition, the mRNA expression levels of clock genes of neural tissues [Cryptochrome (Cry3) and Period (Per2)] change according to changes in the lunar cycle. To date, how the lunar cycle may affect endogenous reproductive processes in fish is not fully understood. However, knowledge of lunar spawning periodicity in commercially important species may help in the management of fisheries resources, determining where and when to prohibit fishing (e.g., time and area closures), as well as promoting efficient aquaculture techniques for inducing synchronous spawning.
    • Article

      Expression and purification of a biologically active recombinant rabbitfish (Siganus guttatus) growth hormone 

      B Funkenstein, D Dyman, Z Lapidot, EG de Jesus-Ayson, A Gertler & FG Ayson - Aquaculture, 2005 - Elsevier
      Recombinant rabbitfish growth hormone (rfGH) protein was expressed in Escherichia coli, BL21(DE3) cells. The cDNA encoding the mature protein of rfGH was first cloned in pGEM-Teasy vector and then transferred to pET-3d expression vector. Expression in E. coli cells was then induced by IPTG (0.4 mM). Inclusion bodies (IB) containing the expressed protein were purified by treating bacterial cells pellet with lysozyme followed by repeated washings in cold water containing Triton X-100, sonication, and centrifugation. IB were then solubilized in 4.5 M urea, refolded at pH 11.3 in the presence of catalytic amounts of cysteine and purified by Q-Sepharose column. Gel filtration on Superdex column showed the purified protein to be a monomeric GH. Based on SDS–PAGE, the purity of the recombinant rfGH preparation is approximately 98%. The recombinant rfGH was tested for its biological activity both in vitro, by its ability to stimulate IGF-I mRNA expression in the liver, and in vivo, by its ability to accelerate growth in rabbitfish fry injected with the hormone. A significant increase in growth was observed in rabbitfish fry given the recombinant hormone. Polyclonal antibody raised against the native rfGH immunoreacted with the recombinant rfGH in Western blots and in ELISA, indicating the suitability of these reagents for future quantification of GH in rabbitfish plasma.
    • magazineArticle

      Facing the challenges in aquaculture through biotechnology 

      FG Ayson - SEAFDEC Asian Aquaculture, 2002 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Article

      Gonadal response of juvenile protogynous grouper (Epinephelus fuscoguttatus) to long term recombinant follicle-stimulating hormone administration 

      P Palma, J Nocillado, J Superio, EGdJ Ayson, F Ayson, I Bar & A Elizur - Biology of Reproduction, 2018 - Oxford University Press
      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.
    • Article | Review

      Growth regulation by insulin-like growth factor-I in fish 

      S Moriyama, FG Ayson & H Kawauchi - Bioscience, Biotechnology and Biochemistry, 2000 - Japan Society for Bioscience, Biotechnology, and Agrochemistry
      Insulin-like growth factor-I (IGF-I) is a mitogenic polypeptide that plays an essential role in the regulation of development and somatic growth of vertebrates, mainly by mediating growth hormone actions. It has clearly been established that the structure of IGF-I and its biological function has been highly conserved among vertebrates. In this paper, we review the recent developments in the molecular, biochemical, and physiological properties of IGF-I in fish.
    • Article

      Induced spawning of rabbitfish, Siganus guttatus (Bloch) using human chorionic gonadotropin (HCG) 

      FG Ayson - Aquaculture, 1991 - Elsevier
      A positive spawning response of rabbitfish females to two injections of HCG at 2 I.U./g BW given 24 h apart was observed. The latency period after hormone injection was inversely related to the initial oocyte size. Minimum initial oocyte size required for spawning without hormone injection was 0.46 mm. HCG induction of spawning was necessary for females with initial oocyte size of ≤0.45 mm. Number of eggs spawned (424000), fertilization rate (96%), and hatching rate (59%) did not differ from those of naturally spawned fish.
    • Article

      Isolation, cDNA cloning, and growth promoting activity of rabbitfish (Siganus guttatus) growth hormone 

      FG Ayson, EGT de Jesus, Y Amemiya, S Moriyama, T Hirano & H Kawauchi - General and Comparative Endocrinology, 2000 - Elsevier
      We report the isolation, cDNA cloning, and growth promoting activity of rabbitfish (Siganus guttatus; Teleostei; Perciformes; Siganidae) growth hormone (GH). Rabbitfish GH was extracted from pituitary glands under alkaline conditions, fractionated by gel filtration chromatography on Sephadex G-100, and purified by high-performance liquid chromatography. The fractions containing GH were identified by immunoblotting with bonito GH antiserum. Under nonreducing conditions, the molecular weight of rabbitfish GH is about 19 kDa as estimated by SDS–PAGE. The purified hormone was potent in promoting growth in rabbitfish fry. Weekly intraperitoneal injections of the hormone significantly accelerated growth. This was evident 3 weeks after the start of the treatment, and its effect was still significant 2 weeks after the treatment was terminated. Rabbitfish GH cDNA was cloned to determine its nucleotide sequence. Excluding the poly (A) tail, rabbitfish GH cDNA is 860 base pairs (bp) long. It contained untranslated regions of 94 and 175 bp in the 5′ and 3′ ends, respectively. It has an open reading frame of 588 bp coding for a signal peptide of 18 amino acids and a mature protein of 178 amino acid residues. Rabbitfish GH has 4 cysteine residues. On the amino acid level, rabbitfish GH shows high identity (71–74%) with GHs of other perciforms, such as tuna, sea bass, yellow tail, bonito, and tilapia, and less (47–49%) identity with salmonid and carp GHs.
    • Article

      Milkfish (Chanos chanos) growth hormone cDNA cloning and mRNA expression in embryos and early larval stages. 

      EGT de Jesus, FG Ayson, Y Amemiya, S Moriyama, S Hyodo, T Hirano & H Kawauchi - Aquaculture, 2002 - Elsevier
      In an attempt to understand growth regulation in milkfish, the milkfish growth hormone (GH) and its cDNA were characterized and the expression of GH mRNA in embryos and larvae was examined by RT-PCR. The milkfish GH was purified from an alkaline extract of the pituitary by reverse-phase high-performance liquid chromatography and detected as an immuno-positive protein with anti-salmon GH serum. The complete sequence of milkfish pre-GH was determined by cDNA cloning and nucleotide sequencing. On the basis of the N-terminal amino acid analysis of the native protein, the pre-GH was found to consist of a signal peptide of 22 amino acids and a mature protein of 188 amino acids. Milkfish GH shows higher amino acid sequence identity with GHs of carps (91–94%) and salmonids (70%) than with GHs of more advanced teleosts (<60%) in good accordance with its taxonomic position in teleosts. It has five half Cys residues, four of which are at positions homologous with those of other known GHs and the extra Cys with those of carp GHs. The molecular weight of milkfish GH was estimated to be 22 kDa, which is comparable to the theoretical value. This suggests that milkfish GH is a simple protein, although it has two potential N-glycosylation sites. Semiquantitative RT-PCR showed that GH mRNA expression was relatively weak in embryos and newly hatched larvae but was already strong in 2-day old and older larvae.
    • Article

      mRNA expression patterns for GH, PRL, SL, IGF-I and IGF-II during altered feeding status in rabbitfish, Siganus guttatus. 

      FG Ayson, EGT de Jesus-Ayson & A Takemura - General and Comparative Endocrinology, 2007 - Elsevier
      Feeding time is a major synchronizer of many physiological rhythms in many organisms. Alteration in the nutritional status, specifically fasting, also affects the secretion rhythms of growth hormone (GH) and insulin-like growth factor-I (IGF-I). In this study, we investigated whether the expression patterns for the mRNAs of GH, prolactin (PRL) and somatolactin (SL) in the pituitary gland, and insulin-like growth factor I and II (IGF-I and IGF-II) in the liver of juvenile rabbitfish (Siganus guttatus) follow a rhythm according to feeding time and whether these hormone rhythms changes with starvation. Hormone mRNA levels were determined by real time PCR. The daily expression pattern for the mRNAs of GH, PRL and SL was not altered whether food was given in the morning (10:00 h) or in the afternoon (15:00 h). The daily GH mRNA expression pattern, however, was affected when food was not available for 3 days. In contrast, the daily expression pattern for IGF-I mRNA reaches its peak at roughly 5–6 h after feeding. This pattern, however, was not observed with IGF-II mRNA. During 15-day starvation, GH mRNA levels in starved fish were significantly higher than the control fish starting on the 9th day of starvation until day 15. The levels returned to normal after re-feeding. In contrast to GH, PRL mRNA levels in starved fish were significantly lower than the control group starting on the 6th day of starvation until 3 days after re-feeding. SL mRNA levels were not significantly different between the control and starved group at anytime during the experiment. Both IGF-I and IGF-II mRNA levels in starved group were significantly higher than the control fish on the 3rd and 6th day of starvation. mRNA levels of both IGF-I and II in the starved fish decreased starting on the 9th day of starvation. While IGF-I mRNA levels in the starved group continued to decrease as starvation progressed, IGF-II mRNA levels were not significantly different from the control during the rest of the starvation period. The results indicate that aside from GH and IGF-I, PRL and IGF-II are likewise involved in starvation in rabbitfish.
    • Book chapter

      Nursery and grow-out culture of Asian seabass, Lates calcarifer, in selected countries in Southeast Asia 

      FG Ayson, K Sugama, R Yashiro & EG de Jesus-Ayson - In DR Jerry (Ed.), Biology and Culture of Asian Seabass Lates Calcarifer, 2014 - CRC Press
      In this chapter, the practices of growing Asian seabass in nursery and grow-out culture systems in selected Southeast Asian countries like the Philippines, Thailand and Indonesia are described.
    • magazineArticle

      Orchestrating the southeast Asian aquaculture towards sustainability: SEAFDEC initiative 

      C Pongsri, FG Ayson, VT Sulit, BO Acosta & N Tongdee - Fish for the People, 2015 - SEAFDEC Secretariat
      Three years after the Philippines became a signatory to the Agreement Establishing the Southeast Asian Fisheries Development Center (SEAFDEC) in January 1968, the Philippine Government submitted a Position Paper during the Fourth Meeting of the SEAFDEC Council in January 1971, formally inviting SEAFDEC to establish a regional aquaculture project in the Philippines. This was anchored on the decision reached during the Third Ministerial Conference for the Economic Development of Southeast Asia in 1968, for SEAFDEC to consider the establishment of a new department to deal with freshwater and brackishwater fish culture, in addition to the already established Research and Training Departments. Subsequently, the Ministerial Conference established a working group of aquaculture experts from the Member Countries to conduct a study on the aquaculture situation in Southeast Asia. Their report which indicated that the new SEAFDEC Department could be established in the Philippines was considered by the Fourth Ministerial Conference for the Economic Development of Southeast Asia in 1969. This led to the series of surveys in the Philippines, conducted by a Survey Mission from the Japanese Overseas Technical Cooperation Agency headed by Dr. Katsuzo Kuronoma, former President of Tokyo University of Fisheries, Japan from 1969 to 1971 to identify the appropriate site of this new Department. Together with counterpart experts from the Philippines, the Survey Mission concluded that the Aquaculture Department would be established in Iloilo Province, Panay Island, Philippines, to undertake aquaculture research in the region, and training of researchers and technicians in aquaculture. Following a conference in September 1972 among representatives from the Philippines and Japan, the Mindanao State University which at that time had already developed the technology for breeding penaeid shrimps, was designated as implementing agency of the Project for the Philippine Government. Although shrimp culture was given priority in the initial project plan, it was also agreed that the new Department could undertake, whenever feasible, the culture of other coastal and brackishwater species, and in a subsequent stage, freshwater fish culture. Based on such recommendations and the commitments of the Governments of Japan and the Philippines to support the operations of the new SEAFDEC Department, the Sixth Meeting of the SEAFDEC Council in July 1973 in Kuala Lumpur, Malaysia agreed to establish the Aquaculture Department in Iloilo, Philippines, adopted the corresponding Plan of Operation and Program of Work, and approved the appointment of Dean Domiciano K. Villaluz as the first Department Chief. True to its word, the Aquaculture Department has since then been pursuing programs on sustainable development and responsible stewardship of aquaculture resources in Southeast Asia through research and promotion of appropriate aquaculture technologies and socio-economic strategies relevant to the sustainability of the aquaculture industry in the region.
    • magazineArticle

      Potential and prospects of southeast Asian eel resources for sustainable fisheries and aquaculture development 

      S Siriraksophon, FG Ayson & VT Sulit - Fish for the People, 2014 - SEAFDEC Secretariat
      The world demand for river eels has been increasing mainly because of the market expansion of some delicacies such as the kabayaki (broiled eel with sweet soy sauce) in East Asia. While most of the world’s eel production is derived from aquaculture, it should be noted that eel aquaculture is still dependent on the natural resources. As techniques for the full-life cycle aquaculture of eels have not yet been fully developed for commercial use, the eel aquaculture industry is still solely dependent on wild resources for seed stocks. However, the natural resources had been confronted with various factors that could possibly create negative impacts on the eel resources including habitat alteration, overexploitation, climate change, pollution, and incidence of diseases. Thus, concerns on the sustainability of various eel species in the world have increased in recent years. It should be reckoned that the European and American eels are already threatened to certain degree by pollution and damming (or the construction of dams that prevent their migration to freshwater bodies) leading to almost “close to collapse” of the European eel resources. This situation prompted CITES to list the European eel (Anguilla anguilla) in CITES Appendix II in 2009 and accordingly, trade restrictions of the European eel and its products came into effect. In Southeast Asia, it is known that aquaculture and inland capture fisheries of eel are practiced but data and information on the total production of eel in the region remain very minimal. In this regard, the Southeast Asian countries have been encouraged to report their respective eel production to SEAFDEC in order that the status and trend of the region’s eel resources could be established and the statistics could be appropriately reflected in the Fishery Statistical Bulletin of Southeast Asia produced yearly by SEAFDEC. Meanwhile, in an effort to conserve the eel resources in Southeast Asia, SEAFDEC recently launched a project on Conservation, Management and Sustainable Utilization of Eel Resources in Southeast Asia with funding support from the Trust Fund for SEAFDEC of the Fisheries Agency of Japan.
    • Book chapter

      Reproductive biology of the Asian seabass, Lates calcarifer 

      EG de Jesus-Ayson & FG Ayson - In DR Jerry (Ed.), Biology and Culture of Asian Seabass Lates Calcarifer, 2014 - CRC Press