213 research outputs found
Degeneration of the olfactory epithelium in the Anguilid eels by hormone treatment
No full textWhile the olfactory cue hypothesis has been proposed for spawning migration of silver eels, it has been shown that olfactory cells and associated mucus cells degenerate in male and female eels after hormonally induced sexual maturation. However, the degeneration of the olfactory organ could be a real event in the sequence of maturation, or may be an unnatural side effect of the hormone treatment itself. We morphologically and histologically examined the olfactory rosettes of hormone-untreated and hormone-treated (mixture of hCG and PG) giant mottled eel (Anguilla marmorata) and Japanese eel (A. japonica). The olfactory rosette from all the hormone-treated specimens significantly degenerated at various degeneration levels even in sexually immature specimens, indicating the side effect of the hormone-treatment. However, a sexually immature non-hormone treated female A. marmorata (87.4 cm TL, 199.4 g BW, at less advanced maturity) had slightly degenerated olfactory rosette. Further studies should focus on conducting natural degeneration of the olfactory rosette during the sexual maturation in tropical eels
Comparison of Nannochloropsis Oculata productions cultivated in two different systems: outdoor red tilapia (Oreochromis Sp.) culture tank and indoor pure culture
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Studies on the enhancement of early larval survival of groupers Epinephelus sp.
No full text The kelp grouper (Epinephelus bruneus) and tiger grouper (Epinephelus fuscoguttatus) are among the important targeted aquaculture species in temperate and tropical water respectively in the Asian region. Nevertheless, reliable of large-scale production of both groupers is greatly hindered by the high mortality at early larval stage. It was reported that larval survival rates for the kelp grouper and tiger grouper were only 0.3-37.0% and 0.02-4.0%, respectively. Therefore, two independent approaches were introduced in this study for the enhancement of early larval survival of both groupers.application/pdfdepartmental bulletin pape
The effects of long jack, Eurycoma longifolia on sperm quality and quantity of African catfish, Clarias gariepinus
No full textThe experiment was to study the effects of long jack, Eurycoma longifolia through the sperm quality and quantity of African catfish, Clarias gariepinus. Mostly farmers are using hormone to induce the reproduction in these fishes especially C. gariepinus. For expanding interest in C. gariepinus, there was expanded exertion in the improvement of method for production of fish in hatchery. Thus, the present study was an alternative to improve the production of C. gariepinus. In the present study, two diets with crude protein of 40 % were formulated with different supplementation levels of E. longifolia powder; with no supplementation of E. longifolia (LJ0) and the supplementation of 5 % E. longifolia (LJ5). Eight males of C. gariepinus were randomly distributed into two fibre tanks (2×2×1.5 m) with four fish per tank. The tank was contained green water (pH≈ 7.2, dissolved oxygen≈ 5.3 mg/L, temperature≈ 27.20°C). C. gariepinus were fed at 3% of body weight twice a day for a period of 30 days. The diet in LJ5 had significantly higher in sperm counts (12085.33±286.71x104 sperm/ml), milt volume (0.38±0.04 ml) and motility duration (24.11±0.96sec). While the result for diet in LJ0 in sperm count, milt volune and motility duration were 10014.67±273.76x104sperm/mL, 0.21±0.06 ml and 12.67±0.58sec. However, significant differences were not observed in the body weight gained, total length, specific growth rate and feed conversion ratio (FCR) among the two treatments. Besides, the results were showed E. longifolia possess promising pro-fertility which can be exploited in fish seeds production and 50 g/kg of E. longifolia based diet could give satisfactory and efficient result on the sperm quality and quantity of C. gariepinus
Reproductive Ecology of the Java Rabbitfish, Siganus javus, in the Southern South China Sea
No full textFish reproductive biology influences their life history and can impact their vulnerability to fisheries; therefore, for sustainable management and development, a proper understanding is crucial. Reproductive biology, including maturation, spawning season, fecundity, and sex ratio, was examined throughout the year in the Java Rabbitfish, Siganus javus, in the southern South China Sea. This study is the first to examine reproductive traits by collecting a total of 339 S. javus specimens monthly from September 2017 to August 2018 through detailed gonad histology. The spawning season of female S. javus was mainly restricted to July, August, October, and December, whereas male fish were found to spawn throughout the year. Inter-species variations in the spawning season were observed within the genus, which is influenced by interspecific spawning strategies and regional environmental factors. The sex ratio close to 1:1 suggests that the fish population is in equilibrium in the region. The fecundity of S. javus ranged from 1.8 × 105 to 12 × 105, which was similar to that of other species in Siganus, suggesting less inter- and intra-species variation in fecundity within the family. The middle maturation stage was absent throughout the year, probably due to the different habitat uses during their life history. Reproductive biology might influence other biological aspects, such as migration and behaviour in the fish
Embryonic and larval development of backcrossed hybrid grouper between TGGG (Epinephelus fuscoguttatus x E. lanceolatus) and giant grouper (E. lanceolatus)
No full textThis study examined the embryonic and larval development of TGGGxGG, the backcrossed hybrid grouper tiger grouper (TG) x giant grouper (GG) (Epinephelus fuscoguttatus x E. lanceolatus) and giant grouper (E. lanceolatus), including its morphology, sensory organ development, and behavioural changes. A 15 kg matured hybrid grouper TGGG female and an 80 kg male GG were selected. The findings showed fertilization and hatching rate were recorded at 70.65% and 39.51% respectively and egg size was 850 ± 40 μm. Hatching occurred at 16:43 h after fertilization (hAF) under 29.3C◦ and the size of newly hatched larvae was 1.336 ± 0.118 mm and grew up to 11.95 mm at 50 dAH. Larvae initiated its first feeding at 48 hAH. Behaviourally, newly hatched larvae were seen passive with only up-and-down behaviour but drastically shifted to active feeding at 4 dAH onwards. TGGGxGG larvae show positive phototaxis at 48 hAH when their eyes are fully pigmented and positive rheotaxis at 4 d AH when pectoral fins develop. Free neuromast was distributed on the head parts of newly hatched larvae and its number increased linearly with larval growth until 25 dAH. The new backcrossed hybrid TGGGxGG has similar embryogenesis, larval and sensory organ development as other pure and hybrid groupers. However, slow growth was seen in backcrossed TGGGxGG, hence enhancement of its growth should be further examined
Natural spawning, embryonic and larval development of F2 hybrid grouper, tiger grouper Epinephelus fuscoguttatus × giant grouper E. lanceolatus
No full textAbstract This study aims to reveal the first report of the natural spawning of F1 hybrid grouper (TGGG), a crossbreed between the tiger grouper, Epinephelus fuscoguttatus × giant grouper, E. lanceolatus, since its first production in 2006. This marks the completion of its full cycle after a 10-year period. In order to establish a seed rearing protocol for a novel F2 hybrid TGGG, natural spawning, embryonic and larval developments were thoroughly observed. Five batches of natural spawning were recorded with an average of 1.50–15.3 kg eggs collected, while fertilization and hatching rates were recorded at 85.3–97.6%, and 63.0–98.3%, respectively. F2 larvae hatched out at 17:50 hours with an average body size of 1.74 ± 0.01 mm, and a yolk sac volume of 0.85 ± 0.197 mm3. The first feeding was initiated 3 days after hatching, which coincided with the onset of functional feeding apparatus and active swimming behavior. Larval dorsal and pelvic spines were formed at 6 days AH coupled with dynamic feeding activity, as more food was found in the digestive tract. Meanwhile, the F2 hybrid grouper shifted habitat from pelagic to benthic as early as 25 days AH, and entered a juvenile stage at 35 days AH, attaining a skin coloration similar to that of the F1 juvenile. This study concluded that naturally spawned eggs of F2 hybrid TGGG were exceptionally high in quality, although larvae were small and fragile, and performed vigorous feeding activities and cannibalistic behavior. Thus, these findings can serve as primary data to further develop the optimal rearing protocol to enhance the overall rearing performance
Eggs, larval morphology development and behavioral changes of jade perch (scortum barcoo) larvae
No full textThis study examined the embryonic development of Jade perch (Scortum barcoo) during the early larval stage, emphasizing morphology, sensory organ development, and behavioral changes. Artificial reproduction was conducted using one mature female (1.0 ± 0.0 kg) and two mature males (1.0 ± 0.8 kg) through hormone-induced spawning. The fertilization and hatching rates were recorded as 83.4 ± 0.45％ and 86.4 ± 0.78% respectively, and fertilized egg size was 2.73 ± 0.3 mm. Hatching occurred at 20:20 hours after fertilization (hAF) under 27.3 ± 0.7 ℃ and the size of newly hatched larvae was 2.79 ± 0.05 mm, growing up to 4.73 ± 0.07 mm by 90 hours after hatching (hAH). Morphological developments were observed as follows: eye and fin formation at 6 hAH, noticeable pigmentation at 30 hAH, mouth opening at 36 hAH, jaw movement at 42 hAH, and anus opening at 60 hAH. Sensory organs development was observed as follows: lens formation and inner ear formation at 6 hAH, eye pigmentation and olfactory pit formation at 30 hAH. Behavioral changes were observed as follows: onset of vertical swimming at 12 hAH, onset of horizontal swimming at 18 hAH, with larvae showing positive phototaxis and rheotaxis at 30 hAH, and first feeding starting at 72 hAH. This study concludes that Jade perch undergoes normal development, and these primary data can be used to establish a rearing protocol to further enhance the overall growth performance in captivity
Annotated translation of specific chapters of the book "Porqué fui Presidente" by Gustavo Noboa Bejarano.
No full textThe following annotated translation was carried out with the purpose to let people to know more about the Ecuadorian political history. This piece of translation contains specific facts regarding one of the worst economic and political crisis of the country dated in 1999 – 2000 which included the holiday bank and the freezing of bank deposits followed by the dollarization. The book “Porqué Fui Presidente” narrates the circumstances in which the decisions of the country were taken and also by whom. It mentions the
reaction of the Ecuadorian people and the participation of the Ecuadorian army in the overthrown of then President of Ecuador, Jamil Mahuad, and how the Vice President, Gustavo Noboa Bejarano, assumed the position as President of Ecuador. All the process led by the political instability is narrated from the point of view of the author, Gustavo Noboa, who includes details of his experience. The book which has only been presented in Spanish contains political and financial terminology Ecuador had during those years. The rendering of this book will represent an opportunity for other authors to let their work be recognized and contribute to their political culture
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