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Volume 58, Issue 4
Displaying 1-15 of 15 articles from this issue
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Original Papers
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Eitaro Sawayama, Motohiro Takagi2010 Volume 58 Issue 4 Pages 441-446
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSReversed abnormality is one of the common deformities in flat fish species. To identify the cause of reversed abnormality in Japanese flounder from a hatchery population, we evaluated genetic variability and parentages in reversed individuals using microsatellite DNA markers. Seventeen parents were used for the seed production, and 52 normal and 49 reversed individuals were sampled at 96 day-post-hatched. There were no differences in heterozygosity and allele frequencies between normal and reversed individuals. The parentages of all specimens used in this study were identified by microsatellite DNA data. Parentage analysis indicated that normal individuals were generated from 7 female and 5 male parents, and 14 parental pairs were observed. Reversed individuals were generated by 7 female and 7 male parents, and 18 parental pairs were observed. One female parent significantly generated a higher rate of reversed individuals compared to the other female parents. These results support the fact that reversed individuals identified in a hatchery population had arisen via environmental effects, although some were due to genetic and/or maternal effects.View full abstractDownload PDF (255K) -
Ken-ichi Yamamoto, Takeshi Handa, Toshiaki Matsubara2010 Volume 58 Issue 4 Pages 447-451
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSChanges in the ventilation volume and the amount of oxygen uptake associated with feeding Chaetoceros glacilis were examined in the pearl oyster Pinctada fucata martensii. The ventilation volume began to increase at feed densities of 80-97 cells/ml and the increased volume persisted at densities of 119-15,324 cells/ml for 8 hours or more. However, the volume changed repeatedly at densities of 33,021 cells/ml or more. At a densities of 10,000 cells/ml, the volume increased to 2.8 times that without feeding. Nevertheless, the amount of oxygen uptake was not affected by the feed, and was approximately held constant.View full abstractDownload PDF (295K) -
Ken-ichi Yamamoto, Takeshi Handa, Toshiaki Matsubara2010 Volume 58 Issue 4 Pages 453-457
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSTo clarify the effects of the procedures for nuclear insertion on physiological function in the pearl oyster Pinctada fucata martensii, ventilation volume (Vg) and amount of oxygen uptake (Vo2) were measured before and during feeding with the Chaetoceros gracilis in the non-treated group (NTG), the treated group (Sitate sagyou group, TG), artificial spawning by bubbling ozone-gas group (SOG), and operation of nuclear insertion group (ONG). NTG and TG showed more of the same Vg, and SOG and ONG exhibited nearly half of Vg of NTG. TG, SOG and ONG indicated the similar Vo2, which were approximately half of Vo2 of NTG. These results suggested that artificial spawning by bubbling ozone-gas and operation of nuclear insertion does not influence the oxygen uptake, but that the artificial spawning affect the ventilation.View full abstractDownload PDF (561K) -
Kei’ichiro Iguchi, Hiroyuki Sakano, Hirohiko Takeshima2010 Volume 58 Issue 4 Pages 459-463
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSAyu Plecoglossus altivelis is migratory fish that experiences estuarine backish water in the early life stages. The recent decline in the abundance of populations that ascend into rivers is of concern for freshwater fisheries. The present study aims to elucidate the starving process that determine the early success of ayu hatchlings under the variable environmental conditions in terms of salinity and water temperature. Transition from endogenous feeding state to irrecoverable starved state occurred at the time when the yolk-sac became unnoticeable, a couple of days before being consumed to death accordingly to the water conditions. RNA/DNA revealed that high salinity and high water temperature together required more cost for maintenance including osmoregulation, resulting in the acceleration of yolk depletion and led to reduced metabolic activity. Seawater with a high temperature is considered to have an adverse effect on the survival of newly hatched larvae.View full abstractDownload PDF (432K) -
Tadashi Isshiki, Giannakou Eleni, Yutaka Ueta, Taizou Nagano2010 Volume 58 Issue 4 Pages 465-471
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSSusceptibilities of the oblong rockfish Sebastes oblongus to viral hemorrhagic septicemia virus (VHSV) were examined by experimental infections via an intramuscular route with an isolate KRRV-9822 from Japanese flounder Paralichthys olivaceus. Mortalities for these fish injected with doses of 103.3, 105.3 and 107.3 TCID50/fish occurred rapidly, and took 10, 5 and 3 days to reach 90, 100 and 100%, respectively, compared with 10 days to reach 100% even for Japanese flounder injected with 107.3 TCID50/fish. The cumulative mortalities for oblong rockfish maintained at 15 and 20°C for 16 days following a viral injection of 102.8 TCID50/fish were significantly different, being 70 and 13%, respectively. When oblong rockfish, which had survived a VHSV natural outbreak, received a viral injection of 102.8 TCID50/fish, the mortality for 16 days at 15°C was 17%. In comparison, other oblong rockfish, which were previously naïve to a VHSV infection, had a 70% mortality following the same viral infection. These results revealed that the viral susceptibility of oblong rockfish is much higher than that of Japanese flounder and it depends on lower temperature. In addition, it is likely that oblong rockfish develops a protective immunity against VHSV infection.View full abstractDownload PDF (164K) -
Yushi Shimada2010 Volume 58 Issue 4 Pages 473-479
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSIn order to investigate a possibility to be a culture strain of the laver Porphyra yezoensis, the physiological and morphological characters were compared between three wild strains, S1, S2 and S3, collected from the Hokkaido waters and the culture strain, U-51. The following seven characters were examined: growth rate, blade length/width ratio, shape of thallus, optical coloration of thallus, readiness of monospore formation, readiness of generative cell formation, and discoloration under low nutritional condition. The optical color of S2 and S3 was deeper in red and black than U-51, and S3 showed higher growth rate than U-51. The growth rate, blade length/width ratio and readiness of monospore formation were different among the wild strains. The wild P. yezoensis strains examined in this study showed morphological and/or physiological diversities, and some characters were considered to be suitable for the laver culture.View full abstractDownload PDF (390K) -
Takeshi Yamamoto, Kenji Kawai, Syun-ichirou Oshima2010 Volume 58 Issue 4 Pages 481-489
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSNecessary condition to perform experimental infection with Tenacibaculum maritimum was investigated. A shaking culture of the bacterium for 48 h was used to infect Japanese flounder Paralichthys olivaceous. First, three infection methods, intraperitoneal (IP) injection and two immersion methods were compared. IP injected flounder with T. maritimum at doses of 104.82 or 104.92 CFU/fish did not exhibit high mortality or typical symptoms. “Immersion and dilution method”, where immersion-infected fish at doses 105.81 or 105.91 CFU/ml were successively reared in the same tank supplying fresh rearing water, resulted in higher mortality than “immersion and transfer method”, where immersion-infected fish were transferred to another rearing tank. Using immersion and dilution method, stable mortality occurred between 17°C and 26°C but not below 17°C or over 26°C. Too much diluted bacterial culture with sea water did not yield high mortality even when the immersion water contained enough bacterial concentration. This suggests extracellular substance contains virulence factor. T. maritimum was detected on the body surface of infected fish but not in the gills or kidney. In conclusion, the immersion and dilution method is an adequate infection method for this disease. In order to achieve satisfactory infection, the precise management of water temperature and the dilution rate of bacterial culture are required.View full abstractDownload PDF (351K) -
Yutaka Haga, Toshihito Naiki, Youhei Tazaki, Takayuki Takebe, Kazunori ...2010 Volume 58 Issue 4 Pages 491-499
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSPacific bluefin tuna (PBT) Thunnus orientalis larvae at 18 days post hatching (dph) (total length; 14.8±2.1 mm) were fed for 6 days on fertilized eggs, yolk-sac larvae of spangled emperor Lethrinus nebulosus at 1 or 3 dph, or a microdiet. After feeding, growth performance, feeding incidence and survival were evaluated. Feeding 3 dph spangled emperor yolk-sac larvae improved growth of PBT compared to the other feeds. Crude protein and essential amino acids contents in the 3 dph spangled emperor yolk-sac larvae were higher than those of the spangled emperor at 1 dph. This result suggests that yolk-sac larvae of spangled emperor at 3 dph are suitable for PBT larvae and improved growth would be due to their higher protein and essential amino acids contents. It was also observed that 40% of PBT larvae fed the microdiet, suggesting that casein peptide based microdiet is acceptable for PBT.View full abstractDownload PDF (169K) -
Yosuke Tanaka, Hiroshi Minami, Yuka Ishihi, Kazunori Kumon, Takeshi Eb ...2010 Volume 58 Issue 4 Pages 501-508
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSIn mass culture of Pacific bluefin tuna Thunnus orientalis, a marked growth variation is frequently observed after yolk-sac larvae of other species start feeding at 6 - 7 mm in body length (BL), and the growth variation of tuna larvae is a factor leading to the prevalence of cannibalism. In order to examine the prey utilization in relation to the growth variation, stable isotope ratios (δ13C and δ15N) were analyzed for individual larvae. A prey switch experiment was conducted under two different feeding regimes: a group fed rotifers and Artemia nauplii (plankton fed group), and a group fed yolk-sac larvae (fish larvae fed group) from 15 days after hatching (7.38 mm BL). The fish larvae fed group showed significantly higher growth than the plankton fed group. Changes in the δ13C and δ15N of the fish larvae fed group were expressed as an exponential models and showed different patterns from those of the plankton fed group. The δ15N of fast growing tuna larvae collected in the actual mass culture tank after the feeding of yolk-sac larvae were significantly different from those of the slow growing larvae, indicating that prey utilization of tuna larvae were different corresponding to their growth.View full abstractDownload PDF (319K) -
Takakiyo Oonuki, Nobuhiro Suzuki, Nobuhiko Akiyama2010 Volume 58 Issue 4 Pages 509-516
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSA new Palaemonid shrimp distribution was found for the first time in the record in Japan in a pond in Matsushima town, Hamamatsu city, Shizuoka Prefecture, Japan. It was identified, as a result of a morphological examination, to be Palaemonetes sinensis. P. sinensis can be distinguished from indigenous Palaemonid shrimp by absence of the palp.
The habitat is isolated from the sea and larva of P. sinensis has an ability to grow under freshwater. It is suggestive that the species has been transported either intentionally or unintentionally, but not by natural causes.
In order to acquire basic knowledge about the life history, a female reproductive cycle was investigated from October, 2005 to September, 2007. Oogenesis of P. sinensis was classified in to six stages for this study: chromatin nucleolus, perinucleolus, yolk granule, primary yolk, secondary yolk, and tertiary yolk stage. Based on these classifications and histological features of ovaries, ovarian maturity was classified into four phases: multiplication, vitellogenic, maturation, and ovulation phases. The maturation phase and ovigerous female appeared between May and September. Moreover, it was suggested that multiple spawning at one reproductive season was confirmed from the relationship between the development of ovigerous egg and ovarian maturity.View full abstractDownload PDF (770K) -
Hiromi Ohta, Kahori Arita, Kiyoshi Isowa, Takashi Ishikawa, Hideo Aoki2010 Volume 58 Issue 4 Pages 517-523
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSJapanese pearl oysters are widely cultivated by artificial fertilization using gametes obtained from the ovary and testis. Using the gametes from the Japanese pearl oyster, we developed a method for conducting small-scale artificial fertilization tests in a 24-well microplate. Following induction of germinal vesicle breakdown (GVBD), we inseminated 20,000 eggs in 2.0 ml seawater in a single well of a microplate. The highest fertilization rates were obtained using a testicular semen volume of 1.25μl when the concentration of NH3 in seawater was 0.75 mM during insemination. Changes in contact time (the time from commencement of insemination to rinsing the eggs) from 3 to 60 min did not affect the fertilization rate. However, a contact time of >12 min was necessary to ensure consistency in contact time among the 24 wells.View full abstractDownload PDF (157K)
Short Papers
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Hidetoshi Saito, Satoshi Ikeura, Koichiro Kawai, Hiromichi Imabayashi2010 Volume 58 Issue 4 Pages 525-527
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSField experiments were made at four sampling stations of Mitsu Bay, Hiroshima Prefecture to examine survival rate of Japanese littleneck clam Ruditapes philippinarum released with and without cover nets which protect from predators. The clams were almost disappeared within one month at experimental flats without cover nets of all sampling stations. The clams were showed 26-32.5% of survival rate at protection of small mesh (4×4 mm) net of stns.1, 2 after ten months, whereas they were not survived at stns. 3, 4. Survival rate of the clam seemed to be affected by predators such as moon snail Glossaulax didyma and black sea bream Acanthopagrus schlegeli.View full abstractDownload PDF (316K) -
Shinya Mizuno, Makoto Hatakeyama, Miyuki Nakajima, Kazuaki Naito, Tats ...2010 Volume 58 Issue 4 Pages 529-531
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSWe examined relationships between rearing conditions and health parameters, carcass adenosine triphosphate (ATP) content and ATP synthase transcript (AST) level, using chum salmon fry in two hatcheries to demonstrate appropriate rearing conditions. The standard values of ATP content (<21.0 pmol/g body weight) and AST level (>4.34 pmol competitor/μg total RNA), which reflect health, were in the range of <30 kg/m3 at rearing density and >8 mg/l at dissolved oxygen concentration (DO). Our results suggest that physiologically appropriate rearing conditions for culture of chum salmon fry were <30 kg/m3 at rearing density and >8 mg/l at DO.View full abstractDownload PDF (123K) -
Chutima Hanjavanit, Kwanprasert Panchai, Shinpei Wada, Osamu Kurata, ...2010 Volume 58 Issue 4 Pages 533-537
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSArtificial infection with the fungi Saprolegnia diclina BKKU 0506 and Achlya bisexualis BKKU 0616 was induced in the platyfish (Xiphophorus maculates) via exposure to zoospores following artificial injury by scale removal and net-shake or “ami-momi” treatment. The results suggested that ami-momi treatment, but not scale removal, could be used to establish severe fungal infection in small freshwater tropical fish as well as salmonids.View full abstractDownload PDF (211K)
Abstracts
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M Matsuyama2010 Volume 58 Issue 4 Pages 539-560
Published: December 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSDownload PDF (679K)
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