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Volume 60, Issue 4
Displaying 1-13 of 13 articles from this issue
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Original Papers
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Kyosei Noro, Yasunori Sakurai2012 Volume 60 Issue 4 Pages 429-443
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSMigration, distribution and growth of Enteroctopus dofleini (Wülker, 1910) were investigated in waters adjacent to the Tsugaru Strait by release of tagged specimens and comparison with those obtained from fisheries recaptures. A total of 1,190 individuals were recaptured between 1986 and 2007. The initial mean body weight of recaptured specimens at their release was 1.6±0.7 kg (range: 0.1-7.7 kg); mean body weight at recapture was 5.9±4.6 kg (range: 0.7-37.0 kg); and mean elapsed days between release and capture was 174±132 days (range: 2-1,062 days). In terms of horizontal migration, the rate of recapture at the same release station (or in a nearby locality) was high; and 13.5% of individuals obtained on the Honshu side crossed the Tsugaru Strait and migrated to their site of recapture on the Hokkaido side. Considering vertical distribution, octopuses were recaptured from depths of 2 m to 350 m, migrating to deeper areas with increasing growth during the summer. The factor of deeper distribution in summer is affected by the high sea water temperature at this time of year in the Tsugaru Strait. The growth rate was lower in larger specimens of both sexes. From measurements of body weight and tagging results, the specimens were classified into four groups, reaching mature size in 2, 3, 4 or 5 years.View full abstractDownload PDF (3849K) -
Shin-ichiro Abe2012 Volume 60 Issue 4 Pages 445-449
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSHabitat preference of ayu Plecoglossus altivelis was examined using four replicate artificial streams each with areas of even and uneven streambed. Ayu were introduced into each stream by increasing the number of fish cumulatively from 5 to 40 individuals. When 5, 10, 20 and 30 fish were released, the number of fish was greater in the area with an uneven streambed, whereas the difference was not significant when the streams were stocked with 40 fish. These results indicate that ayu use uneven streambed habitats preferentially and thus river modification leading to even streambeds results in a degradation of habitat quality for ayu.View full abstractDownload PDF (437K) -
Hideo Aoki, Shinji Tanaka, Takashi Atsumi, Hisayo Abe, Takayuki Fujiwa ...2012 Volume 60 Issue 4 Pages 451-457
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSShell-closing strength (SCS)-the load required to open the valves-is a useful indicator of the physiological and nutritional conditions in the Japanese pearl oyster Pinctada fucata. We investigated the relationship between SCS and nacre thickness (an indicator of pearl quality) to assess the suitability of SCS as an indicator of pearl-deposition ability in this species. Japanese pearl oysters were implanted with a nucleus and a piece of the mantle tissue from donor oysters. Recipient oysters were cultured and pearls were harvested 4 and 6 months after the operation. The relationship was determined between SCS and nacre thickness. There was a significant positive correlation between SCS and nacre thickness on both the 4th and 6th month after nucleus insertion (r = 0.52-0.64). Moreover, oysters with higher SCS had higher soft-tissue nutrient content and relative adductor muscle weight, suggesting they were in good health. Our results suggest that SCS is associated with calcium metabolism in pearl oysters and may serve as an indicator to select pearl oysters with good better physiological state that produce thicker nacre-quality pearls.View full abstractDownload PDF (840K) -
Shunji Amano, Nobuhiro Suzuki, Hiroyuki Matsunari, Yasuro Iwashita, Ta ...2012 Volume 60 Issue 4 Pages 459-467
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSTo examine the effect of soybean meal and taurine on the histology of the hepatopancreas in red sea bream Pagrus major, a feeding experiment was conducted. Three diets, control fish meal-based diet (FM), defatted soybean meal based non-fish meal diet (NFM) and NFM containing 0.25% taurine (NFM+T), were fed to red sea bream (approximately 9 g in BW) for 6 weeks and hepatopancreatic histology was investigated. In fish fed diet NFM, hepatocytes were atrophied, and atrophied adenocytes, degenerated zymogen granules and red blood cells were observed in exocrine portion of the pancreas. Furthermore, a certain improvement of these degenerative features were found in NFM+T fed fish. The results suggest that taurine supplementation will be effective for mitigation of histological degeneration in the hepatopancreas by feeding NFM.View full abstractDownload PDF (869K) -
Erina Fujiwara-Nagata, Mitsuru Eguchi2012 Volume 60 Issue 4 Pages 469-474
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSIn this study, we assessed the utility of a quantitative loop-mediated isothermal DNA amplification (LAMP) assay for Flavobacterium psychrophilum in natural river water. Direct addition of serial dilutions of DNA standard to the DNA samples extracted from each river water enabled the precise estimation of the amount of F. psychrophilum-DNA despite the presence of inhibitors. This is a novel method for attenuating the inhibitory effects of unknown substances in natural water samples.View full abstractDownload PDF (373K) -
Naoki Yoshikawa, Thamootharan Mammaran, Elvin Michael Bavoh, Abduhl ...2012 Volume 60 Issue 4 Pages 475-483
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSThe primitive flatfish Psettodes erumei is an excellent species to study evolutionary mechanisms of asymmetrical metamorphosis, because it exhibits dimorphism in eye-sidedness. In this study, we collected basic information on the gonadal development to establish it as an experimental system. Specimens were purchased from November 2009 to October 2010 at a fish market in Kota Kinabalu, Malaysia. Specimens less than 30 cm standard length (SL) were almost exclusively males or had an undetermined sex, and those over 30 cm SL were females. Histologically, no premature ovarian tissues were found in testes, suggesting that the probability of sex change from male to female is low. Sperm were found in all testis-examined males (larger than 18.7 cm SL or a gonadosomatic index, GSI, over 0.1) collected from November to May. Males with GSI over 0.1 were present throughout the year. Oocyte development was asynchronous. Mature oocytes were found in females with a GSI over 6. Seasonal changes in GSI were not seen in females. These results indicate that artificial fertilization may be possible throughout the year, using wild fish 20-30 cm SL as mature males and wild fish larger than 30 cm SL with a GSI value >6 as candidate mature females.View full abstractDownload PDF (564K) -
Janice Alano Ragaza, Shunsuke Koshio, Roger Edward Mamauag, Binh Th ...2012 Volume 60 Issue 4 Pages 485-494
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSThe experiment was conducted to determine optimal dietary inclusion level of red algae Eucheuma denticulatum in diet of red sea bream Pagrus major. Four isonitrogenous and isolipidic soy protein concentrate (SPC) diets and one fishmeal (FM) diet (D1) were prepared with red algae supplementation levels of 0% (D2), 3% (D3), 6% (D4), and 9% (D5). Triplicate groups of fifteen juveniles (3.90±0.05 g, mean±SEM) were stocked in 100-l polypropylene tanks and fed twice a day to apparent satiation level for 56 days. The study demonstrated that fish fed D3 grew faster than those fed diets 2, 4, and 5, although growth was not significantly different from fish fed D1. Muscle total amino acid and whole body proximate composition of fish were not altered by dietary treatments. Red algae supplementation improved hemoglobin (Hb), glutamyl oxaloacetic transaminase (GOT), and lowered reactive oxygen molecules (d-ROMs). E. denticulatum can be efficiently absorbed and utilized by red sea bream, and optimal dietary supplementation level is at 3% of diet.View full abstractDownload PDF (184K) -
Hoji Iwatani, Koji Inoue, Yoshio Takei, Hiroki Abe2012 Volume 60 Issue 4 Pages 495-501
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSFourspine sculpin (Cottus kazika), a euryhaline and catadromous teleost, was artificially hatched and reared in seawater (SW). Some one-year-old fish had been reared in fresh water (FW) were transferred to SW, and further reared in FW or SW for four months. Free amino acids in the skeletal muscle of wild fish and those reared in FW or SW were compared at the stages of downstream migration (December) and upstream migration (August). The results showed that the skeletal muscle of the sculpin contains large amounts of glycine followed by alanine and lysine, and the lysine content was lower but alanine content was higher in SW-reared fish than in FW-reared fish in both seasons. It seems that season of migration and the actual changes in environmental salinity affect amino acid contents of the skeletal muscle. In addition, total free amino acids in the skeletal muscle of wild fish and those reared in FW or SW showed no significant difference but the muscle taurine content was higher in wild fish compared with cultured ones. Taurine content, however, largely decreased in SW-acclimated fish at the stages of upstream migration, Therefore taurine in the skeletal muscle may be complementary to other amino acids to maintain total amino acids in the skeletal muscle of this species.View full abstractDownload PDF (415K) -
Yasuro Iwashita, Nobuhiro Suzuki, Shunji Amano, Akiko Shiragane2012 Volume 60 Issue 4 Pages 503-510
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSReproductive size of the golden mussel Limnoperna fortunei (246 specimens) in the Yahagi River, Aichi Prefecture, Japan was studied by gonad histology. The rate of mature and spawning individuals accounted for 83.7% of the total mussels collected from July to September 2010. Sexual differentiation began at the shell length of about 5 mm. Minimum shell length of mature stage was 9.6 mm in female and 5.8 mm in male, and then the shell length of spawning stage was 10.9 mm in female and 9.4 mm in male, respectively. Moreover, the reproductive shell length, including mature and spawning stages, was considered 21 mm in female and 20 mm in male.View full abstractDownload PDF (901K)
Short Papers
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Tadashi Imai, Yasutoshi Yoshiura, Kenji Sakae, Takashi Katayama, Yoshi ...2012 Volume 60 Issue 4 Pages 511-513
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSWe investigated prevention of adhesion to experimental tools of tiger puffer Takifugu rubripes eggs. Eggs stuck fast to the tip and the inner wall of glass pipettes, but egg adherence was inhibited by the use of polyethylene pipettes. Eggs stuck to watch glasses as well as glass pipettes. On the contrary, eggs showed minimal attachment to watch glasses covered with wrap of seven materials. Therefore, this method using a polyethylene pipette and glassware covered with wrap prevents adhesion of tiger puffer eggs.View full abstractDownload PDF (363K) -
Yoshitomo Nagakura, Tsutomu Noda2012 Volume 60 Issue 4 Pages 515-517
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSHatchery-reared Pacific herring Clupea pallasii larvae and juveniles [56 days after hatching; mean standard length (SL) 24.4 mm] were transfered from 20 kl rearing tank to a net cage (2.0×3.0×1.5 m; opening size, 1.3 mm) in 150 kl tank by fingerling transfer pump with hose 50 mm in diameter (2.0 kl / hour). Cumulative mortality at 6, 24 and 48 hours after transfer were 10%, 31% and 34%, respectively, and mortality reduced markedly 24 hours after transfer. Cumulative mortality decreased with the body size and cumulative mortality at 48 hours after transfer of the fish less than SL 20 mm, SL 21-24 mm, SL 25-28 mm and more than SL 29 mm were 100%, 53%, 12% and 0%, respectively. All fish of less than SL 20 mm died and all fish of more than SL 29 mm survived within 48 hours after transfer. These results indicate that fish of more than SL 29 mm can be transferred by this method without affecting survival after transfer.View full abstractDownload PDF (386K) -
Chia-Hui Chen, Kazuyuki Sagara, Shiro Itoi, Haruo Sugita2012 Volume 60 Issue 4 Pages 519-521
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSThe diversity and density of sulfate-reducing bacteria (SRB) in the intestinal tract of spotnape ponyfish Leiognathus nuchalis were determined by the clone library analysis and real-time PCR technology targeting dsrA, respectively. As a result, SRB was detected in one of five specimens of spotnape ponyfish with a density of 3.3×108 copies/g. Thirty-two clones in the library were composed of four families of SRB including Desulfobacteraceae (6 species, 13 clones), Desulfobulbaceae (3 species, 13 clones), Desulfomicrobiaceae (1 species, 3 clones) and Desulfovibrionaceae (2 species, 3 clones). These results suggested that the intestinal tract of spotnape ponyfish was populated by diverse species of SRB.View full abstractDownload PDF (240K)
Program and Abstracts
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Atsushi Hagiwara2012 Volume 60 Issue 4 Pages 523-588
Published: December 20, 2012
Released on J-STAGE: March 23, 2015
JOURNAL FREE ACCESSDownload PDF (897K)
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