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Volume 70, Issue 1
Displaying 1-10 of 10 articles from this issue
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Originals
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IZUMI SAKURAI, MANABU SHIMONO, SHIGEKI KONNO, KATSUHIKO MIZUNO, MORIYO ...2004 Volume 70 Issue 1 Pages 1-7
Published: 2004
Released on J-STAGE: April 28, 2005
JOURNAL FREE ACCESSThis study examined the effects of current velocity and direction on the growth of the Japanese scallop Patinopecten (Mizuhopecten) yessoensis in hanging culture. Scallops of 1-year-old were suspended from four surfaces of a cubic frame with exhalent margin (posterior) oriented outside, and placed in cultivation areas of Shikabe and Mashike, Hokkaido, Japan, for eight and eleven months, respectively. In Shikabe, the growth of scallops with inhalent margin (anterior) oriented NNW was highest, whereas that of scallops with posterior oriented NNW was significantly lower. The growth of scallops in Mashike with anterior oriented SW and NW was significantly higher. The current component of S-SE and NE-ESE with speed of <10 cm/s was dominant in Shikabe and Mashike, respectively. The results suggested that the presence of dominant current from a specific direction affected the growth of hanging cultured scallop: the feeding was enhanced and inhibited by anterior and posterior oriented dominant currents with speed of <10 cm/s, respectively.View full abstractDownload PDF (514K) -
MASATO ARITAKI, KENGO OHTA, YUUJI HOTTA, MASATOMO TAGAWA, MASARU TANAK ...2004 Volume 70 Issue 1 Pages 8-15
Published: 2004
Released on J-STAGE: April 28, 2005
JOURNAL FREE ACCESSThe occurrence of metamorphosis-related abnormalities under different rearing water temperatures (9-21°C) was examined in hatchery-reared juveniles of spotted halibut Verasper variegatus. The growth and development of the larvae were accelerated at higher temperatures. After completing metamorphosis, juveniles were categorized into three morphological types (normal, pseudoalbino and ambicolored fish) based on eye location and body color (pigmentation). The temperature spectrum of the occurrence of these three morphological types was consistent among three experiments carried out in different years, and the normal fish occurred most frequently at 18°C, pseudoalbino fish at 12°C and ambicolored fish at 21°C. The morphological characteristics of both body sides (left and right) in pseudoalbino and ambicolored fish were similar to the blind side and ocular side, respectively, of normal fish, suggesting the occurrence of abnormal asymmetrical development in either body side.
These results suggest the possible involvement of rearing temperature, possibly through the timing of metamorphosis and/or the speed of larval growth/development, in the asymmetrical differentiation of left and right body sides during metamorphosis.View full abstractDownload PDF (550K) -
HIDEYUKI YAMASHITA2004 Volume 70 Issue 1 Pages 16-21
Published: 2004
Released on J-STAGE: April 28, 2005
JOURNAL FREE ACCESSDaily landing data of Japanese longliners and Chinese vessels for the red tilefish Branchiostegus japonicus from the East China Sea were obtained from April 1996 to March 1999 at the Nagasaki Fish Market. The Total length (TL) of the fish sampled from each category of market size was measured. The Monthly landing amount and the TL composition of the landed fish for each month were estimated. The trend of decline in landings by Japanese longliners was caused by declines in both the stock size and number of fishing boats. The Share of landings by Chinese boats is dominant at Nagasaki Fish Market. The Majority of fish landed by Chinese boats are around 30 cm in TL. Individual fish smaller 30 cm in TL are very cheap. The results of YP/R analysis show that an increase in size at first capture improves the total income as well as stock size, and therefore methods to preserve the small fishes should be examined in the future.View full abstractDownload PDF (503K) -
KATSUYUKI HAMASAKI, HIROYUKI TAKEUCHI, SATOSHI SHIOZAWA, KAZUHISA TERU ...Article type: Others
Subject area: Others
2004 Volume 70 Issue 1 Pages 22-30
Published: 2004
Released on J-STAGE: April 28, 2005
JOURNAL FREE ACCESSRetention rate, feeding condition and predation of hatchery-reared juveniles of the coral trout Plectropomus leopardus released on a coral reef in Urasoko Bay, Ishigaki Island were investigated to evaluate the effectiveness of acclimation of juveniles to the natural environment before release. Two experiments were conducted and 2000 juveniles [mean total length (TL), 137 mm] and 900 juveniles (mean TL, 79 mm) were stocked in a net cage (400 m2) which was set on the release site in the first and second trials, respectively. After acclimation for 7 days in the net cage, acclimated juveniles (test group) were released with the control groups of 2000 juveniles (mean TL, 142 mm) in the first trial and 900 juveniles (mean TL, 86 mm) in the second trial. Test and control groups were distinguished by different color tags. The second release experiment could not be conducted satisfactorily due to a typhoon. Judging from the feeding incidence, changes of condition factor and visceral weight index of juveniles after release in the first trial, it was considered that juveniles of the test group were more acclimated to the natural environment than those of the control group. Furthermore, juveniles of the test group tended to be less vulnerable to predation by piscivorous animals than those of the control group due to the improvement of behavior of lurking in the coral rubble.View full abstractDownload PDF (432K) -
TETSUYA NISHIKAWA, YUTAKA HORI2004 Volume 70 Issue 1 Pages 31-38
Published: 2004
Released on J-STAGE: April 28, 2005
JOURNAL FREE ACCESSIn order to elucidate the mechanism of bleaching of seaweed Phrphyra by Eucampia zodiacus blooming, we examined the effects of nitrogen, phosphorus and silicon on its growth in culture. The maximum specific growth rate (μm) was 2.4-2.6 d-1 at 20°C and 1.0-1.3 d-1 at 9°C nutrient saturated conditions respectively. The half-saturation constant for growth (Ks) of nitrate, phosphate and silicate were 0.86 and 0.76 μM-N, 0.31 and 0.29 μM-P, 0.88 and 0.91 μM-Si at 20 and 9°C respectively. The minimum cell quota of N, P and Si were calculated 1.0, 1.6 pmol-N/cell, 0.16, 0.24 pmol-P/cell and 2.6, 3.8 pmol-Si/cell at 20 and 9°C respectively.
E. zodiacus was able to grow using nitrate, nitrite, ammonium and glutamine were found to be good nitrogen soures but uric acid, urea and other amino acids were not so well utilized or none. E. zodiacus was capable of using a wide variety of inorganic and organic phosphorus compounds of different molecular structure successfully as a sole P source.
These results suggest that E. zodiacus poses serious damage on “Nori” cultivaiton compared to other species which caused bleaching of seaweed.View full abstractDownload PDF (420K) -
KAZUO IMURA, TETSUYA TAKATSU, NOBUAKI NANJO, OSAMU KIMURA, TOYOMI TAKA ...2004 Volume 70 Issue 1 Pages 39-47
Published: 2004
Released on J-STAGE: April 28, 2005
JOURNAL FREE ACCESSThe spatial distribution of brown sole Pseudopleuronectes herzensteini eggs and larvae, and their food organisms were examined to elucidate the early life history of this species in Mutsu Bay. In April 1990-1997, pelagic larvae were widely distributed in the bay. Vertical distributions of eggs and larvae were investigated at two sampling stations in the bay from late February to late June in 1999-2001. Eggs of early, middle, and late stages occurred mainly in 30-40, 10-20, and 1-20 m layers, respectively. Yolk-sac larvae (stages A-B) occurred chiefly in the 20-40 m layer. The layer of abundant preflexion larvae (stages C-D) was slightly deeper (mainly 20 m depth) than that of copepod nauplii (10-20 m layer) as larval initial food. Larval concentration at 20 m depth may play some role in avoiding transportation to a shallow area unsuitable for settlement. Because the weighted-mean-depths of relatively larger larvae (flexion or postflexion larvae, stages E-G) were deeper (≥24 m) than those of stages C-D larvae (20-22 m), larvae would ontogenetically migrate for settlement.View full abstractDownload PDF (503K) -
AKIMASA HABANO, KAZUHIKO ANRAKU, TATSURO MATSUOKA, MASATAKA HIGASHI, H ...2004 Volume 70 Issue 1 Pages 48-53
Published: 2004
Released on J-STAGE: April 28, 2005
JOURNAL FREE ACCESSSinking motions of tuna longlines at the surface layer, 0-30 m depth, were studied at sea by using depth loggers attached to the bases (main lines) and tips (hooks) of branch lines. Characteristic sinking patterns and changes in sinking velocity were compared between main lines and hooks. Initially, main lines and hooks sank at different velocities; the main lines sank at 7.7 ± 1.5 cm/s and hooks at 18.7 ± 3.6 cm/s. There was no significant relationship between the velocities and the duration of the initial sinking. Deceleration for hooks started 36 to 112 s after shooting. Consequently, their sinking velocities became identical to those of the main lines. The sequence of sinking motions of a main line and a hook can be modeled as three stages: independent free fall at their own velocities where a hook sinks faster (initial motion), deceleration of a hook after the branch line is stretched (transitional motion) and simultaneous sinking of a main line and a hook which is suspended from the main line (final motion). The above model suggests that casting of stretched branch lines results in a prolonged sinking time to the critical depth for a hook.View full abstractDownload PDF (359K) -
HIDEKI KISHIMURA, KENJI HAYASHIArticle type: Others
Subject area: Others
2004 Volume 70 Issue 1 Pages 54-59
Published: 2004
Released on J-STAGE: April 28, 2005
JOURNAL FREE ACCESSPhospholipase A2 isozyme (PLA2 II), which showed different mobility on native PAGE from that of the PLA2 (PLA2 I) purified previously, was isolated from the pyloric ceca of the starfish Asterina pectinifera. The PLA2 II was mainly oleic acid released from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. The N-terminal amino acid sequence of the PLA2 II was SVYQF. For hydrolysis of egg yolk phosphatidylcholine, the optimum pH and temperature of the PLA2 II were at around pH 9.0 and 50°C, respectively, and the activity was enhanced by 1 mM or higher concentration of Ca2+. The PLA2 II as well as porcine pancreatic PLA2 did not show fatty acid specificity for hydrolysis of phosphatidylcholine from squid mantle muscle. The PLA2 II from the pyloric ceca of A. pectinifera, however, hydrolyzed phosphatidylcholine more effectively than phosphatidylethanolamine unlike porcine pancreatic PLA2. These characteristics of the PLA2 II were the same as those of the PLA2 I.View full abstractDownload PDF (355K) -
HISAE KASAI, EMI SUGIYAMA, MAMORU YOSHIMIZUArticle type: Others
Subject area: Others
2004 Volume 70 Issue 1 Pages 60-65
Published: 2004
Released on J-STAGE: April 28, 2005
JOURNAL FREE ACCESSTo control hygienic conditions at fishing ports, qualitative and quantitative bacterial observations have to be considered. In the fishing port located at Shibetsu town, Hokkaido, where the hazard analysis and critical control point (HACCP) system is performed, the distribution and composition of heterotrophic bacterial flora and coliform bacteria were studied in this hygienically controlled site. There was a little difference in the quality of water collected from inside and outside of the harbor. The number of viable bacteria in the surface seawater varied seasonally from 102 to 104 CFU/mL. The generic composition of bacteria collected from back part of the harbor, entrance of the harbor, and the front of the fish market was compared. The generic composition of the bacterial flora included the genera Pseudomonas, Alteromonas and Vibrio, which were observed through the year. Moraxella and gram-positive bacteria were also isolated in front of the fish market. Coliform were isolated inside and outside of the harbor throughout the year, and their counts increased as water temperature increased.View full abstractDownload PDF (564K)
Short paper
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NORIMASA WATANABE, ATSUSHI FUKUI, NOBUHIRO SUZUKI, ITSURO UOTANIArticle type: Others
Subject area: Others
2004 Volume 70 Issue 1 Pages 66-68
Published: 2004
Released on J-STAGE: April 28, 2005
JOURNAL FREE ACCESS
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